Content uploaded by Ken Giller
Author content
All content in this area was uploaded by Ken Giller on Mar 04, 2014
Content may be subject to copyright.
A preview of the PDF is not available
Future benefits from biological nitrogen fixation: An ecological approach to agriculture
Abstract and Figures
Strategies for the enhancement and exploitation of biological nitrogen fixation are assessed with attention to the likely timescales for realization of benefits in agriculture. Benefits arising from breeding of legumes for N2-fixation and rhizobial strain selection have less potential to increase inputs of fixed N than alleviation of environmental stresses or changes in farming systems to include more legumes. Genetic engineering may result in substantial enhancement of N2-fixation, particularly if the ability to fix N2 is transferred to other crops but these are long-term goals. Immediate dramatic enhancements in inputs from N2-fixation are possible simply by implementation of existing technical knowledge. Apart from the unfortunate political and economic barriers to the use of agricultural inputs, better communication between researchers and farmers is required to ensure proper focus of research and development of appropriate technologies. Legumes must be considered within the context of the farming systems within which they are grown and not in isolation. Proper integration of legumes requires a good understanding of the role of the legume within the system and a better understanding of the relative contributions of N sources and of the fates of fixed N.
Figures - uploaded by Ken Giller
Author content
All figure content in this area was uploaded by Ken Giller
Content may be subject to copyright.
... Direct nitrogen transfer from the legume to the cereal crop during intercropping, which is most typically done with cereals, may enhance the nitrogen nutrition and nitrogen fixation of the partnered crop (Giller and Wilson, 1991) [7] . Moreover, the cropping approach makes use of legume intercrops since they reduce weed growth and soil erosion (Giller and Cadisch, 1995;Exner and Cruse, 1993) [8,5] . n chickpeas, weed infestation results in intense competition that can cut yields by up to 75%. ...
... Direct nitrogen transfer from the legume to the cereal crop during intercropping, which is most typically done with cereals, may enhance the nitrogen nutrition and nitrogen fixation of the partnered crop (Giller and Wilson, 1991) [7] . Moreover, the cropping approach makes use of legume intercrops since they reduce weed growth and soil erosion (Giller and Cadisch, 1995;Exner and Cruse, 1993) [8,5] . n chickpeas, weed infestation results in intense competition that can cut yields by up to 75%. ...
... Table 5 shows that the inoculation of seeds with CP17, CP41, and CP11 Rhizobium strains resulted in yield advantages of 25, 13.7, and 12.1%, respectively, over uninoculated seeds. The genotype of the legume, the Rhizobium strain, and their interactions with the biophysical environment and management techniques determine legume yields and nitrogen fixation (Giller et al., 1995). For this reason, it's critical to identify efficient Rhizobium strains that are compatible with the cultivar(s) and growing area(s). ...
The chickpea (Cicer arietinum L.) is a significant legume food crop in West Showa that farmers exploit to generate revenue and sustenance. Nevertheless, two major obstacles to production are the scarcity of high-quality seed and the poor fertility of the soil. Thus, the purpose of this study was to evaluate how Rhizobium inoculation affected yield, growth, and its constituent parts. Four Rhizobium strains (Cp11, Cp17, Cp41, and control) x four varieties (Eshete, Dimtu, Teketay, and Local) organized in factorial combinations were assessed using a randomized complete block design with three replications. All phenology and growth parameters, yield components, seed yield, and productivity indices were significantly influenced by both variety and Rhizobium strain, with the exception of crop phenology and hundred seed weight, which were not significantly influenced by Rhizobium strain. Plant height and the number of pods per plant were significantly impacted by the interaction between the R strain and variety. Four types yielded seed with a range of 2013.89 to 2777.78 kg ha-1, whereas inoculation procedures produced seed with a range of 2152.78 to 2690.97 kg ha-1. The Teketay variety and seeds infected with the Cp17 Rhizobium strain produced the best seed yield. Higher grain yield index per day, Rhizobium sensitive or infection index, yield index, and seed production efficiency were also seen in Teketay variety and seeds infected with Cp17 Rhizobium strain. The largest seed yield was produced by the Teketay variety inoculated with the Cp17 Rhizobium strain, and in most cases, the enhanced varieties' seeds inoculated with the Cp17 strain also produced high yields.
... For a scenario with soil limitations (lower boundary; table 1), spatially distributed values of potential N transfer were scaled to 20% in pixels that have soils with high or very high P immobilization potential according to [56] or a negative cropland P budget according to [57], which may substantially limit the establishment of a green manure [58]. We hence consider P limitation a general limiting factor that frequently also reflects suboptimal pH, aluminum toxicity, and other soil related limitations typically co-occurring in strongly weathered or otherwise degraded soils [59]. ...
Mineral nitrogen (N) fertilizer use is essential to maintain high-yielding cropping systems that presently provide food for nearly half of humanity. Simultaneously, it causes a range of detrimental impacts such as greenhouse gas emissions, eutrophication, and contamination of drinking water. There is growing recognition of the need to balance crop production with the impacts of fertilizer use. Here we provide a global assessment of the potential to reduce mineral fertilizer use through four interventions: capping surpluses, enhancing manure cycling to cropland, cultivation of off-season green manures, and cycling of human excreted N to cropland. We find that the combined potential of these interventions is a reduction in global N fertilizer use by 21-52%. The availability of interventions is spatially heterogeneous with most cropland having three to four interventions available with alternative N sources tending to be more abundant on cropland already receiving fertilizer. Our assessment highlights that these locally in part already practiced interventions bear great opportunities to mitigate synthetic N use and dependency globally. Yet, their limited adoption underpins the need for cross-sectoral policies to overcome barriers to their implementation and agronomic research on their robust scaling.
... Moreover, chickpea being a pulse crop required less amount of nitrogen due to legume-rhizobia association fix nitrogen in root nodules. However, it requires small amount of nitrogen during early stage of the crop for its establishment and growth until the onset of N-fixation (Giller and Cadisch, 1995). Thus, there is a need to apply nitrogenous fertilizer in the nitrogen deficient soils to overcome the deficiency of nitrogen and to harness higher yield of chickpea. ...
Nitrogen and weed control are the key to get maximum crop yield in most of the crops. In order to study the response of nitrogen levels and weed control practices on growth, productivity and economics of chickpea a field experiment was conducted during rabi season of 2019-20. The experiment consisting of twelve treatment combinations comprising two levels of nitrogen i.e. 15 and 30 kg/ha and six treatments of weed control practices viz., W1 : Weed free, W2 : Unweeded, W3 : Pendimethalin @ 0.75 kg/ha as PE, W4 : Imazethapyr @ 75 g/ha as PoE at 25 DAS, W5 : Pendimethalin @ 0.75 kg/ha as PE + IC at 30 DAS + HW at 45 DAS and W6 : Imazethapyr @ 75 g/ha as PoE at 25 DAS + HW at 45 days after sowing. The results obtained during the course of investigation indicated that significantly higher plant height at harvest, number of branches at harvest, number of pods per plant, grain yield and B:C ratio of chickpea were recorded with 30 kg nitrogen per hectare. Among the different weed control practices significantly tallest plant at harvest, number of pods per plant and grain yield were observed with weed free condition (W1) but it was at par with pendimethalin @ 0.75 kg/ha as PE + IC at 30 DAS + HW at 45 DAS (W5). Significantly the lowest plant height at harvest, number of pods per plant and grain yield were recorded by the application of imazethapyr @ 75 g/ha as PoE at 25 DAS (W4) due to phytotoxic effect of imazethapyr but number of pods per plant and grain yield were at par with unweeded treatment (W2). Whereas, the highest B:C ratio was obtained by treatment pendimethalin @ 0.75 kg/ha as PE + IC at 30 DAS + HW at 45 DAS (W5) which was closely followed by weed free treatment (W1).
... The chief benefit associated with mycorrhiza is its greater soil exploration and increasing uptake of P, N, K, Zn, Cu, S, Fe, Ca, Mg and Mn supply to the host roots (Habarte and Manjunath, 1987;Lu and Miller, 1989;Johnson et al, 1991;Kothari et al., 1991;Lambert and Weidensaul, 1991;Li et al., 1991;Champawat and Pathak, 1993;Marschner and Dell, 1994;Smith et al., 1994;Selvaraj and Subramaniyan, 1995;Abdul Malik, 2000). In addition to this, VA mycorrhizae portray other combining activities such as the control of root pathogens biologically, the biological nitrogen fixation, hormone production and greater ability to endure and resist water stress (Giller and Cadisch, 1995). ...
With an annual production of 490,000 tons, Nigeria is ranked the second-largest sesame producer in Africa and seventh globally. Mycorrhizae are consequently an essential component of tropical ecosystems, particularly in soils that are particularly deficient in some nutrients, such as nitrogen and phosphorus, as well as trace metals like copper and zinc. Inoculating arbuscular mycorrhizal fungi (AMF) into the soil has been demonstrated to be one of the biological methods by which the crop may tolerate stress and boost productivity. AMFs are particularly effective at stimulating plant growth. The effects of soil drought have been addressed in several ways, including reduced leaf chlorophyll content and disruptions in nutrient uptake. More focus has recently been placed on biological solutions, such as using microorganisms like mycorrhiza fungi. In arid and semiarid regions of the world, drought stress is one of the most significant abiotic stresses that negatively affects plant growth and development and their physiological and biochemical processes. As a result, numerous earlier investigations have noted that the chemical makeup of sesame seeds varies during drought stress. Therefore, the research aimed to assess how well AMF mitigated the negative effects of drought stress and enhanced the sesame's oil content, fatty acid profile, and non-enzymatic antioxidants.
... Thiessen-Martnes et al. (2005) su ovu osobinu pokrovnih useva nazvali "vrednost zamene đubriva". Mnogi naučnici (Bohlool et al., 1992, Peoples andCraswell, 1992;Giller and Cadisch, 1995) su mišljenja da je biološka fiksacija azota pomoću pokrovnih useva jedina alternativa mineralnim azotnim đubrivima u funkciji održavanja i povećanja proizvodnje hrane u budućnosti. Dinnes et al. (2002) preporučuju uvođenje pokrovnih useva u rotaciju kukuruza i soje kako bi se smanjio potencijal ispiranja NO3azota. ...
Cilj rada je ispitivanje uticaja pokrovnih useva, sa i bez primene
biofertilizatora (BF) na prinos zrna kukuruza kokičara (hibrid ZPSC 611k
FAO 600). Ogled je izveden u Institutu za kukuruz „Zemun Polje“ tokom
2014/2015. godine. Pokrovne useve (PU) su činile dve leguminoze: obična
grahorica i ozimi krmni grašak, dve neleguminozne vrste: ozimi ovas i
ozimi krmni kelj. Dve varijante sa smešama su obična grahorica + ozimi
ovas i ozimi krmni grašak + ozimi ovas i dve kontrole (kontrola I - slama i
kontrola II - golo zemljište). PU su sejani u jesen, zaoravani krajem aprila,
nakon čega je polovina parcele tretirana BF, dok je setva kukuruza
kokičara obavljena polovinom maja. Najveći prinos zrna je ostvaren na
varijantama: krmni grašak + ozimi ovas (5,34 t ha-1) i krmni kelj (4,89 t ha�1
) sa BF, dok je ozimi ovas ispoljio najmanji uticaj na prinos zrna kokičara.
Ključne reči: pokrovni usevi, biofertilizator, kukuruz kokičar, prinos
... Firstly, this is because only a small fraction (less than 30%) of the N in green manure and legume tree prunings is effectively recovered by the following cereal crop. Part of it can be leached, volatilized or immobilized by soil microorganisms (Giller and Cadisch, 1995). Secondly, high levels of N fixation can only be achieved if P is not limiting, and if appropriate inoculation is performed when the legume nodulates poorly. ...
Can farmers in sub-Saharan Africa (SSA) boost crop yields and improve food availability without using more mineral fertilizer? This question has been at the center of lively debates among the civil society, policy-makers, and in academic editorials. Proponents of the "yes" answer have put forward the "input reduction" principle of agroecology, i.e. by relying on agrobiodiversity, recycling and better efficiency, agroecological practices such as the use of legumes and manure can increase crop productivity without the need for more mineral fertilizer. We reviewed decades of scientific literature on nutrient balances in SSA, biological nitrogen fixation of tropical legumes, manure production and use in smallholder farming systems, and the environmental impact of mineral fertilizer. Our analyses show that more mineral fertilizer is needed in SSA for five reasons: (i) the starting point in SSA is that agricultural production is "agroecological" by default, that is, very low mineral fertilizer use, widespread mixed crop-livestock systems and large crop diversity including legumes, but leading to poor soil fertility as a result of widespread soil nutrient mining, (ii) the nitrogen needs of crops cannot be adequately met solely through biological nitrogen fixation by legumes and recycling of animal manure, (iii) other nutrients like phosphorus and potassium need to be replaced continuously, (iv) mineral fertilizers, if used appropriately , cause little harm to the environment, and (v) reducing the use of mineral fertilizers would hamper productivity gains and contribute indirectly to agricultural expansion and to deforestation. Yet, the agroecological principles directly related to soil fertility-recycling, efficiency, diversity-remain key in improving soil health and nutrient-use efficiency, and are critical to sustaining crop productivity in the long run. We argue for a nuanced position that acknowledges the critical need for more mineral fertilizers in SSA, in combination with the use of agroecological practices and adequate policy support.
El nitrógeno en el suelo es crucial para la agricultura, pero a menudo es limitante, afectando el rendimiento de los cultivos. La deficiencia requiere fertilizantes sintéticos, pero su uso inadecuado causa daños ambientales y costos elevados. Las bacterias del género Rhizobium, simbiontes de leguminosas, ofrecen una solución al fijar nitrógeno de manera sostenible, reduciendo la dependencia de fertilizantes. Esta investigación determinó el número más probable (NMP) de células de Rhizobium spp. procedente de dos biofertilizantes comerciales de origen ecuatoriano y mexicano en condiciones de invernadero. Para esto, se realizó la inoculación directa con disoluciones seriadas (10⁻¹ a 10⁻¹⁰) en macetas con pomina esterilizada al vapor, donde se germinaron plantas de frijol ejotero (Phaseolus vulgaris L.) de la variedad Blue Lake. A los 45 días después de siembra (DDS)
Publicación original: https://revistas.udec.cl/index.php/chjaas/article/view/10993
Typical of smallholder farming systems in sub-Saharan Africa, problems of low crop yields and declining soil fertility are widespread in Southern Africa, mainly due to the continued cultivation of crops with meagre nutrient inputs. In the face of growing food insecurity and the global food supply perturbations due to the COVID-19 pandemic and the Russia–Ukraine conflict, there is an urgent need to boost local food production, particularly by increased fertiliser use. While increased use of mineral fertilisers is critical for improved crop productivity, mineral fertilisers are on their own inadequate to sustainably increase crop yields due to multiple and complex biophysical and socio-economic constraints in smallholder farming systems in sub-Saharan Africa. The integrated soil fertility management (ISFM) framework provides a foundation for sustainable nutrient management focused on the integrated use of mineral fertilisers and organic resources in combination with improved crop varieties. In Southern Africa, fertiliser use is profitable and highly efficient on fertile fields, but less agronomically viable in lower fertility soils. There is evidence that integrating mineral fertilisers with organic nutrient resources is essential for increasing crop productivity and fertiliser use efficiency, particularly in the infertile soils. Mineral fertilisers and organic nutrient resources have different functions on soil fertility and crop production, and their use in combination can have synergistic effects. Organic resources play an essential role in restoring and maintaining soil fertility due to multiple benefits, including the supply of nutrients and increased soil pH and organic matter. Animal manures and crop residues have good potential for leveraging the benefits of increased fertiliser use in Southern Africa. Symbiotic biological nitrogen fixation provides an important option for supplying high-quality organic resources for improving soil nitrogen budgets and supplementing nitrogen derived from fertilisers. The main nitrogen fixation-based technologies with good potential to complement mineral fertiliser in Southern Africa include grain legumes with low nitrogen harvest indices and tree legumes. Combined with mineral fertiliser, these technologies can potentially improve productivity and fertiliser use efficiency by 10–60%, depending on soil fertility conditions and fertiliser application rates. As outlined in this chapter, most ISFM technologies have been developed and tested in field experiments. Achieving impact demands greater attention towards enhancing adoption by improving the targeting of ISFM technologies within heterogeneous smallholder farming systems, considering the availability of resources for crop production, input and output markets, and policy incentives.KeywordsIntegrated soil fertility managementSub-Saharan AfricaFertiliserMaize
Snake tomato is gaining popularity due to its nutritional, medicinal and health benefits. Its production is constrained by depleting soil fertility. Recently, there is increased interest in organic food owing to health and environmental benefits. Thus, an experiment on growth and yield of snake tomato as affected by fertilizer sources was conducted at Ponyan and Kabba during the 2019 cropping season. The experiment was laid out in a randomized complete block design with three replications. The treatments consisted of the control, residues from maize, guinea corn and spear grass, residues from soybean, cowpea and black bean, residues from cocoa and kola, pig manure, goat manure, cow dung manure and NPK plus B fertilizer. Data were taken on vine length, number of leaves, vine girth, days to 50% flowering, fruit length, fruit girth, number of seeds/fruit, fresh fruit weight, marketable fruits, non-marketable fruits and fruit yield (t/ha). Analysis of variance results indicated that plants treated with NPK plus B fertilizer significantly (P<0.05) recorded the longest vine, more number of leaves and branches. It also produced more fruits, longest fruit and heaviest fruits. Number of seeds/plant and marketable fruits were more in animal base manure. It is pertinent to know that non-marketable yield was highest in NPK plus B fertilizer. Contrarily, NPK plus B fertilizer increased yield, although statistically similar to animal base manure. Therefore, considering the benefits of organic manure on health and the environment, animal manure applied at 10 t/ha is recommended for snake tomato production in the study area
The soil, nutrient and water conservation is the main problem faced by farmers and investigators under the corn crop-based systems in Central America and Mexico. Several farmers from Honduras have come up with an efficient technology for the corn planted on hills, in which the bean manure is planted in rotation with corn during the dry season. The results from the conducted survey, at the Departamento de Atlantida in Honduras, indicate that 66 % of the farmers grow most of the corn through the protective mat produced by the beans during the rainy season. Among the advantages of this rotation, compared to the traditional burned and cleared land, are the higher yields with les ser dependency of external imputs, shorter rest periods, lower land preparation costs, less soil erosion and lower risk of drought damages. The problems linked to the diffusion ofthe system include the risk ofland slides and a higher plague's incidence (rats) on the corn planted through the manure mat. Usually, the amount of land available in the regionalland markets is the determining factor on the diffusion of this system, and not the size of the farm nor the form of land tenancy.
This work provides information relevant to the nitrogen (N) management strategy of multiple cropping in upland systems in the humid tropics of the transmigration areas of Sumatra, Indonesia. The experiment was conducted on a red yellow podzolic (orthoxic palehumult) soil at Kota Bumi in Lampung Province, Indonesia, where the annual rainfall of 2430 mm allows three consecutive crops per year to be grown. Two sequential systems were studied—rice-soybean-cowpea and rice-corn-cowpea. For each crop, crop residues and fertilizer applied to subplots were labelled with 15N so that the crop N uptake for the planted crop and subsequent crops could be partitioned into that derived from N fixation (legume only), fertilizer, crop residues and soil. The experiment was conducted over two years (6 crops). The percentage of soybean and cowpea N derived from N fixation was 33% for soybean and 12–33% for cowpea. Removal of N in seed exceeded the amount derived from fixation. Efficiency of utilization of fertilizer N ranged from 9–18% of that applied for wet season upland rice (900–1300 mm rainfall) to 32–40% for dry season corn (410–840 mm rainfall). Residual fertilizer N recovery by subsequent erops was as high as 14% of that applied to corn and as low as 2% of that applied to rice. Legume residues were an effective source of N to the following crop, particularly cowpea residues applied to rice, where percent recovery was higher than from fertilizer. Cereal residues were of lower value as a source of N. Percent utilization of N in crop residues by the following crop was related to the % N in the residues and the rainfall received by the following crop (R2=0.69, P=0.01).
A fundamental shift has taken place in agricultural research and world food production. In the past, the principal driving force was to increase the yield potential of food crops and to maximize productivity. Today, the drive for productivity is increasingly combined with a desire for sustainability. For farming systems to remain productive, and to be sustainable in the long-term, it will be necessary to replenish the reserves of nutrients which are removed or lost from the soil. In the case of nitrogen (N), inputs into agricultural systems may be in the form of N-fertilizer, or be derived from atmospheric N2 via biological N2 fixation (BNF).
Although BNF has long been a component of many farming systems throughout the world, its importance as a primary source of N for agriculture has diminished in recent decades as increasing amounts of fertilizer-N are used for the production of food and cash crops. However, international emphasis on environmentally sustainable development with the use of renewable resources is likely to focus attention on the potential role of BNF in supplying N for agriculture. This paper documents inputs of N via symbiotic N2 fixation measured in experimental plots and in farmers’ fields in tropical and temperate regions. It considers contributions of fixed N from legumes (crop, pasture, green manures and trees), Casuarina, and Azolla, and compares the relative utilization of N derived from these sources with fertilizer N.
The response of plant dry matter to addition of a low grade Brazillian (Patos) phosphate rock was increased by mycorrhizal inoculation (strain E3) of Stylosanthes guianensis and Desmodium intortum, but less so by inoculation of Cenchrus ciliaris and Paspalum plicatulum. The effect was related partly to the extent of root development. In the presence of a nitrification inhibitor the utilisation of Potos rock phosphate by Paspalum was higher with NH4+-N than with NO3-N. This effect was attributed to acidification which in turn was related to the organic anion content of the plants. The results indicate the potential for improving the utilization of the low grade phosphate rock on an acid oxisol by mycorrhizal inoculation of herbage legumes and by soil acidification when growing grasses.
The purpose of this chapter is to bring together examples of low-input soil management technology adapted to well-drained, acid, inherently infertile soils of the American tropics classified mainly as Oxisols and Ultisols. Soil taxonomy terminology, including soil moisture regimes, is used. The outcome of the race between world food production and population is determined in the tropics, where most of the world's undernourished people live. The applicability of high-input soil management technologies, however, diminishes in marginal lands where soil and water constraints are not easily overcome at low cost. The rising price spiral of petroleum-related products since has limited the economic feasibility of soil management technologies based on the intensive use of purchased inputs, particularly for farmers with limited resources in the tropics. The term ‘‘low’’ is used in relation to “high”-input technology where the application of fertilizers and amendments largely eliminate chemical soil constraints. The identification of plant species and ecotypes tolerant to the main acid soil stresses allows the development of low-input soil management systems for Oxisol and Ultisol regions where socioeconomic constraints prevent the widespread application of large quantities of lime and fertilizers. The basic approach is to use plants adapted to acid soil constraints, to maximize the use of fertilizers and lime needed to produce about 80% of their maximum yield, and to take advantage of favorable attributes of acid, infertile Oxisols and Ultisols.