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Soil biodiversity for agricultural sustainability
Abstract
We critically highlight some evidence for the importance of soil biodiversity to sustaining (agro-)ecosystem functioning and explore directions for future research. We first deal with resistance and resilience against abiotic disturbance and stress. There is evidence that soil biodiversity does confer stability to stress and disturbance, but the mechanism is not yet fully understood. It appears to depend on the kind of stress and disturbance and on the combination of stress and disturbance effects. Alternatively, community structure may play a role. Both possible explanations will guide further research. We then discuss biotic stress. There is evidence that soil microbial diversity confers protection against soil-borne disease, but crop and soil type and management also play a role. Their relative importance as well as the role of biodiversity in multitrophic interactions warrant further study. Henceforth, we focus on the effects of plant and soil biodiversity on nutrient and water use efficiencies as important ecological functions in agroecosystems. The available evidence suggests that mycorrhizal diversity positively contributes to nutrient and, possibly, water use efficiency. Soil fauna effects on nutrient and water use efficiencies are also apparent, but diversity effects may be indirect, through effects on soil structure. We present a conceptual diagram relating plant and soil biodiversity with soil structure and water and nutrient use efficiencies as a framework for future studies. We then consider how cropping systems design and management are interrelated and how management options might be interfaced with farmers’ knowledge in taking management decisions. Finally, we attempt to express some economic benefits of soil biodiversity to society as part of a wider strategy of conserving and using agrobiodiversity.
... The goals of organic farming are sustainable soil use and improved soil quality through, for example, enhancing soil organic matter content, supporting soil biota and closing nutrient cycles . Agroecosystem stability increases with the increasing capacity of the soil to function as well as with sustainable resource use (Brussaard et al., 2007). Organic farming aims to maintain long-term productivity under present and future challenges such as climate change-related shifts in precipitation patterns and rising temperatures (Begum et al., 2022). ...
... Successful and sustainable farm management depends on the holistic integration of different agricultural strategies, where the highest level of management regarding the system scale with associated spatial and temporal interventions is the choice of the farming type, e.g., mixed farming, and the cropping system, followed by lower level management decisions, such as organic matter management and tillage (Brussaard et al., 2007). In Europe, a decoupling of livestock and cropping systems took place in conventional farming as part of the agricultural industrialization (Ryschawy et al., 2013) with stockless farming relying on nutrient inputs from mineral fertilizers. ...
... Deep inversion ploughing was the dominant soil preparation technique in both conventional and organic agriculture, but less destructive methods are gaining attention, e.g., limiting soil disturbance by reducing ploughing depth or avoiding soil inversion is widely studied and evaluated in response to a diverse set of agronomic and environmental objectives (Cooper et al., 2016). These are, for example, enhancing soil biodiversity (Brussaard et al., 2007), microbial biomass and activity, and earthworm abundance (Kuntz et al., 2013), preventing fast mineralisation, thus reducing nutrient losses through leaching (Frick et al., 2022), and maintaining or even increasing soil carbon stocks (Cooper et al., 2016;Krauss et al., 2022). Studies on conventional agriculture also describe reduced energy use (Kusek et al., 2016), and maintenance or increase of yield and yield stability (Xu et al., 2019). ...
Context: High productivity and yield stability over time in combination with a reduction in the crop failure risk are the principal goals of both conventional and organic agriculture. These goals are achieved in organic agriculture through the maintenance of soil fertility and soil functions through agronomic practices such as balanced crop rotations and the application of organic amendments. Reduced tillage constitutes an important practice that limits the disturbance to the soil structure and biota, but deep ploughing is frequently used in organic farming for weed control and aeration of heavy soils. Objective: This study aimed to assess the impact of mixed organic farms and farms without livestock, so called stockless farms, with their respective crop rotations and fertilization management, and the effect of reduced tillage on yield dynamics. Methods: We compared yield dynamics i.e., crop yield, yield stability and the production risk, of three organic farming systems involving four levels of tillage intensity each at the Organic Arable Farming Experiment Gladbacherhof (OAFEG), Germany, based on a long-term (24 year) dataset. The six-year crop-rotation of a mixed farm was compared to stockless farming with rotational alfalfa ley and stockless farming with cash crops. The levels of tillage intensity ranged from deep inversion ploughing to non-inversion tillage. The yield data from the OAFEG trial were evaluated with respect to the mean yield data from all cropland systems at Gladbacherhof research farm. We calculated the yield dynamics of the complete crop rotation as well as three crops within the rotations i.e., winter wheat, winter rye and potato. Results: The most promising combination of high yield and yield stability was mixed farming with deep (30 cm) and shallow (15 cm) ploughing, in contrast to stockless farming (with ley) with non-inversion tillage. Similar results were recorded for cereals, but not for potatoes. Stockless farming with cash crops and non-inversion tillage had the highest production risk, i.e., the highest probability of falling below the defined critical yield level. Conclusions: Under the predominant heavy soil conditions in central Germany, non-inversion tillage can't keep up with inversion tillage regarding a stable organic production. Mixed farming with livestock which is representative of traditional organic farming system was found to produce high yields, but also stockless farming with rotational alfalfa ley was competitive. Implications: Stockless or "vegan" organic farming can be an alternative production system to organic mixed farming with stable yields provided that rotational alfalfa ley is part of the crop rotation. Ploughing depth can be reduced without affecting productivity.
... While assessing all this information is essential for crop system functionality, to our knowledge, many studies overlook crucial elements in assessing the by-side effects of nematicides, such as their impact on the abundance, structure, composition, and interaction network of free-living nematodes. Such considerations hold substantial importance, particularly given the multi-scale nature of biodiversity, which necessitates minimizing disturbances to effectively uphold its ecological functions [18]. Hence, it is necessary to conduct further investigations to address existing gaps on the side effects associated with chemical treatments on non-target nematodes, which are equally affected due to their biological similarity, thus presenting an essential matter given their contribution to soil productivity [19]. ...
... (3) application of Furfural at a rate of 3 mL per plant or 31 µL per 100 g of soil (purchased from Sigma-Aldrich); and (4) application of M. azedarach water extract (MWE) at a rate of 430 mL per plant or 1.15 g of dry extract per 100 g of soil. The chosen concentrations for these treatments slightly exceeded the EC 50 values determined in a prior pot trial for MWE and Furfural [18]. The application volume for all treatments was 500 mL, distributed in a circular area with a 26-cm diameter around the base of each plant. ...
... This positive and promising outcome suggests that MWE not only acts as a nematicide but also as a soil improver, as its application promotes the proliferation of beneficial nematode populations over the long term. M. azedarach botanical products contain a combination of easily and slowly degradable compounds, such as cellulose, hemicellulose, and lignin [42], which can serve as food sources for the microbial community [20,43], thereby increasing the abundance of microbial-feeding nematodes [18]. The sustained increase in free-living nematodes indicated that the labile organic matter introduced by MWE remained available for decomposition. ...
In a greenhouse experiment, we studied the impact of Melia azedarach ripe fruit water extract (MWE), Furfural (a key ingredient of M. azedarach), and the commercial nematicide Oxamyl (Vydate ® 10 SL) on the soil free-living nematode community. Treatments were applied every 20 days for two months, and soil samples were collected 3 days after the last application (3DAA) and at the end of the cultivation period (34DAA). We assessed short-and long-term effects on nematode community structure, metabolic footprint, genus composition, and interaction networks. Oxamyl and Furfural significantly reduced bacterial and fungal feeder populations. MWE had no impact on free-living nematode populations. Oxamyl and Furfural-treated soil samples were dominated by Rhabditis at 3DAA and Meloidogyne spp. at 34DAA. On the contrary, MWE-treated soil showed a balanced distribution, with Rhabditis, Panagrolaimus, Mesorhabditis, and Diploscapter being equally abundant. MWE treatment exhibited higher diversity indices (Shannon and Simpson) and equitability. Network analysis showed that the Oxamyl network had the highest fragmentation, while the MWE and Furfural networks had higher cohesion compared to the control. Mesorhabditis spp. in the MWE network played a crucial role, being directly connected to the omnivore genera Thonus and Aporce-laimellus. Our results indicated that continuous MWE application, besides controlling Meloidogyne spp., could enhance the structure and stability of the soil-free-living nematode community.
... While assessing all this information is essential for crop system functionality, to our knowledge, many studies overlook crucial elements in assessing the by-side effects of nematicides, such as their impact on the abundance, structure, composition, and interaction network of free-living nematodes. Such considerations hold substantial importance, particularly given the multi-scale nature of biodiversity, which necessitates minimizing disturbances to effectively uphold its ecological functions [18]. Hence, it is necessary to conduct further investigations to address existing gaps on the side effects associated with chemical treatments on non-target nematodes, which are equally affected due to their biological similarity, thus presenting an essential matter given their contribution to soil productivity [19]. ...
... (3) application of Furfural at a rate of 3 mL per plant or 31 µL per 100 g of soil (purchased from Sigma-Aldrich); and (4) application of M. azedarach water extract (MWE) at a rate of 430 mL per plant or 1.15 g of dry extract per 100 g of soil. The chosen concentrations for these treatments slightly exceeded the EC 50 values determined in a prior pot trial for MWE and Furfural [18]. The application volume for all treatments was 500 mL, distributed in a circular area with a 26-cm diameter around the base of each plant. ...
... This positive and promising outcome suggests that MWE not only acts as a nematicide but also as a soil improver, as its application promotes the proliferation of beneficial nematode populations over the long term. M. azedarach botanical products contain a combination of easily and slowly degradable compounds, such as cellulose, hemicellulose, and lignin [42], which can serve as food sources for the microbial community [20,43], thereby increasing the abundance of microbial-feeding nematodes [18]. The sustained increase in free-living nematodes indicated that the labile organic matter introduced by MWE remained available for decomposition. ...
In a greenhouse experiment, we studied the impact of Melia azedarach ripe fruit water extract (MWE), Furfural (a key ingredient of M. azedarach), and the commercial nematicide Oxamyl (Vydate ® 10 SL) on the soil free-living nematode community. Treatments were applied every 20 days for two months, and soil samples were collected 3 days after the last application (3DAA) and at the end of the cultivation period (34DAA). We assessed short-and long-term effects on nematode community structure, metabolic footprint, genus composition, and interaction networks. Oxamyl and Furfural significantly reduced bacterial and fungal feeder populations. MWE had no impact on free-living nematode populations. Oxamyl and Furfural-treated soil samples were dominated by Rhabditis at 3DAA and Meloidogyne spp. at 34DAA. On the contrary, MWE-treated soil showed a balanced distribution, with Rhabditis, Panagrolaimus, Mesorhabditis, and Diploscapter being equally abundant. MWE treatment exhibited higher diversity indices (Shannon and Simpson) and equitability. Network analysis showed that the Oxamyl network had the highest fragmentation, while the MWE and Furfural networks had higher cohesion compared to the control. Mesorhabditis spp. in the MWE network played a crucial role, being directly connected to the omnivore genera Thonus and Aporce-laimellus. Our results indicated that continuous MWE application, besides controlling Meloidogyne spp., could enhance the structure and stability of the soil-free-living nematode community.
... While assessing all this information is essential for crop system functionality, to our knowledge, many studies overlook crucial elements in assessing the by-side effects of nematicides, such as their impact on the abundance, structure, composition, and interaction network of free-living nematodes. Such considerations hold substantial importance, particularly given the multi-scale nature of biodiversity, which necessitates minimizing disturbances to effectively uphold its ecological functions [18]. Hence, it is necessary to conduct further investigations to address existing gaps on the side effects associated with chemical treatments on non-target nematodes, which are equally affected due to their biological similarity, thus presenting an essential matter given their contribution to soil productivity [19]. ...
... (3) application of Furfural at a rate of 3 mL per plant or 31 µL per 100 g of soil (purchased from Sigma-Aldrich); and (4) application of M. azedarach water extract (MWE) at a rate of 430 mL per plant or 1.15 g of dry extract per 100 g of soil. The chosen concentrations for these treatments slightly exceeded the EC 50 values determined in a prior pot trial for MWE and Furfural [18]. The application volume for all treatments was 500 mL, distributed in a circular area with a 26-cm diameter around the base of each plant. ...
... This positive and promising outcome suggests that MWE not only acts as a nematicide but also as a soil improver, as its application promotes the proliferation of beneficial nematode populations over the long term. M. azedarach botanical products contain a combination of easily and slowly degradable compounds, such as cellulose, hemicellulose, and lignin [42], which can serve as food sources for the microbial community [20,43], thereby increasing the abundance of microbial-feeding nematodes [18]. The sustained increase in free-living nematodes indicated that the labile organic matter introduced by MWE remained available for decomposition. ...
In a greenhouse experiment, we studied the impact of Melia azedarach ripe fruit water extract (MWE), Furfural (a key ingredient of M. azedarach), and the commercial nematicide Oxamyl (Vydate® 10 SL) on the soil free-living nematode community. Treatments were applied every 20 days for two months, and soil samples were collected 3 days after the last application (3DAA) and at the end of the cultivation period (34DAA). We assessed short- and long-term effects on nematode community structure, metabolic footprint, genus composition, and interaction networks. Oxamyl and Furfural significantly reduced bacterial and fungal feeder populations. MWE had no impact on free-living nematode populations. Oxamyl and Furfural-treated soil samples were dominated by Rhabditis at 3DAA and Meloidogyne spp. at 34DAA. On the contrary, MWE-treated soil showed a balanced distribution, with Rhabditis, Panagrolaimus, Mesorhabditis, and Diploscapter being equally abundant. MWE treatment exhibited higher diversity indices (Shannon and Simpson) and equitability. Network analysis showed that the Oxamyl network had the highest fragmentation, while the MWE and Furfural networks had higher cohesion compared to the control. Mesorhabditis spp. in the MWE network played a crucial role, being directly connected to the omnivore genera Thonus and Aporcelaimellus. Our results indicated that continuous MWE application, besides controlling Meloidogyne spp., could enhance the structure and stability of the soil-free-living nematode community.
... Soil biological indicators are crucial for soil quality. This is becoming increasingly important in today's farming, which is moving towards sustainability, cost reduction, and soil conservation [26]. Soil fauna helps plants obtain nutrients, improve soil structure, and regulate soil water levels [27]. ...
Soil tillage intensity influences the distribution of nutrients, and soil’s physical and me-chanical properties, as well as gas flows. The impact of reduced tillage on these indices in spring barley cultivation is still insufficient and requires more analysis on a global scale. This study was carried out at Vytautas Magnus University, Agriculture Academy (Lithu-ania) in 2022–2023. The aim of the investigation was to determine the effect of the tillage systems on the soil temperature, moisture content, CO2 respiration and concentration in spring barley cultivation limited by the semi-humid subarctic climate. Based on a long-term tillage experiment, five tillage systems were tested: deep and shallow mold-board ploughing, deep cultivation-chiselling, shallow cultivation-chiselling, and no-tillage. Shallow ploughing technology was found to be better at conserving soil moisture and maintaining a higher temperature. Deep cultivation had a lower moisture content and lower soil temperature. Shallow cultivation fields in most cases increased CO2 emissions and CO2 concentration. The results show that in direct sowing fields, most cases had a positive effect on crop density. Direct sowing fields resulted in significantly lower grain yields of spring barley in the years studied.
... Au-delà des impacts des mélanges biochar-compost sur les propriétés physico-chimiques du sol et la productivité des cultures, il est également important de caractériser l'influence de ces amendements sur la composante biologique du sol. Il est en effet aujourd'hui largement reconnu que le fonctionnement d'un agrosystème et sa capacité à délivrer des services écosystémiques dépend des organismes qu'il abrite et de leur activité (Briones, 2018;Brussaard et al., 2007). Afin de préciser notre compréhension de l'impact des mélanges biochar-compost sur le fonctionnement des agrosystèmes, nous avons suivi sur le site de Beauvais (Oise) l'évolution des communautés de vers de terre et des paramètres microbiologiques du sol pendant trois années culturales. ...
L'optimisation du fonctionnement des agroécosystèmes représente un défi majeur à l'heure où la pression croissante sur les ressources naturelles et la nécessité de répondre aux besoins alimentaires mondiaux imposent une gestion plus efficiente et durable des terres agricoles. Dans ce contexte, l’un des objectifs de la transition agroécologique est de favoriser le bouclage des grands cycles en promouvant l’augmentation de la biodiversité et la substitution des intrants minéraux par des matières fertilisantes issues de ressources renouvelables. Cependant, compte tenu de la multiplicité des interactions biotiques et abiotiques opérant au sein du système sol-plante, l’acquisition de nouvelles connaissances sur les régulations biologiques et physico-chimiques des cycles biogéochimiques est requise afin d’être en mesure de quantifier et de prédire les intérêts et les limites des pratiques et techniques de culture innovantes et de mettre en place une gestion avisée des ressources pédologiques.
Dans ce mémoire, je m’attèle dans un premier temps à décrire l’évolution de mes réflexions sur la prise en compte des processus opérant au sein du système sol-plante en vue de concevoir des agroécosystèmes multifonctionnels et durables. Plus spécifiquement, je fais état de mes principales recherches sur la compréhension des processus rhizosphériques impliqués dans la mobilisation du phosphore et de leurs implications pour l’amélioration de la disponibilité du phosphore dans les sols. Puis, j’aborde la question de l’utilisation de co-produits industriels ou agricoles comme amendements multifonctionnels pour les sols. J’illustre ma démarche en accordant un intérêt particulier au biochar, objet de mes recherches depuis ma thèse jusqu’à aujourd’hui, et à ses effets sur le fonctionnement du système sol-plante.
Dans un second temps, je propose un projet de recherche basé sur une amélioration de la compréhension des processus biogéochimiques opérant au sein du système sol-plante à travers une approche holistique gravitant autour de trois piliers de l’agroécologie et de l’agriculture de conservation, à savoir le recyclage des nutriments au moyen d’amendements organiques, la réduction du travail du sol et l’implantation d’un couvert, en particulier diversifié en espèces. La démarche proposée dans ce projet se veut de complexité croissante : elle propose d’étudier les interactions sol-plante et leurs conséquences sur le fonctionnement du sol en réponse à l’apport d’amendements, puis aborde la question du travail du sol et de la stratification de la disponibilité en nutriments sur ces interactions et se clôture par l’intégration de la complexité de ces interactions dans les systèmes diversifiés en espèces végétales. Un exemple de perspectives à ces études termine ce projet en soulignant la nécessité d’étudier le couplage des cycles biogéochimiques à travers leurs liens directs et indirects afin de maximiser la fourniture de service écosystémiques par les sols et les agroécosystèmes.
... Due to the interaction between bacteria and roots in the rhizospheric soil and their important role in nutrient conversion, bacteria and roots play the most important role in determining the rhizospheric vector angle (Ren et al. 2020). The abundance of actinomycetes, however, became the main factor in the vector analysis of non-rhizospheric soil, perhaps because some actinomycetes can provide nutrients and improve soil structure (Brussaard et al. 2007). The P limitation did not differ significantly between the rhizospheric and bulk soils at the moderate rate of organic manure application, indicating that this rate could alleviate P limitation in both soils in a balanced manner. ...
... For such an agroecological transition, numerous practices that optimize aboveground functional biodiversity are proposed while relatively little attention has been given to practices that drive the intensification of belowground biodiversity and processes. However, soil organisms interact in intricate networks to deliver key functions at the basis of ecosystem services: (i) soil organic matter dynamics, (ii) nutrient cycling, (iii) maintenance of soil structure, and (iv) pest regulation (Brussaard et al., 2007;Kibblewhite et al., 2008). Plant functions are directly or indirectly affected by these soil ecological processes (De Deyn et al., 2004). ...
... Owing to their ability to respond sensitively to environmental changes, soil microorganisms that play significant roles in many processes of soil ecosystems are used as ideal biological indicators of soil health and quality (Brussaard et al., 2007). Studies have shown that long-term continuous cropping can affect soil microbial community structure and diversity, for example, long-term continuous cropping can reduce the size of beneficial soil microbial communities and increase the size of harmful microbial communities (Wu et al., 2007;Caporaso et al., 2012;She et al., 2017). ...
Introduction
Continuous strawberry cropping often causes soil-borne diseases, with 20 calcium cyanamide being an effective soil fumigant, pig manure can often be used as soil organic fertilizer. Its impact on soil microorganisms structure, however, remains unclear.
Methods
This study investigated the effectiveness of calcium cyanamide and pig manure in treating strawberry soil, specifically against strawberry anthracnose. We examined the physical and chemical properties of the soil and the rhizosphere microbiome and performed a network analysis.
Results
Results showed that calcium cyanamide treatment significantly reduces the mortality rate of strawberry in seedling stage by reducing pathogen abundance, while increasing actinomycetes and Alphaproteobacteria during the harvest period. This treatment also enhanced bacterial network connectivity, measured by the average connectivity of each Operational Taxonomic Unit (OTU), surpassing other treatments. Moreover, calcium cyanamide notably raised the levels of organic matter, available potassium, and phosphorus in the soil–key factors for strawberry disease resistance and yield.
Discussion
Overall, applying calcium cyanamide to soil used for continuous strawberry cultivation can effectively decrease anthracnose incidence. It may be by changing soil physical and chemical properties and enhancing bacterial network stability, thereby reducing the copy of anthracnose. This study highlights the dual benefit of calcium cyanamide in both disease control and soil nutrient enhancement, suggesting its potential as a valuable tool in sustainable strawberry farming.
... Biodiversity, above and belowground, is vital for ecosystem functioning (Brussaard et al., 2007;Bardgett and Van Der Putten, 2014). Concurrently, agricultural diversification has been shown to have predominantly positive effects on biodiversity and to enhance multiple ecosystem services (Tamburini et al., 2020). ...
Simple rotation systems as wheat (Triticum aestivum L.)-fallow practiced in semi-arid regions are currently being transformed by replacing fallow with winter pea (Pisum sativum L.). However, there is insufficient understanding of how such diversification of plant functional groups impacts the biological and chemical soil properties which drive ecosystem services. This study investigated how diversifying rotation system coupled with nitrogen (N) fertilization impacts the diversity and activity of microbial communities and other essential soil properties such as soil organic carbon (C). Soils from a long-term field experiment (Pendleton, OR, USA) were sampled in 2021 at two depths (0-5 cm and 5-10 cm) and characterized for microbial biomass carbon (MBC), prokaryote community composition and diversity (16 S amplicon sequencing), activities of enzymes involved in C, N, phosphorous (P) and sulfur (S) cycles and soil chemical properties. The results indicated that MBC and enzyme activity were greater in the wheat-pea rotation compared to wheat-fallow, while fertilization was not a significant factor for these properties. Enzyme activities normalized by MBC showed fewer differences suggesting that the impact is mostly due to differences in MBC. Replacing fallow with pea decreased alpha diversity metrics at both depths and for both the highest and the lowest level of taxonomic hierarchy, although the effects upon phyla richness were not statistically significant. Nitrogen fertilizer decreased the Shannon index and Shannon evenness, especially in the 5-10 cm depth. While communities at the amplicon sequence variant (ASV) level were clearly separated by the rotation system, they were less separated by fertilization which distinguished communities only in the wheat-fallow system. Redundancy analysis (RDA) followed by variance partitioning analysis (VPA) indicated that soil properties explained most of the variation in the community structure at the phylum level with rotation and fertilization having no unique contribution. This suggests that the effects of rotation and fertilization are mediated through the changes these practices induce upon other soil properties. Overall, the results show that changing wheat-fallow into wheat-pea cover crop systems increases some soil health indicators while decreasing diversity which suggests that no direct coupling exists between above and belowground biodiversity.
... En este sentido, los parámetros relativos a la comunidad microbiana edáfica son muy sensibles a los cambios en la calidad y sostenibilidad del suelo por acciones antrópicas [5,6]. Además, los estudios centrados en la comunidad microbiana del suelo son cruciales puesto que los microorganismos son en gran parte responsables de muchas de las funciones del suelo, entre las que destaca la producción de alimentos, el ciclo de los elementos, la depuración de contaminantes, etc. [7]. ...
... The Simpson index of all treatments was higher than that of the CK, indicating that microbial agents significantly improved the abundance and diversity of microorganisms in soil (Table 2). Although it is not always beneficial to increase the microbial community in a soil infected with pathogens, the majority believed that soils with higher species diversity not only improve disease resistance but also increase productivity [45][46][47][48][49][50]. Based on this, different biocontrol bacteria were combined to achieve complementary advantages and enhance the biological control characteristics of pathogenic bacteria. ...
The application of beneficial microbial consortium can effectively improve plant disease resistance and its growth. Various fungi were compounded with Bacillus velezensis LJ02 and applied to watermelon plants in this paper. The results showed that the microbial consortium T2 (compounded Bacillus velezensis LJ02 with Aspergillus aculeatus 9) can effectively control gummy stem blight and powdery mildew in watermelon, while the control effect reached 83.56% and 70.93%, respectively (p < 0.05). Compound treatment improved the diversity and richness of the rhizosphere microbial community structure, and the relative abundance of Caulobacterales and Xanthomonadaceae significantly increased after applying T2 to the soil. Meanwhile, the internode length was significantly decreased 28% (p < 0.05), and the maximum leaf length increased 10.33% (p < 0.05). In addition, the microbial consortium delays the maturity of watermelon vegetables. By studying the effects of microbial consortium on watermelon seedlings, our study provides a theoretical basis for the popularization and application of the compound inoculant.
... Eukaryotic microorganisms include most of the natural microbes and are associated with the sustainability of the soil-based ecosystem and biological processes (Crossley and Hendrix 2004;Falkowski et al. 2008;DeLong 2009;Aslani et al. 2022). The soil eukaryotic microbiome plays a role in soil structure formation, litter decomposition, and nutrient cycling (Brussaard et al. 2007;Zhao et al. 2018;TiÁskal et al. 2021). In addition, eukaryotes play a key role in soil fertility and influence prokaryotic community structure (Ali et al. 2018). ...
The date palm (Phoenix dactylifera) is an important cultivated crop in arid areas. Here, we studied the effect of plant genotype and type of fertilizers on the eukaryotic community structures of the date palm rhizosphere. Samples were collected from one wild population, five cultivars from two farms, and a factorial fertilizer experiment (organic, chemical, and biofertilizer) in Qatar. The eukaryotic communities were sequenced using a next-generation sequencing method. A total of 2422 Operational Taxonomic Units (OTUs) were identified as belonging to 15 phyla, Chlorophyta, Streptophyta, Imbricatea, Chytridiomycota, Ascomycota, Olpidiomycota, being dominant. The wild-type date palms showed a low number of OTUs compared to cultivated date palms, potentially due to the strong influence of soil salinity and low moisture level. However, the wild-type date palm hosted the highest number of unique OTUs. PCA revealed that the eukaryotic microbiome of the wild date palms was separated from the cultivated date palms and that the eukaryotic microbial diversity varied between date palm cultivars in similar environments. Using the highest amounts of biofertilizer and chemical fertilizer decreased the species diversity within the samples. However, a high concentration of biofertilizer combined with a low concentration of chemical fertilizers enhanced the eukaryotic diversity within the samples. We conclude that cultivar type (biotic factor), type of fertilizer, and dosage (abiotic factor) play significant roles in determining the microbiome diversity of the rhizosphere. The wild date palm population could potentially host salt and drought-tolerating eukaryotes that should be further investigated for future development of biofertilizers suitable for drylands.
... Biological activity is essential for biogeochemical cycles, residue degradation and, of course, for biodiversity, all of which is important to sustain agro-ecosystems functioning [102]. Soil microbial populations play a key role in nitrogen fixation, in the decomposition of organic substances and in nutrient cycling. ...
Agricultural residues are produced in large quantities and their management is an issue all over the world. Many of these residues consist of plant materials in different degrees of transformation, so returning them back to soil is a management option that closes loops in a circular economy context. The objective of this paper is to summarize current knowledge on the options and effects of reusing agricultural residues as organic soil amendments. The reuse of these residues in soil is a good solution for minimizing the problems associated with their management, while improving soil health and ecosystem functions. While some agricultural residues can be applied directly to soil, others will need previous transformations such as composting to improve their properties. This allows the recovery of plant nutrients and increase in soil organic matter contents, with many positive effects on the soil’s physical, chemical and biological properties, and ultimately, crop production, although potential risks derived from some materials must also be considered. The concept of regenerative agriculture and soil management using organic soil amendments contribute to the significant enhancement of soil biodiversity, the protection of the environment and climate goal achievement.
... Почвенная микробиота, представленная бактериями и грибами, играет чрезвычайно важную роль в круговороте питательных веществ и жизненно важных элементов, оказывает прямое и косвенное влияние на растения, продуктивность почв [1,2]. Бактерии и грибы вносят значительный вклад в эффективность использования воды и питательных веществ, что в конечном итоге отражается на продуктивности растений [3]. При этом изменение биоразнообразия микроорганизмов может служить индикатором нарушений в землепользовании. ...
The yield of potatoes and other crops is influenced by many factors, one of the most important is the complex condition of the soil. Soil research more often focuses on the determination of its physical and chemical properties, but rarely takes into account the bacterial community and its diversity. In this work, the bacterial microbiota of soils cultivated with potato was evaluated. Using metabarcoding and full-fragment sequencing of the 16S rRNA site, by nanopore sequencing, primary screening of the bacterial community of fields in three administrative districts of the Sverdlovsk region: the city of Yekaterinburg, Beloyarsky and Sysertsky districts was carried out in 2022. As a result, 2371 operational taxonomic units (OTUs) were identified to the species level. More than half of the relative bacterial abundance is occupied by the phylum Proteobacteria. Three orders represent more than one-third of the total bacterial community: Burkholderiales, Hyphomicrobiales, and Acidobacteriales. The most common bacterial genera in cultivated agricultural soils of the Sverdlovsk region are Bradyrhizobium, Massilia, Gaiella, Sphingomonas, Lysobacter and Gemmatimonas. The obtained results of alpha- and beta-diversity analysis allow us to conclude that, despite the statistically significant difference in the number of detected OTUs between some fields, there is no difference in their diversity by study objects in the administrative districts of the Sverdlovsk region.
... Microbes present in the soil are involved in the nutrient cycling, soil structure formation, and response to abiotic and biotic stress (Mayak et al., 2004;Brussaard et al., 2007). Plant growth has also been reported to be regulated by the interactions between plants and soil microbiome (Sasse et al., 2018). ...
Tetrastigma hemsleyanum Diels et Gilg, commonly known as Sanyeqing (SYQ), is an important traditional Chinese medicine. The content of bioactive constituents varies in different cultivars of SYQ. In the plant growth related researches, rhizosphere microbiome has gained significant attention. However, the role of bacterial communities in the accumulation of metabolites in plants have not been investigated. Herein, the composition of bacterial communities in the rhizosphere soils and the metabolites profile of different SYQ cultivars’ roots were analyzed. It was found that the composition of microbial communities varied in the rhizosphere soils of different SYQ cultivars. The high abundance of Actinomadura , Streptomyces and other bacteria was found to be associated with the metabolites profile of SYQ roots. The findings suggest that the upregulation of rutin and hesperetin may contribute to the high bioactive constituent in SYQ roots. These results provide better understanding of the metabolite accumulation pattern in SYQ, and also provide a solution for enhancing the quality of SYQ by application of suitable microbial consortia.
... Soil macrofauna have strong impacts on the mitigation of runoff and soil loss (Bétard, 2021;Bottinelli et al., 2015;Brussaard et al., 2007). Most soil erosion studies take into account the activities of earthworms and termites, "ecosystem engineers" that can greatly modify soil surface features. ...
Soil erosion on agricultural land is a major threat for food and raw materials production. It has become a major concern in rubber (Hevea brasiliensis) plantations introduced on sloping ground. Alternative agroecological crop management practices must be investigated. One aim of our study was to assess the ability of logging residues (i.e., trunks, branches, leaves and stumps of a clearcut plantation) and of legume cover (Pueraria phaseoloides) to mitigate N, P and K losses through runoff and soil detachment in a young rubber plantation. The other aim was to investigate the relationships of these nutrient losses with soil structure and soil macrofauna diversity. Runoff and soil loss were monitored for 3 years using 1-m2 plots under different practices as regards the management of logging residues and the use or not of a legume. The monitoring started when rubber trees were one-year-old. The planting row, where soil was bare, was the hotspot of soil erosion, with an average runoff of 832 mm y−1 and soil loss of 3.2 kg m−2 y−1. Sowing a legume in the inter-row reduced runoff and soil loss by 88 % and 98 % respectively, compared to bare soil. Spreading logging residues as well as growing a legume cover almost eliminated runoff and soil detachment (19 mm y−1 and 4 g m−2 y−1 respectively). Nutrient losses were negligible as long as the soil surface was covered by a legume crop, with or without logging residues. Total N loss from soil detachment ranged from 0.02 to 0.2 g m−2 y−1, for example. Spreading logging residues in the inter-rows significantly improved soil structure and soil macrofauna diversity compared to bare soil. Nutrient losses from runoff and soil detachment were negatively correlated with improved soil structure and soil macrofauna diversity. We recommend investigating alternative ways to manage planting rows.
... Numerous studies have shown that the quantitative criterion of soil fertility is the content of saprophytic and pathogenic bacteria and fungi in specifc proportions in one gram of soil [62,63]. It has also been shown that water availability and soil moisture have a signifcant efect on the activity of soil microbes [64,65]. ...
Soil bacterial and fungal communities were investigated in relation to soil type and farm management practices after vegetation harvesting in autumn. Soils from felds cultivated with Phaseolus vulgaris (bean) and Pyrus comminus (pear) and nonarable, natural areas were studied. Microbial diversity was analysed using cultivation-dependent methods (isolation of pure cultures) and cultivation-independent methods (direct extraction of DNA from soil, followed by PCR amplifcation of the 16S rRNA and 18S rRNA genes). Te use of cultivation-dependent methods revealed that there were no diferences in the biodiversity of the soil bacterial and fungal communities between felds cultivated with bean plants and pear trees. However, the use of cultivation-independent methods showed that there were clear soil and crop type-specifc efects on the composition of the soil bacterial and fungal communities. Te density of the bacterial population was two times higher in northern mountain-valley serozem (NMVS) soil samples than in light chestnut (LC) soil samples. In contrast, the densities of the fungal communities were almost equal in the studied soil types. Te density of the actinomycetes community was almost two times higher in LC soil than in NMVS soil under bean plants. Te Shannon index values showed that the bacterial biodiversity in the NMVS soil samples was greater than that in the LC soil samples. Soils under fallow appeared to have diverse bacterial communities that mainly consisted of local au-tochthonous microfora and a small amount of zymogenic microfora (since fresh plant residue does not enter the soil). Te Shannon index results revealed two interesting facts: (1) the soil bacterial community was highly diverse in soils that supported bean plants and (2) the soil fungal biodiversity was high under pear trees in both soil types.
... There is evidence that soil biodiversity confers stability to stress and disturbance, although the mechanisms are not yet fully understood (Brussard et al., 2007). Fertilization management has been found to influence soil microbial communities in agroecosystems (Zhang et al., 2020). ...
... Soil constitutes one of the most ecologically diverse habitats on our planet, comprising a higher level of biodiversity per unit area compared to biodiversity found above the ground. Soil contains the majority of the biodiversity found in agricultural systems [1]. These soil organisms engage in various interactions with each other as well as with plants and small animals, thereby creating a complex network of biological processes. ...
Aim: Soil represents one of the most diverse habitats found on our planet. Soil organisms play crucial roles within ecosystems by exerting influence over physical properties and processes, as well as contributing to carbon and energy fluxes and the cycling of nutrients. The activity and composition of soil organisms are significantly impacted by land use and land management practices. In this study, we examined the predominant functional groups present in soil two different soil management systems viz., organic and integrated nutrient management (INM).
... Soil constitutes one of the most ecologically diverse habitats on our planet, comprising a higher level of biodiversity per unit area compared to biodiversity found above the ground. Soil contains the majority of the biodiversity found in agricultural systems [1]. These soil organisms engage in various interactions with each other as well as with plants and small animals, thereby creating a complex network of biological processes. ...
Aim: Soil represents one of the most diverse habitats found on our planet. Soil organisms play crucial roles within ecosystems by exerting influence over physical properties and processes, as well as contributing to carbon and energy fluxes and the cycling of nutrients. The activity and composition of soil organisms are significantly impacted by land use and land management practices. In this study, we examined the predominant functional groups present in soil two different soil management systems viz., organic and integrated nutrient management (INM). Methods: We collected soil samples from coconut-based cropping systems under organic soil management and integrated nutrient management. Soil samples were characterised for soil macrofauna, mesofauna, microfauna and microflora. Results: The presence of soil macrofauna, mesofauna, microfauna, and microflora was more pronounced under organic management. Furthermore, the PERMANOVA analysis indicated that while management practices did not significantly impact community dissimilarity in the study area, the depth of the soil did have a significant influence. Conclusion: Although the PERMANOVA analysis within the light conditions examined, revealed that the influence of management practices on community dissimilarity was not statistically significant, it was noted that organic management led to an enhancement in soil biodiversity. The results of this study offer a comprehensive evaluation of the manner in which the organic management and INM practices influence the biodiversity of the soil.
... The effects of SMF on the soil ecosystem are indispensable. Of which, the interacting effect of SMF with microorganisms, contributes to nutrient cycling (Wagg et al. 2014), erosion control through stabilizing soil aggregates (Brussaard et al. 2007), and soil carbon storage (Lubbers et al. 2013). Moreover, the SMF have the greatest potential to modify the soil environment through their activities (Jouquet et al. 2006). ...
The conversion of natural lands to agricultural uses is a significant threat to soil biodiversity. Within agriculture, monoculture based systems are the most common which often result in low biodiversity because they impact the abundance, diversity, and composition of soil macrofauna (SMF). The objective of this paper was to analyze SMF abundance and diversity across different agroforestry practices (AFP) in the drylands of southern Ethiopia. The soil monolith and soil samples were collected from homegarden, cropland, woodlot, and trees on soil and water conservation based AFP using the standard Tropical Soil Biology and Fertility Institute manual, and the identification was done based on morphological characteristics and standard identification keys. The abundance, occurrence, and community composition of SMF were significantly different across the different AFPs (P < 0.05). In this study, 378 SMF belonging to 13 families, including unnamed were identified. The soil ecosystem of AFP was dominated by earthworms (relative abundance = 0.43), followed by termites (relative abundance = 0.12). The homegarden AFP type had a significantly higher number of SMF occurrence index of 46.03 (174), followed by woodlot, 26.72 (101) practices, and the lowest was recorded under cropland, 12.70 (48). The abundance, diversity, richness, and similarity of SMF were significantly related to soil total nitrogen and organic carbon. Phosphorus and pH were significantly related to the abundance and richness of SMF. The homegarden and woodlot AFP types were suitable for SMF biodiversity conservation.
... The agricultural sciences have shown that crop and animal breeding can select for genes to increase agricultural productivity (e.g., Cooper et al., 2001). Crop diversity, in both space and time, can enhance nutrient use efficiency, and a diverse soil community may regulate tighter nutrient cycling, reduce pests and diseases, and improve soil structure (e.g., Brussaard et al., 2007). Ecological research has shown that biodiversity can increase the stability of grassland ecosystems (Loreau et al., 2002), which has implications for the management of pastures for livestock production. ...
... Also, the WMM and WSM systems with greater crop rotation diversity usually tend to create diverse residues and root exudates, thereby increasing resource requirement complementary and utilization availability for supporting and maintaining ecosystem services (Andrade et al., 2015;Isbell et al., 2017;D'Acunto et al., 2018). As demonstrated, there were beneficial effects of increasing microbial diversity on agroecosystem services and sustainability (Brussaard et al., 2007;Guzman et al., 2021). Consequently, adopting cropping systems to increase microbial diversity may require the use of specific crop combinations that can affect soil microbial diversity more than others. ...
Supporting food security while maintaining ecosystem sustainability is one of the most important global challenges for humanity. Optimization of cropping systems is expected to promote the ecosystem services of agroecosystems. Yet, how and why cropping system influences the trade‐offs between economic profitability and multiple ecosystem services remain poorly understood.
We investigate the influence of six cropping systems on trade‐offs between economic profitability and multiple ecosystem services after considering 36 agricultural ecosystem properties using field experiment data from 2020 to 2022.
We show that designing cropping system is a critical tool to closing the gap between ecosystem sustainability and commercial profitability. Cropping system with three harvests within 2 yr had higher performance in overall ecosystem multiple services through enhancement of supporting, regulating, and economic performance without compromising provisioning compared with four other systems. These systems diminished the trade‐off among multiple services, resulting in a ‘win‐win’ situation for economics and multiple services. By contrast, the monoculture and double cropping systems lead to a strong trade‐off between pairwise services including ecosystem health and profitability.
Our work illustrates the substantial potential of rotation systems with three harvests within 2 yr in enforcing ecosystem services and closing the trade‐offs among multiple agricultural ecosystem services.
... The potential mechanisms for their changes are indeed intricate (Hao et al., 2022a). Other unforeseen factors may also affect the PUE and SWUE of vegetation, including elements such as pests and diseases, wildfires (Mkhabela et al., 2009) and soil salinization (Brussaard et al., 2007). The response of PUE and SWUE to divergent driving factors varies considerably among different types of vegetation. ...
... For quite some time by now, the importance of soil biodiversity in soil quality has been recognized [1,2]. Many agricultural techniques are currently employed to sustain agricultural soils, including managing soil biodiversity by reduced, minimal, or no tillage in attempts to partially reconcile agricultural production and biodiversity. ...
Managing soil biodiversity using reduced tillage is a popular approach, yet soil bacteriobiomes in the agroecosystems of Siberia has been scarcely studied, especially as they are related to tillage. We studied bacteriobiomes in Chernozem under natural steppe vegetation and cropped for wheat using conventional or no tillage in a long-term field trial in the Novosibirsk region, Russia, by using the sequence diversity of the V3/V4 region of 16S rRNA genes. Actinobacteria, Acidobacteria, and Proteobacteria summarily accounted for 80% of the total number of sequences, with Actinobacteria alone averaging 51%. The vegetation (natural vs. crop) and tillage (ploughed vs. no-till) affected the bacterial relative abundance at all taxonomic levels and many taxa, e.g., hundreds of OTUs. However, such changes did not translate into α-biodiversity changes, i.e., observed and potential OTUs’ richness, Shannon, and Simpson, excepting the slightly higher evenness and equitability in the top 0–5 cm of the undisturbed soil. As for the β-biodiversity, substituting conventional ploughing with no tillage and maintaining the latter for 12 years notably shifted the soil bacteriobiome closer to the one in the undisturbed soil. This study, presenting the first inventory of soil bacteriobiomes under different tillage in the south of West Siberia, underscores the need to investigate the seasonality and longevity aspects of tillage, especially as they are related to crop production.
... N mineralisation) will enable us to better understand the role of soil biota, in general, and biodiversity and soil microbial community structure, in particular, in protecting soil ecosystems against disturbances. This, in turn, is essential to ensuring sustained productivity of agricultural production systems (Coleman et al., 2004;Brussaard et al., 2007). Although we are able to appreciate the significance of microorganisms in the soil we have little information on the 2 importance of microbial diversity in the functioning of soil systems and most research suggests that the relationships are neither consistent nor direct (Nannipieri et al., 2003;Brussaard et al., 2004). ...
... Investigating these dynamics in a different climate, comprehensively analyzing the entire arthropod community, and testing the impacts of both silage tarps and clear plastic tarps are therefore needed to expand knowledge around tarps. As well, soil arthropods' roles in providing key ecosystem services for agriculture, such as controlling pests (Kromp, 1999;Lang, 2003;Schmidt et al., 2003;van Lenteren et al., 2018) and improving soil health (Lavelle et al., 2006;Brussaard et al., 2007;Briones, 2018), further emphasize the importance of understanding tarps' impacts on this community. ...
... Agronomic Impact: Mulches maintain a humid environment at the soil surface. This can be ideal for the proliferation of certain pests, such as slugs and snails, and even some soil-borne pathogens [73]. Socio-Economic Implications: Proliferation of pests can lead to reduced yields, necessitating increased investment in pest control measures, and could adversely impact farmer profitability. ...
Environmental risk assessments require high quality toxicity data to establish protective thresholds. The chronic effects of very hydrophobic organic compounds (VHOCs) in soils are often difficult to determine because multiple processes (e.g. sorption, volatilization, biodegradation) can complicate the interpretation of results. We have developed a standardized soil dosing and aging procedure for assessing bioavailability of high logK ow VHOCs in a synthetic soil surrogate, and then used it to evaluate the toxicity of high logK ow VHOCs across a range of test substance concentrations and soil organic carbon content. The soil preparation protocol resulted in relatively stable freely dissolved concentrations of test substance compared to bulk soil concentrations with some losses likely due to volatility and biodegradation. This dosing method wasused in a chronic terrestrial plant toxicity bioassay to evaluate the potential toxicity of VHOCs on complex reproductive endpoints like inflorescence and seed bud formation. Testing included common hydrocarbons and three very hydrophobic lubricant substances (logKow > 10). The toxicity data were used to evaluate existing predicted no effect concentrations (PNEC) that had originally been derived without these higher order chronic plant endpoints. The initial exposure concentrations were set at the independently-derived PNECs to provide an independent validation of the PNEC framework. This evaluation was performed to expand the domain of applicability of the PNEC to VHOCs and for the chronic terrestrial plant endpoints. We saw no effects on plant biomass or inflorescence production at these low exposure concentrations, demonstrating that the established PNEC is protective of long term plant health. The results of the present study confirm that the new dosing method is fit for purpose, and that the existing PNEC framework can be extended to chronic plant endpoints for VHOCs.
Industrialization and urbanization increased the use of chemicals in agriculture, vehicular emissions, etc., and spoiled all environmental sectors. It causes various problems among living beings at multiple levels and concentrations. Phytoremediation and microbial association are emerging as a potential method for removing heavy metals and other contaminants from soil. The treatment uses plant physiology and metabolism to remove or clean up various soil contaminants efficiently. In recent years, omics and artificial intelligence have been seen as powerful techniques for phytobial remediation. Recently, AI and modeling are used to analyze large data generated by omics technologies. Machine learning algorithms can be used to develop predictive models that can help guide the selection of the most appropriate plant and plant growth–promoting rhizobacteria combination that is most effective at remediation. In this review, emphasis is given to the phytoremediation techniques being explored worldwide in soil contamination.
Earth is one of the unique planets of the solar system containing life in the presence of land, air, and water, of which the land is the most important platform for growth and development of plants. The land and water contribute to carry it. The upper crust of land, i.e., solum/soil, bears productive potential. It is a critical resource for food production. Since the twentieth century, intensive farming has substantially deteriorated the soil. Around 33% of soil is already degraded and 90% could become degraded by 2050. The ever-increasing food demand would not allow for lowering intensity or coverage of cultivation; therefore the “Sustainable management” of land resources seems to be the most suitable option. This division of the book evaluated how soil and agroforestry are interconnected concepts that relate to sustainable land use and food production. Agroforestry practices vary depending on the type of environment and needs of the community; however, the characteristic feature is the deliberate management of trees, crops, and animals to achieve multiple benefits. These benefits include increased soil fertility, reduced erosion, improved water quality, increased biodiversity, and increased carbon sequestration. By maintaining year-round surface cover that shields the soil from water and wind erosion, the perennial woody flora used in agroforestry techniques helps to conserve soil. Enhancement of soil organic carbon, available nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) (macronutrients) under different conditions is observed. Even improvement in soil bio-physical condition is also reported in many studies. Soil health is a critical component of agroforestry, as the soil provides the foundation for the entire ecosystem. In agroforestry, soil health is often improved through the use of organic matter, such as compost or cover crops, and the reduction of tillage. Both soil and agroforestry land use systems are interlinked and share a complementary relation, i.e., one being responsible in elevating and maintaining the status of another.
The ecological engineering of granular sludge relies on a continuum from microbiological research to process engineering. Designing granular sludge systems for biological nutrient removal should thrive on the 100 years of activated sludge research and practice. Flocs and granules are made of the same guilds of microorganisms that convert nutrients. Granules are suspended biofilm particles that form by self-aggregation of microbes. Granules (0.5–2 mm scale) differ from flocs (10–100+ µm) in metrics and are prone to substrate diffusion limitations. Niches of microbial populations involved in C–N–P conversions establish at different locations along substrate and redox gradients in the architecture of granules, enabling an almost simultaneous removal of all nutrients. Granulation densifies the biomass and increases its concentration for faster volumetric conversions, and more compact bioreactors. Fundamental processes of bioaggregation need to get uncovered in relation to microbial selection and process performances. Deriving microbial ecology principles is important to understand the composition and functioning of the granular sludge ecosystem, and to manage the microbial resource for an efficient granulation and nutrient removal. Reactor engineering relies on a multi-scale knowledge from process to granules, microorganisms, and their metabolisms. Combining systems microbiology, environmental biotechnology, and mathematical modelling enables concepts and methodologies for engineering.
Smart Farming - Integrating Conservation Agriculture, Information Technology, and Advanced Techniques for Sustainable Crop Production is a timely and comprehensive volume that explores the latest advances and opportunities in an emerging field. The book brings together experts from various disciplines to discuss the principles, practices, and technologies of smart farming, and their potential for sustainable agriculture. Topics include the adoption of conservation agriculture, information technology drivers in smart farming management systems, physiological breeding, and nanotechnology applications in smart farming. This book is intended for researchers, policymakers, and practitioners in the field of agriculture who are interested in exploring the latest developments in smart farming and its potential for enhancing crop production, reducing environmental impact, and increasing farmers’ profits.
Agriculture is one of the most important industries in the world. In this context, the importance of Brazil as a strategic country to meet a range of SDG’s targets linked to food security, fighting against hunger, and poverty reduction is undeniable. This study aimed to highlight the production and dissemination of scientific research developed by Brazilian institutions, and to identify prominent authors and institutions based on articles related to sustainability, agriculture, livestock, and agribusiness. A bibliometric analysis was developed based on a sample of 3139 documents published between 2000 and 2022, comprising 21,380 authors that were then analyzed using the Biblioshiny package. As result, the term “sustainability” showed growth as it branched out to semantically similar terms, such as “sustainable agriculture” and “sustainable intensification”; and “crop–livestock integration” and “agroforestry” were highlighted as important in the development of future research. The majority of documents were produced by the University of São Paulo (~33%), the State University of São Paulo (~15%), and the Federal University of Rio Grande do Sul (~11%), suggesting that their researchers could act as coordinators in future research through the formation of multi-collaborative groups to jointly lead to the participatory elaboration of public policies that promote more sustainable paths for agricultural production.
Background
Tropical soils are characterized by low soil organic carbon (SOC) contents, which can negatively impact soil fertility, water retention, overall agricultural productivity, and food security.
Objective
This paper aimed to review and synthesize the current body of literature on the restoration of SOC in tropical soils.
Methods
A total of about 152 related articles were downloaded from electronic journal databases using search keywords, such as organic carbon (OC), conservation tillage, intercropping, biochar, and tropical soil. We discussed conservation tillage practices, such as reducing soil disturbance and respiration from the soils, as a means to promote soil OC sequestration. We also highlighted the importance of crop residue retention, which not only increases organic matter inputs and soil nutrients but also promotes soil water retention and reduces soil erosion.
Results
Cover crops and crop rotation are identified as effective practices to cover bare ground during planting seasons, reduce erosion, and prevent nutrient losses through leaching and runoff. Additionally, we review the role of fertilizer application, manure and compost application, intercropping, agroforestry, and biochar as strategies to enhance OC content in tropical soils. We highlight the benefits of incorporating organic amendments, such as manure and compost, to improve soil structure and water-holding capacity. Furthermore, we discuss the potential of biochar, a carbon-rich material produced from biomass pyrolysis, as a strategy to sequester OC in tropical soils.
Conclusion
Overall, this review provides insights into various strategies that can be implemented to increase the OC content of tropical soils, which can have multiple benefits for soil health, agricultural productivity, and climate change mitigation. Further research and implementation of these practices can contribute to mitigating climate change, conserving soil resources, and promoting sustainable agriculture in tropical regions.
Earthworms play a crucial role in the invertebrate community of soil by contributing to the belowground biomass and biogeochemical cycle. Environmental stresses, such as human activities and land use changes, have been found to negatively affect their abundance and diversity. To investigate the impact of agricultural land use and pastures on earthworms' genetic diversity in the Northern Zagros Mountains, we used COI molecular marker and DNA barcoding approaches. We collected earthworm specimens from four farmland sites and six pastures and assessed the abundance and species composition of earthworm communities across the two land uses using quadrat sampling. Using the barcoding method, we identified 13 molecular operational taxonomic units (MOTUs) among the captured earthworms. Our results showed that the number of total MOTUs, density, and earthworm communities differed significantly between the two land uses. We also found that pastures had more abundant earthworms, while farmlands had greater diversity. The diversity of OTUs in the Lumbricidae family was dominant in the agricultural system. Overall, the population of invasive earthworm species in cultivation systems is influenced by chemical inputs and organic materials from plant residues, cover crops, manure, or organic fertilizers. Given the rapid rate of land use change worldwide, especially in Iran, it is crucial to understand the impact of disturbances on earthworms.
Citation: Möth, S.; Khalil, S.; Rizzoli, R.; Steiner, M.; Forneck, A.; Bacher, S.; Griesser, M.; Querner, P.; Winter, S. Inter-Row Management and Clay Content Influence Acari and Collembola Abundances in Vineyards. Horticulturae 2023, 9, 1249. Abstract: Viticulture is a perennial cropping system that provides large inter-row space as a non-crop habitat for a range of different taxa. Extensive vegetation management has been shown to increase biodiversity and ecosystem service provision in vineyards. Important soil ecosystem services are decomposition, nutrient cycling, and pest regulation provided by the mesofauna (e.g., Acari and Collembola). However, studies investigating the effects of inter-row management on soil mesofauna are scarce. We studied the effect of inter-row management intensity (complete vegetation cover, alternating vegetation cover, and bare ground) and local pedoclimatic conditions on Acari and Collembola in nine Austrian vineyards. Our results showed that the clay content of the soil was the most important factor and increased the abundances of both analyzed taxa. Complete and alternating vegetation cover increased their abundance in comparison to bare ground management. Higher soil respiration slightly contributed to higher abundances of those two taxa in both years. In conclusion, besides the positive effects of the clay content in the soil, complete and alternating vegetation cover are feasible management practices for increasing soil mesofauna in vineyards.
Even if their impact is often underestimated, yeasts and yeast-like fungi represent the most prevalent eukaryotic members of microbial communities on Earth. They play numerous roles in natural ecosystems and in association with their hosts. They are involved in the food industry and pharmaceutical production, but they can also cause diseases in other organisms, making the understanding of their biology mandatory. The ongoing loss of biodiversity due to overexploitation of environmental resources is a growing concern in many countries. Therefore, it becomes crucial to understand the ecology and evolutionary history of these organisms to systematically classify them. To achieve this, it is essential that our knowledge of the mycobiota reaches a level similar to that of the bacterial communities. To overcome the existing challenges in the study of fungal communities, the first step should be the establishment of standardized techniques for the correct identification of species, even from complex matrices, both in wet lab practices and in bioinformatic tools.
Biochar effects are strongly dependent on its properties. Biochar improves physical soil properties by decreasing bulk density and increasing medium and large aggregates, leading to faster and deeper water infiltration and root growth. Improvement of the chemical properties of soil is connected with pH neutralization of acidic soils, increase of cation exchange capacity and base saturation, providing a larger surface for sorption of toxicants and exchange of cations. Biochar increases the stocks of macro- and micronutrients in soil and remains sufficient for decades. Biochar effects on (micro)biological properties are mainly indirect, based on the improvements of habitat conditions for organisms, deeper root growth providing available C for larger soil volume, higher crop yield leading to more residues on and in the topsoil, better and deeper soil moisture, supply of all nutrients, and better aeration. Along with positive, negative effects of biochar while used as a soil conditioner are discussed in the review: presence of PAH, excessive amounts of K, Ca and Mg, declination of soil pH. In conclusion, despite the removal of C from the biological cycle by feedstock pyrolysis, the subsequent application of biochar into soil increases fertility and improves physical and chemical properties for root and microbial growth is a good amendment for low fertility soils. Proper use of biochar leads not only to an increase in crop yield but also to effective sequestration of carbon in the soil, which is important to consider when economically assessing its production. Further research should be aimed at assessing and developing methods for increasing the sequestration potential of biochar as fertilizer.
Modern agriculture, especially monocultures, is increasingly blamed by proponents of agroecology for loss of biodiversity in agroecosystems through loss of natural vegetation and crop genetic diversity. However, loss of natural vegetation to agriculture has slowed in recent years, and the claim for 75% loss of crop genetic diversity due to the widespread use of improved crop varieties lacks evidence. The main objective of this perspective paper is to identify and analyze the kinds of diversity already developed by agricultural research in the context of their function, need and relevance to particular agroecological elements and principles related to biodiversity. The paper shows that biodiversity is already incorporated into agroecosystems in a multitude of ways such as improved crop varieties with functional traits; crop mixtures and dual-purpose crops in monocultures; inter-crops, strip crops or relay crops; cover crops; crop rotations; field margins; landscape diversification; crop-livestock systems; and agroforestry. Emphasis is also given to crop-associated biodiversity above ground and soil biodiversity. The paper highlights that more research is needed to (a) breed crops for multi-cropping systems; (b) improve understanding of how components of diversity interact within or across systems and scales; (c) understand the role of soil biodiversity in soil function; and (d) successfully use crop-associated biodiversity to manage pests and beneficial organisms. In the future, the promotion of agroecological principles should incorporate inputs from crop breeders, agronomists, ecologists and crop protectionists for the benefit of farmers, or such principles will remain aspirational.
Old-growth forest of the Hoh River Valley, Olympic National Park, Washington (U.S.A.). For decades the U.S. Pacific Norwest has been a center of controversy over logging and endangered species. This special section explores progress made by the Northwest Forest Plan?a global example of land-use planning?a decade after it was established to end the stalemate over logging and endangered species. Authors include some of the key architects involved in its creation and implementation. Photo by Kevin Schafer.
In: Wall DH (ed), Sustaining Biodiversity and Ecosystem Services in Soils and Sediments
While soil quality encompasses physical and chemical besides biological characteristics, soil health is primarily an ecological characteristic. Ecosystem health has been defined in terms of ecosystem stability and resilience in response to a disturbance or stress. We therefore, suggest that indicators for soil health could be found by monitoring responses of the soil microbial community to the application of different stress factors at various intensities. The amplitude of a response and time to return to the current state before application of stress could serve as measures of soil health. Root pathogens are an integral part of soil microbial communities, and the occurrence of epiphytotics forms an indication of an ecosystem in distress. Disease suppression can be viewed as a manifestation of ecosystem stability and health. Thus, indicators for soil health could possibly also function as indicators for disease suppressiveness. Previously suggested indicators for soil health and disease suppression have mainly been lists of variables that were correlated to more or less disturbed soils (ranging from conventional to organic agricultural soils, grassland and forest soils) or to conduciveness to disease. We suggest a systematic ecological approach to the search for indicators for soil health and disease suppression, namely, measuring biological responses to various stress factors and the time needed to return to the current state.
This book contains 18 chapters dealing with management oriented approach by identifying key issues in soil quality and management options to enhance the sustainability of modern agriculture. Topics covered include major plant nutrients (N, P, K), soil acidity, soil organic matter, soil microbial biomass and biodiversity, subsoil compaction, soil structure degradation, erosion, pesticides, industrial and urban waste. In-depth treatments of the soil quality concepts, its history, and its applicability in research and land use planning in Developed and Developing Countries are also discussed. This book will be of significant interest to post-graduate students and researchers in agronomy and in soil, crop and environmental sciences, and to stakeholders involved in issues related to land use and agricultural development.
"Propositions" ([1] leaf) inserted. Thesis (doctoral)--Universiteit Leiden, 2005. Vita. Includes bibliographical references (p. 141-157).
The functioning and stability of terrestrial ecosystems are determined by plant biodiversity and species composition. However, the ecological mechanisms by which plant biodiversity and species composition are regulated and maintained are not well understood. These mechanisms need to be identified to ensure successful management for conservation and restoration of diverse natural ecosystems. Here we show, by using two independent, but complementary, ecological experiments, that below-ground diversity of arbuscular mycorrhizal fungi (AMF) is a major factor contributing to the maintenance of plant biodiversity and to ecosystem functioning. At low AMF diversity, the plant species composition and overall structure of microcosms that simulate European calcareous grassland fluctuate greatly when the AMF taxa that are present are changed. Plant biodiversity, nutrient capture and productivity in macrocosms that simulate North American old-fields increase significantly with increasing AMF-species richness. These results emphasize the need to protect AMF and to consider these fungi in future management practices in order to maintain diverse ecosystems. Our results also show that microbial interactions can drive ecosystem functions such as plant biodiversity, productivity and variability.
Although the effect of biodiversity on ecosystem functioning has become a major focus in ecology, its significance in a fluctuating environment is still poorly understood. According to the insurance hypothesis, biodiversity insures ecosystems against declines in their functioning because many species provide greater guarantees that some will maintain functioning even if others fail. Here we examine this hypothesis theoretically. We develop a general stochastic dynamic model to assess the effects of species richness on the expected temporal mean and variance of ecosystem processes such as productivity, based on individual species' productivity responses to environmental fluctuations. Our model shows two major insurance effects of species richness on ecosystem productivity: (i) a buffering effect, i.e., a reduction in the temporal variance of productivity, and (ii) a performance-enhancing effect, i.e., an increase in the temporal mean of productivity. The strength of these insurance effects is determined by three factors: (i) the way ecosystem productivity is determined by individual species responses to environmental fluctuations, (ii) the degree of asynchronicity of these responses, and (iii) the detailed form of these responses. In particular, the greater the variance of the species responses, the lower the species richness at which the temporal mean of the ecosystem process saturates and the ecosystem becomes redundant. These results provide a strong theoretical foundation for the insurance hypothesis, which proves to be a fundamental principle for understanding the long-term effects of biodiversity on ecosystem processes.
Human alteration of the global environment has triggered the sixth major
extinction event in the history of life and caused widespread changes in the
global distribution of organisms. These changes in biodiversity alter ecosystem
processes and change the resilience of ecosystems to environmental change.
This has profound consequences for services that humans derive from ecosystems.
The large ecological and societal consequences of changing biodiversity should
be minimized to preserve options for future solutions to global environmental
problems.
Increasing evidence that the strengths of interactions among populations in biological communities form patterns that are crucial for system stability requires clarification of the precise form of these patterns, how they come about, and why they influence stability. We show that in real food webs, interaction strengths are organized in trophic loops in such a way that long loops contain relatively many weak links. We show and explain mathematically that this patterning enhances stability, because it reduces maximum "loop weight" and thus reduces the amount of intraspecific interaction needed for matrix stability. The patterns are brought about by biomass pyramids, a feature common to most ecosystems. Incorporation of biomass pyramids in 104 food-web descriptions reveals that the low weight of the long loops stabilizes complex food webs. Loop-weight analysis could be a useful tool for exploring the structure and organization of complex communities.
The consequences of biodiversity loss for ecosystem functioning and ecosystem services have aroused considerable interest during the past decade. Recent work has focused mainly on the impact of species diversity within single trophic levels, both experimentally and theoretically. Experiments have usually showed increased plant biomass and productivity with increasing plant diversity. Changes in biodiversity, however, may affect ecosystem processes through trophic interactions among species as well. An important current challenge is to understand how these trophic interactions affect the relationship between biodiversity and ecosystem functioning. Here we present a mechanistic model of an ecosystem with multiple trophic levels in which plants compete for a limiting soil nutrient. In contrast to previous studies that focused on single trophic levels, we show that plant biomass does not always increase with plant diversity and that changes in biodiversity can lead to complex if predictable changes in ecosystem processes. Our analysis demonstrates that food-web structure can profoundly influence ecosystem properties.
An increasing interest has emerged with respect to the importance of microbial diversity in soil habitats. The extent of the diversity of microorganisms in soil is seen to be critical to the maintenance of soil health and quality, as a wide range of microorganisms is involved in important soil functions. This review focuses on recent data relating how plant type, soil type, and soil management regime affect the microbial diversity of soil and the implication for the soil's disease suppressiveness. The two main drivers of soil microbial community structure, i.e., plant type and soil type, are thought to exert their function in a complex manner. We propose that the fact that in some situations the soil and in others the plant type is the key factor determining soil microbial diversity is related to the complexity of the microbial interactions in soil, including interactions between microorganisms and soil and microorganisms and plants. A conceptual framework, based on the relative strengths of the shaping forces exerted by plant and soil versus the ecological behavior of microorganisms, is proposed.
Knowledge of the interactions between organisms within trophic groups is important for an understanding of the role of biodiversity in ecosystem functioning. We hypothesised that interactions between bacterivorous nematodes of different life history strategies would affect nematode population development, bacterial community composition and activity, resulting in increased N mineralization. A microcosm experiment was conducted using three nematode species (Bursilla monhystera, Acrobeloides nanus and Plectus parvus). All the nematode species interacted with each other, but the nature and effects of these interactions depended on the specific species combination. The interaction between B. monhystera and A. nanus was asymmetrically competitive (0,-), whereas that between B. monhystera and P. parvus, and also A. nanus and P. parvus was contramensal (+, -). The interaction that affected microcosm properties the most was the interaction between B. monhystera and P. parvus. This interaction affected the bacterial community composition, increased the bacterial biomass and increased soil N mineralization. B. monhystera and P. parvus have the most different life history strategies, whereas A. nanus has a life history strategy intermediate to those of B. monhystera and P. parvus. We suggest that the difference in life history strategies between species of the same trophic group is of importance for their communal effect on soil ecosystem processes. Our results support the idiosyncrasy hypothesis on the role of biodiversity in ecosystem functioning.
The loss of biodiversity can have significant impacts on ecosystem functioning, but the mechanisms involved lack empirical
confirmation. Using soil microcosms, we show experimentally that functional dissimilarity among detritivorous species, not
species number, drives community compositional effects on leaf litter mass loss and soil respiration, two key soil ecosystem
processes. These experiments confirm theoretical predictions that biodiversity effects on ecosystem functioning can be predicted
by the degree of functional differences among species.
A common pattern emerging from studies on the relationship between plant diversity and ecosystem functioning is that productivity increases with diversity. Most of these studies have been carried out in perennial grasslands, but many lasted only two growing seasons or reported data from a single year. Especially for perennial plant communities, however, the long-term effects of diversity are important. The question whether interactions between few species or among many species lead to increased productivity remained largely unanswered. So far, the main mechanism addressed is the increased input of nitrogen by nitrogen-fixing legumes. We report that other mechanisms can also generate strong increases of productivity with diversity. Results from 4 consecutive years of a plant diversity experiment without legumes show that a positive relationship between plant species richness and productivity emerged in the second year and strengthened with time. We show that increased nutrient use efficiency at high species richness is an important underlying mechanism. This mechanism had not been discussed in earlier studies. Furthermore, our results suggest that complementary nutrient uptake in space and time is important. Together, these mechanisms sustain consistently high productivity at high diversity.
This book provides a synthesis of plant-soil-plant interactions from the plot to landscape scale. It focuses on the process level, which is relevant to many types of multispecies agroecosystems (agroforestry, intercropping and others). It also links basic research to practical application (and indigenous knowledge) in a wide range of systems with or without trees, and considers implications of below-ground interactions for the environment and global change issues. The contents include root architecture and dynamics, plant-soil biota interactions, soil biodiversity and food webs, water and nutrient cycling, and the necessary linkage to modelling approaches.
We propose that a holistic view be taken to the study and implementation of ecological research into soils, soil organisms and plant growth. This builds upon the spatial and temporal aspects of soil physical and biological characteristics at the micro-and macroaggregate scales. This has major implications for the interactions of the soil biota and also for the possibilities of soil organic matter (SOM) dynamics, including gradual accumulation of SOM across decades and centuries. One of the key integrating factors in the role of soil biota in plant nutrition is the centrality of detrital and soil food webs in fostering nutrient cycling and ecosystem stability. We conclude with a five-dimension approach to studying key factors in soil biological interactions that affect plant nutrition and also long-term carbon balance in natural and agricultural ecosystems. Abstract We propose that a holistic view be taken to the study and implementation of ecological research into soils, soil organisms and plant growth. This builds upon the spatial and temporal aspects of soil physical and biological characteristics at the micro-and macroaggregate scales. This has major implications for the interactions of the soil biota and also for the possibilities of soil organic matter (SOM) dynamics, including gradual accumulation of SOM across decades and centuries. One of the key integrating factors in the role of soil biota in plant nutrition is the centrality of detrital and soil food webs in fostering nutrient cycling and ecosystem stability. We conclude with a five-dimension approach to studying key factors in soil biological interactions that affect plant nutrition and also long-term carbon balance in natural and agricultural ecosystems.
We propose that a holistic view be taken to the study and implementation of ecological research into soils, soil organisms and plant growth. This builds upon the spatial and temporal aspects of soil physical and biological characteristics at the micro-and macroaggregate scales. This has major implications for the interactions of the soil biota and also for the possibilities of soil organic matter (SOM) dynamics, including gradual accumulation of SOM across decades and centuries. One of the key integrating factors in the role of soil biota in plant nutrition is the centrality of detrital and soil food webs in fostering nutrient cycling and ecosystem stability. We conclude with a fi ve-dimension approach to studying key factors in soil biological interactions that affect plant nutrition and also long-term carbon balance in natural and agricultural ecosystems.
Augé, R. M. 2004. Arbuscular mycorrhizae and soil/plant water relations. Can. J. Soil Sci. 84: 373-381. The water relations of arbuscular mycorrhizal (AM) plants have been compared often. However, virtually nothing is known about the comparative water relations of AM and nonAM soils or about the relative influence of AM colonization of soil vs. AM colonization of plants on host water balance. In this review, I summarize findings that support the assertion that colonization of soil may play as impor- tant a role as colonization of roots regarding how AM symbiosis affects the water relations of host plants. We observed a slight but significant AM effect on the soil moisture characteristic curve of a Sequatchie fine sandy loam following 7 mo of mycor- rhization by Glomus intraradices/Vigna unguiculata. In a separate study, few AM effects on either the wet or dry hysteretic curves were discernible after 12 mo of mycorrhization by G. intraradices or Gigaspora margarita on roots of Phaseolus vulgaris. Using myc- bean mutants, we determined that about half of the considerable promotion of stomatal conductance by G. intraradices and Gi. margarita was attributable to soil colonization and about half to plant colonization. A path analysis modeling approach revealed that soil hyphal colonization had larger direct and total effects on dehydration tolerance of bean than did root hyphal col- onization or several other soil or plant variables.
Soil-arthropod and earthworm densities (number m-2) were higher (P < 0.05) under no-tillage than conventional tillage practices. Enchytraeid worms were higher in conventional tillage. Two predaceous groups, ground beetles (Carabidae: Coleoptera) and spiders (Araneae), comprised more than one-half of all soil macroarthropods collected. All major microarthropod suborders (Oribatids, Prostigmatids, Mesostigmatids, and the order Collembola) were higher (P < 0.01) under no-tillage than conventional tillage. High soil-arthropod and earthworm densities under no-tillage systems suggest an expanded and beneficial involvement for these soil fauna in crop-residue-decomposition processes.
We investigated the role of water use in a Mediterranean grassland, in which diversity was experimentally manipulated, and a positive relationship was observed between plant species richness and productivity. Soil moisture patterns and stable carbon isotope ratios (δ13C) in leaves indicated greater water use by plants growing in species-rich mixtures compared to monocultures. These results suggest that complementarity or facilitation may be the mechanism responsible for the positive relationship between plant diversity and ecosystem processes.
Functional stability, measured in terms of resistance and resilience of respiration and growth rate of bacteria and fungi, was studied in soils that have been exposed to copper and low pH for more than twenty years. We used treatments, consisting of soil with no or high copper load (0 or 750 kg ha⁻¹) and low or neutral pH (4.0 or 6.1). Stability was examined by applying an additional stress in the form of lead or salt. After addition of lead, respiration (decomposition of freshly added lucerne meal) showed lower resistance at low than at neutral pH and at high copper than at low copper. The most acid and contaminated soil was the least resistant. Respiration showed no resilience after addition of lead. Bacterial growth rate (thymidine incorporation) also showed resistance at low pH but only in soils that were not contaminated with copper.
Ecosystem nutrient use efficiency–the ratio of net primary productivity to soil nutrient supply–is an integrative measure
of ecosystem functioning. High productivity and nutrient retention in natural systems are frequently attributed to high species
diversity, even though some single-species systems can be highly productive and effective at resource capture. We investigated
the effects of both individual species and life-form diversity on ecosystem nutrient use efficiency using model tropical ecosystems
comprised of monocultures of three tree species and polycultures in which each of the tree species was coplanted with species
of two additional life forms. Tree species significantly influenced nutrient use efficiency by whole ecosystems in monocultures;
however, in polycultures, the additional life forms interacted with the influence exerted by the dominant tree. Furthermore,
the presence of the additional life forms significantly increased nutrient uptake and uptake efficiency, but in only two of
the three systems and 2 of the 4 years of the study period. These results indicate that the effect of life-form diversity
on ecosystem functioning is not constant and that there may be temporal shifts in the influence exerted by different components
of the community. Furthermore, although species (and life forms) exerted considerable influence on ecosystem nutrient use
efficiency, this efficiency was most closely related to soil nutrient availability. These findings demonstrate that ecosystem
nutrient use efficiency is an outcome not only of the characteristics of the species or life forms that comprise the system
but also of factors that affect soil nutrient supply. The results argue against the simple upward scaling of nutrient use
efficiency from leaves and plants to ecosystems.
Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for their ecological group classifications, and that earthworm species interactions would affect mineralization through competition and facilitation effects. A mesocosm experiment was conducted to investigate the effect of three earthworm species, representative of different ecological groups (epigeic: Lumbricus rubellus; endogeic: Aporrectodea caliginosa tuberculata; and anecic: Lumbricus terrestris), and their interactions on the bacterial community, and on nitrogen mineralization from 15N-labelled crop residue and from soil organic matter.
Microbial communities differing in biodiversity were established by inoculating sterile agricultural soil with serially diluted soil suspensions prepared from the parent soil. Three replicate communities of each dilution were allowed to establish an equivalent microbial biomass by incubation for 9 months at 15°C, after which the biodiversity–ecosystem function relationship was examined for a range of soil processes. Biodiversity was determined by monitoring cultivable bacterial and fungal morphotypes, directly extracted eubacterial DNA and protozoan taxa. In the context of this study biodiversity relates to the numbers and proportions of different microbial species. Biodiversity decreased by ca. 15, 40 and 60% at each successive dilution step. There was no consistent effect of biodiversity on a range of soil processes measured (incorporation of thymidine and leucine, potential nitrification, nitrate accumulation, respiratory growth response, community level physiological profile and decomposition). Neither was there a direct effect of biodiversity on the variability of the processes, nor on the stability of decomposition when the soils were perturbed by heat or copper. The biodiversity of, and inter-relationships within, the microbial communities was such that the experimental reductions had no direct effects on soil function.
Stability of a soil property to perturbation comprises both resistance and resilience. Resistance is defined as the ability of the soil to withstand the immediate effects of perturbation, and resilience the ability of the soil to recover from perturbation. Functional stability is used here to describe the stability of a biological function to perturbation, rather than the stability of physical structure or chemical properties. The function chosen for this study was the short-term decomposition of added plant residues, and the perturbations were copper and heat stresses. Previous studies had shown that functional stability was reduced greatly in soils with experimentally reduced biodiversity. The objective of this study was to determine the relative sensitivity of functional stability and potential indicators of biological status to detect alteration of field soils by various environmental impacts. Functional stability, protozoan populations and substrate mineralisation kinetics, were measured on paired soils with: high or low plant species diversity; hydrocarbon pollution or not; extensive or intensive agricultural management practices. Substrate mineralisation kinetics were poorly related to the soil’s antecedent conditions and were stimulated significantly by hydrocarbon pollution. Protozoan populations were potentially useful for detecting differences within soil type, but will require greater taxonomic input to be most useful. Functional stability, particularly resistance, was able to quantify differences between and within soils. The potential development of the technique in relation to soil health is discussed.
The prevalence of antibiotic production loci in soil is a key issue of current research aimed to unravel the mechanisms underlying the suppressiveness of soil to plant pathogens. Pyrrolnitrin (PRN) is a key antibiotic involved in the suppression of a range of phytopathogenic fungi. Therefore, field soils from different agricultural regimes, including permanent grassland, arable land under common agricultural rotation and arable land under maize monoculture, were investigated in respect of the prevalence of pyrrolnitrin biosynthetic loci. Primers for detection of the prnD gene were used for initial PCR/hybridisation-based assessments. By this method, evidence was obtained for the contention that PRN production loci were most prevalent in grasslands, however, robust quantitative data were not achieved.To quantify the prevalence of PRN biosynthetic loci, we designed a TaqMan PCR system based on the prnD gene for the real-time quantitative detection of this production locus in soil. The system was found to be specific for prnD sequences from Pseudomonas, Serratia and Burkholderia species. Using pure culture DNA, the prnD gene was detectable down to a level of 60 fg, or approximately 10 gene copies, per amplification reaction. Application of the system to soil DNA spiked with different levels of the target DNA indicated that, in a soil DNA background, specific amplification could be obtained to about the same level of sensitivity.Field soil samples obtained from the different agricultural regimes were then screened for the prevalence of prnD with the real-time PCR system. The quantitative data obtained suggested a strongly enhanced presence of prnD genes in grassland or grassland-derived plots, as compared to the prevalence of this biosynthetic locus in the arable land plots. The implications of these findings are placed in the context of the suppressiveness of soil to phytopathogens, notably Rhizoctonia solani AG3.
In northern Burkina Faso (West Africa), a study was undertaken to explore the possibilities of restoring the infiltration capacity of crusted soils through the stimulation of termite activity. Treatments consisted of the application of a mulch of a mixture of wood and straw without insecticides (resulting in “termite plots”) and the application of the same mulch and an insecticide (Dursban with chloropyrifos as the active ingredient) to prevent termite activity (resulting in “non-termite plots”). Three rainfall simulations of 60 minutes duration with an intensity of 50 mm/h at an interval of 24 hours between the first and the second and 72 hours between the second and third simulation were applied, to study the effect of consecutive showers on termite-modified soil characteristics. Cumulative infiltration amounts, final infiltration rates, soil water content and porosity were larger and bulk density was smaller on termite plots as compared to non-termite plots. This suggests that termites may be an important agent in soil-crust control and in the improvement of soil physical properties in Sahelian ecosystems.
Soil processes are significantly regulated by biological activities. Soil ecosystem engineers (predominantly termites, earthworms and ants) and roots produce biogenic structures, aggregates or pores that determine the structure and architecture of soil. The sum of structures produced by a population or community of invertebrate engineers creates a specific environment defined here as a functional domain. Functional domains are characterized by (i) the nature and spatial array of the biogenic structures, solid aggregates, mounds or constructs and pores of different shapes or sizes; (ii) the specific communities of smaller organisms from the meso- and microfauna and micro-organisms that they host; and (iii) the spatial and temporal scales at which soil processes operate. The regulation of processes caused by the physical organization of the soil environment and the redistribution of organic resources have been described and quantified in several studies. In soil, the relative importance of regulation imposed by ecosystem engineering is likely to be greater than regulation by trophic relationships because of the specific ecological constraints observed in this environment when compared to above-ground conditions.
This paper uses theory and experiments to explore the effects of diversity on stability, productivity, and susceptibility to invasion. A model of resource competition predicts that increases in diversity cause community stability to increase, but population stability to decrease.. These opposite effects are, to a great extent, explained by how temporal variances in species abundances scale with mean abundance, and by the differential impact of this scaling on population vs. community stability. Community stability also depends on a negative covariance effect (competitive compensation) and on overyielding (ecosystem productivity increasing with diversity). A longterm study in Minnesota grasslands supports these predictions.
Models of competition predict, and field experiments confirm, that greater plant diversity leads to greater primary productivity. This diversity-stability relationship results both from the greater chance that a more productive species would be present at higher diversity (the sampling effect) and from the better "coverage" of habitat heterogeneity caused by a broader range of species traits in amore diverse community(the niche differentiation effect). Both effects cause more complete utilisation of limiting resources at higher diversity, which increases resource retention, further increasing productivity. Finally, lower levels of available limiting resources at higher diversity are predicted to decrease the susceptibility of an ecosystem to invasion, supporting the diversity-stability hypothesis. This mechanism provides rules for community assembly and invasion resistance.
In total, biodiversity should be added to species composition, disturbance, nutrient supply, and climate as a major controller of population and ecosystem dynamics and structure. By their increasingly great directional impacts on all of these controllers, humans are likely to cause major longterm changes in the functioning of ecosystems worldwide. A better understanding of these ecosystem changes is needed if ecologists are to provide society with the knowledge essential for wise management of the Earth and its biological resources.
COMMUNITIES of species and their associated biological, chemical and
physical processes, collectively known as ecosystems, drive the Earth's
biogeochemical processes1,2. Currently most ecosystems are
experiencing loss of biodiversity associated with the activities of
human expansion3-5, raising the issue of whether the
biogeochemical functioning of ecosystems will be impaired by this loss
of species6-8. Current ecological knowledge supports a wide
range of views on the subject9-13, but empirical tests are
few9,14-16. Here we provide evidence from direct experimental
manipulation of diversity by over an order of magnitude, using
multi-trophic level communities and simultaneous measures of several
ecosystem processes, that reduced biodiversity may indeed alter the
performance of ecosystems.
This review evaluates evidence of the impact of uncomposted plant residues, composts, manures, and liquid preparations made from composts (compost extracts and teas) on pest and disease incidence and severity in agricultural and horticultural crop production. Most reports on pest control using such organic amendments relate to tropical or and climates. The majority of recent work on the use of organic amendments for prevention and control of diseases relates to container-produced plants, particularly ornamentals. However, there is growing interest in the potential for using composts to prevent and control diseases in temperate agricultural and horticultural field crops and information concerning their use and effectiveness is slowly increasing. The impact of uncomposted plant residues, composts, manures, and compost extracts/teas on pests and diseases is discussed in relation to sustainable temperate field and protected cropping systems. The factors affecting efficacy or such organic amendments in preventing and controlling pests and disease are examined and the mechanisms through which control is achieved are described.
The rehabilitation of vegetation on structurally crusted soils by triggering termite activity through mulch was studied on three soil types in northern Burkina Faso, West Africa. A split-plot design was used in a fenced environment for the experiment. Insecticide (Dieldrin) was used at a rate of 500 g a.i. (active ingredient)/ha to create nontermite and termite plots. Three mulch types consisting of straw (Pennisetum pedicellatum), woody material (Pterocarpus lucens), and a composite mulch (straw and woody material) applied at a rate of 3, 6, and 4 tons/ha, respectively, were used to trigger termite activity. The grasses and woody species on the plots were surveyed. Nontermite plots responded weakly to mulch treatments, but even in the first year vegetation established on termite + mulch plots. Termite activity resulted in the increase of plant cover, plant species number, phytomass production, and rainfall use efficiency. Infiltrated water use efficiency and plant diversity were not statistically different among treatments during the first 2 years but were in the third. Woody species established only on termite plots. The three types of mulch plots showed greater vegetation development than bare plots, which remained bare throughout the experiment. Analysis of the termite and mulch interaction indicated that mulch plots without termites did not perform better than bare plots, especially in the case of woody plant regeneration. Vegetation rehabilitation was best with composite and straw mulches with termites, followed by woody mulch with termites; it was worst on bare plots.
A technique based on progressive fumigation was used to reduce soil microbial biodiversity, and the effects of such reductions upon the stability of key soil processes were measured. Mineral soil samples from a grassland were fumigated with chloroform for up to 24 h and then incubated for 5 months to allow recolonisation by surviving organisms. The diversity of cultivable and non-cultivable bacteria, protozoa and nematodes was progressively reduced by increasing fumigation times, as was the number of trophic groups, phyla within trophic groups, and taxa within phyla. Total microbial biomass was similar within fumigated soils, but lower than for unfumigated soil. There was no direct relationship between biodiversity and function. Some broad-scale functional parameters increased as biodiversity decreased, e.g. thymidine incorporation, growth on added nutrients, and the decomposition rate of plant residues. Other more specific parameters decreased as biodiversity decreased, e.g. nitrification, denitrification and methane oxidation. Thus specific functional parameters may be a more sensitive indicator of environmental change than general parameters. Although fumigation reduced soil microbial biodiversity, there was evidence to suggest that it selected for organisms with particular physiological characteristics. The consequences of this for interpreting biodiversity – function relationships are discussed. The stability of the resulting communities to perturbation was further examined by imposing a transient (brief heating to 40°C) or a persistent (addition of CuSO4) stress. Decomposition of grass residues was determined on three occasions after such perturbations. The soils clearly demonstrated resilience to the transient stress; decomposition rates were initially depressed by the stress and recovered over time. Resilience was reduced in the soils with decreasing biodiversity. Soils were not resilient to the persistent stress, there was no recovery in decomposition rate over time, but the soils with the highest biodiversity were more resistant to the stress than soils with impaired biodiversity. The study of functional stability under applied perturbation is a powerful means of examining the effects of biodiversity.
It is increasingly recognised that soil fauna have a significant role in soil processes affecting nutrient availability and crop performance. A field experiment was conducted in southern Burkina Faso (West Africa) to investigate the contribution of soil fauna to nutrient availability and crop performance after application of different organic materials with contrasting qualities. A split plot design with four replications was laid out. The main treatment was the use of insecticides, to establish plots without fauna next to plots with fauna. The sub-treatments consisted in the application of Andropogon straw, cattle dung, maize straw, compost or sheep dung and a control. Soil fauna significantly increased crop water use efficiency. Crop nutrient use efficiency was high with the use of easily decomposable organic material in the presence of soil fauna. Supplementing low quality organic resources with mineral nitrogen is required to optimise the effects of their interaction with soil fauna towards enhanced crop nutrient and water use efficiencies.
Functional stability, measured in terms of resistance and resilience of soil respiration rate and bacterial growth rate, was studied in soils from field plots that have been exposed to copper contamination and low pH for more than two decades. We tested whether functional stability follows patterns predicted by either the "low stress-high stability" or the "high stress-high stability" theory. Treatments consisting of soils with no or high copper load (0 or 750 kg/ha) and with low or neutral pH (4.0 or 6.1) were used. Stability was examined by applying an additional disturbance by heat (50 degrees C for 18 h) or drying-rewetting cycles. After heating, the respiration rate indicated that the soils without copper were less stable (more affected) than the soils with 750 kg/ha. Bacterial growth rate was more stable (resistant) to heat in the pH 6.1 than in the pH 4.0 soils. Growth rate was stimulated rather than inhibited by heating and was highly resilient in all soils. The respiration rate was less affected by drying-rewetting cycles in the pH 4.0 soils than in the pH 6.1 soils. Bacterial growth rate after drying-rewetting disturbance showed no distinct pattern of stability. We found that the stability of a particular process could vary significantly, depending on the kind of disturbance; therefore, neither of the two theories could adequately predict the response of the microbial community to disturbance.
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