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Above-ground broadleaf weed species (a) diversity, (b) evenness and (c) richness based on the Shannon diversity index in CR, DIR, OAM and OGM treatments in 2008. Bars represent the standard error of the mean. Letters above the bars represent differences between treatments (P < 0.05).
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While weed management is consistently a top priority among farmers, there is also growing concern for the conservation of biodiversity. Maintaining diverse weed communities below bioeconomic thresholds may provide ecosystem services for the crop and the surrounding ecosystem. This study was conducted to determine if weed diversity, density and biom...
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Context 1
... above-ground broadleaf weed diversity was only measured in 2008 and was lower than the weed seedbank species diversity, ranging from 0.34 to 0.78. The above- ground broadleaf weed diversity (H 0 ) was greatest in the OGM treatment in 2008, but the diversity did not differ among the remaining treatments (Fig. 3a). Weed species evenness (J) did not differ between the OGM and CR treatments, but evenness was greater in the OGM treatment compared to the DIR and OAM treatments (Fig. 3b). Weed species richness (S) of the OGM treatment was greater than the CR and DIR treatments, but not the OAM treatment. Richness of the OAM treatment was greater than ...
Context 2
... from 0.34 to 0.78. The above- ground broadleaf weed diversity (H 0 ) was greatest in the OGM treatment in 2008, but the diversity did not differ among the remaining treatments (Fig. 3a). Weed species evenness (J) did not differ between the OGM and CR treatments, but evenness was greater in the OGM treatment compared to the DIR and OAM treatments (Fig. 3b). Weed species richness (S) of the OGM treatment was greater than the CR and DIR treatments, but not the OAM treatment. Richness of the OAM treatment was greater than the CR treatment, but not the DIR treatment. There was no difference in the weed species richness between the con- ventional treatments (Fig. 3c). Across all sampling ...
Context 3
... to the DIR and OAM treatments (Fig. 3b). Weed species richness (S) of the OGM treatment was greater than the CR and DIR treatments, but not the OAM treatment. Richness of the OAM treatment was greater than the CR treatment, but not the DIR treatment. There was no difference in the weed species richness between the con- ventional treatments (Fig. 3c). Across all sampling methods, weed species diversity was generally greatest in the OGM treatment. Weed seedbank diversity was greatest in the OGM treatment in 2007 using the elutriation method and in 2008 when measuring the above-ground broadleaf diversity. The OGM treatment shared the greatest diversity with the CR treatment using the ...
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Understanding the composition of seed banks in pasture soils would help farmers anticipate and manage for weed problems. We characterized the soil seed bank in eight pastures and hayfields [two alfalfa (Medicago sativa L.) and two predominantly grass hayfields; two recently established and two permanent pastures] within an organic dairy farm in sou...
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... During the latest two surveys, the development of production systems and cropping methods have been twofold regarding weed flora. Increase in the area of organic cropping has extensified production, leading to promotion of weed flora, both in terms of diversity and abundance (Rydberg and Milberg 2000, Hyvönen et al. 2003, Romero et al. 2008, Wortman et al. 2010. The area of organic production (incl. ...
Regular weed surveys provide information on changes in weed communities. The composition of weed flora in spring cereal fields was investigated in southern and central Finland during 2020–2022. The survey was conducted in 16 regions, 226 farms and 549 fields. The occurrence of weeds was assessed in the second half of July from 90 organically cropped and 459 conventionally cropped fields. The weed flora was dominated by broad-leaved species, representing 81% of the total number of 138 identified species. The average species number per field was 21 in organic fields and 12 in conventional fields. The most frequent weed species in organic fields were Chenopodium album 99%, Erysimum cheiranthoides 84%, Viola arvensis 83% and Stellaria media 82%. In conventionally cropped fields, the most frequent species were Viola arvensis 83%, Stellaria media 65%, Galeopsis spp. 59% and Galium spurium 59%. The two most common grass species in both production systems were Poa annua and Elymus repens. The frequency and density of Poa annua had increased substantially in conventional cropping since the previous survey in 2007–2009. The average density of weeds was 384 plants m-2 in organic fields and 147 plants m-2 in sprayed conventional fields. The average air-dry biomass of weeds was 678 kg ha-1 and 151 kg ha-1, respectively. Elymus repens produced almost a quarter of the total weed biomass in both production systems. Changes in weed flora were minor in terms of frequency and density of the most common broad-leaved weed species. Increased infestation of Poa annua in conventional cropping calls for special attention. The dominance of Elymus repens decreased in both production systems since the previous survey.
... 2020) has partly triggered a counter process by enhancing floristic diversity (Stein-Bachinger , 2020). This was also detected in other regions, for example, by Norton et al. (2006), Wang et al. (2007);Wortman et al. (2010) and Rahmann (2011). ...
In the past, the floristic diversity of arable fields has been described in terms of species diversity (SD) and their degree of coverage (C), but never in combination with the recording of the actually flowered species (FS) and their flowering intensity (FI) to striking differences in the cultivation methods on arable land. In relation to SD and C, however, FS and FI may provide important additional information on the functional biodiversity of fields. The aim was therefore to investigate the effects of (a) conventional, (b) organic, and (c) smallholder (never application of herbicides) on the floristic diversity. Using a region in Germany, we investigated SD, C, FS, and FI synchronously in (a), (b), and (c), by 356 vegetation surveys (5 × 5 m plots) conducted in spring and summer in 2019 in winter cereals. Statistical tests were used to analyze the differences between (a), (b), and (c). The medians were used to compare the floristic diversity of (a), (b), and (c) and finally relationships of FS and FI to SD were analyzed in relation to the cultivation methods. Significant differences in SD, C, FS, and FI were found between the (a), (b), and (c) in spring and summer characterized by sharp declines from (c) to (b) to (a). A drastic reduction in floristic diversity from (c) 100 to (b) 52 to (a) 3 was determined. Plants in flower (FS, FI) were very poorly in (a), moderately well to well in (b), and well to very well represented in (c). (C) to (a) was characterized by a sharp decline and from (a) to (b) by sharp increase in floristic diversity. With current acreage proportions of (a) in mind, this would affect, about one third of land area in Germany, associated with a drastic reduction in functional biodiversity for insects.
... Perennial legume-grass mixtures strongly decrease the risk of annual summer weeds and also reduce annual winter weeds, especially if grown for three years [109]. The dense vegetation structure and the repeated cutting weaken the vegetative organs of the competing weed plants [48], decreasing the broadleaf (and not grass) weed seed bank and increasing weed diversity [110]. ...
This review analyzes the potential role and long-term effects of field perennial polycultures (mixtures) in agricultural systems, with the aim of reducing the trade-offs between provisioning and regulating ecosystem services. First, crop rotations are identified as a suitable tool for the assessment of the long-term effects of perennial polycultures on ecosystem services, which are not visible at the single-crop level. Second, the ability of perennial polycultures to support ecosystem services when used in crop rotations is quantified through eight agricultural ecosystem services. Legume-grass mixtures and wildflower mixtures are used as examples of perennial polycultures, and compared with silage maize as a typical crop for biomass production. Perennial polycultures enhance soil fertility, soil protection, climate regulation, pollination, pest and weed control, and landscape aesthetics compared with maize. They also score lower for biomass production compared with maize, which confirms the trade-off between provisioning and regulating ecosystem services. However, the additional positive factors provided by perennial polycultures, such as reduced costs for mineral fertilizer, pesticides, and soil tillage, and a significant preceding crop effect that increases the yields of subsequent crops, should be taken into account. However, a full assessment of agricultural ecosystem services requires a more holistic analysis that is beyond the capabilities of current frameworks.
... The global objective of this research is to assess how spatial remote sensing may support the organic crop certification process by developing a method that would enable certification bodies to target for priority in situ control crop fields declared as organic but that show an appearance on satellite imagery closer to conventional fields. For this purpose, the ability of multispectral satellite images to discriminate between organic and conventional maize fields was assessed through the use of a set of satellite images of different spatial and spectral resolutions acquired at different crop growth stages over a large number of maize fields (32) being part of an operational farm in Germany. In support to this main objective, a set of in situ measurements was conducted to characterize the nature of the biochemical and biophysical differences between organic and conventional maize fields. ...
... This tendency in Germany was reinforced by the fact that organic farms are often located in less favorable environments [30]. Studies comparing the weed abundance in organic and conventional maize fields systematically show higher weed abundance in organic fields compared to conventional ones [31][32][33][34]. This lower weed abundance in organic crops (not only maize) is explained by the use of herbicides in conventional fields and also by the generally lower crop density in organic fields that allows weeds to develop more abundantly [35,36], personal communication of Doreen Gabriel, Institut für Pflanzenbau und Bodenkunde, Julius Kühn-Institut, Bundesforschungsinstitut für Kulturpflanzen, Germany, 2017]. ...
The annual certification of organic agriculture products includes an in situ inspection of the fields declared organic. This inspection is more difficult, time-consuming, and costly for large farms or in production regions located in remote areas. The global objective of this research is to assess how spatial remote sensing may support the organic crop certification process by developing a method that would enable certification bodies to target for priority in situ control crop fields declared as organic but that would show on satellite imagery an appearance closer to conventional fields. For this purpose, the ability of multispectral satellite images to discriminate between organic and conventional maize fields was assessed through the use of a set of four satellite images of different spatial and spectral resolutions acquired at different crop growth stages over a large number of maize fields (32) that are part of an operational farm in Germany. In support of this main objective, a set of in situ measurements (leaf hyperspectral reflectance, chlorophyll, and nitrogen content and dry matter percentage, crop canopy cover, height, wet biomass and dry matter percentage, soil chemical composition) was conducted to characterize the nature of the biochemical and biophysical differences between organic and conventional maize fields. The results of this research showed that highly significant biochemical and biophysical differences between a large number of organic and conventional maize fields may exist at identified crop growth stages and that these differences may be sufficiently pronounced to enable the complete discrimination between crop management modes using satellite images issued from quite common multispectral satellite sensors through the use of spectral or spatial heterogeneity indices. These results are very encouraging and suggest, for the first time, that satellite images could effectively support the organic maize certification process.
... Shannon's diversity index in conventional farms was also positively correlated with percentage of fields in farms that were covered with vegetation during wintertime (share of "green fields"). A literature study shows that conventional farms that cultivated aftercrops as green manure can have an increased Shannon diversity index of weeds [52,53]. Armengot et al. (2013) [27] found that mechanical weed management had no negative effect on the biodiversity of weeds. ...
In recent years, the European Union has been paying particular attention to the problem of biodiversity loss. The possibilities of its assessment and conservation are included in the latest European Union (EU) policies and reflected in the European Biodiversity Strategy. The biodiversity of weeds in winter cereals in organic and conventional low-input farms in Eastern Poland was investigated during a 3-year period. Significantly more species and larger abundance were found in organic than in conventional farming systems. The biodiversity of these communities was described by Shannon’s diversity and Simpson’s dominance indices, which showed diversity to be well maintained in both farming systems; however, significantly higher Shannon’s index and significantly lower Simpson’s index values were observed in organic farms. Both farming systems were the mainstay of endangered and rare species, as well as some invasive weed species. Weed communities of organic farms were dominated mostly by Setaria pumila and Elymus repens, while conventional farms were dominated by Juncus bufonius and Setaria pumila. The study showed the importance of organic farming systems for biodiversity conservation. It was also shown that low-input (traditional) conventional farms are also beneficial for biodiversity conservation.
... There were greater numbers of water-stable aggregates in organic, alfalfa-based systems than grain-based systems (Jokela et al. 2011;Williams et al. 2017), and while there was no difference in water storage between the two organic systems, they were both higher than conventional counterparts (Williams et al. 2017). Higher weed diversity and larger weed seedbank was also observed in the alfalfa-based systems when compared with grain-based systems (Wortman et al. 2010). Finally, alfalfa-based systems may be more economically and agronomically viable than grain-based systems (Smolik et al. 1995;Welsh et al. 2009). ...
Soil health is an old concept receiving renewed attention. Defined as a soil’s capacity to function, soil health is composed of physical, chemical, and biological attributes. The improvement and maintenance of soil health is considered a cornerstone of organic agriculture. Although there are numerous studies that compare organic systems with conventional systems, fewer studies compare organic systems with each other to determine how best to improve soil health metrics. In this review, we focused on nine indicators of soil health (aggregate stability, water holding capacity, infiltration/porosity, erosion/runoff, nutrient cycling, organic carbon, microbial biomass, macrofauna abundance, and weed seed bank). We found 153 peer-reviewed, published studies that measured these soil health indicators in two or more organic treatments. Overall, published research focused on four key practices: (1) cover crops, (2) organic amendments, (3) rotation diversity and length, and (4) tillage. Of these, 26 studies focused on cover crops, 77 on organic amendments, 32 on crop rotations, 40 on tillage, and 22 included more than one practice. Eighty percent of the studies were conducted in the USA and Europe. We found strong agreement in the literature that roll-killed cover crops suppressed weeds better than disking and that weed suppression required high levels of cover crop biomass. Combinations of organic amendments such as composts, manures, and vermicomposts improved soil health metrics compared to when applied alone. Including a perennial crop, like alfalfa, consistently improved soil carbon (C), nitrogen (N), and aggregate stability. Soil health metrics were improved under shallow, non-inversion tillage strategies compared with conventional tillage. Despite their importance for climate change mitigation and adaptation, the effect of practices on aggregate stability and water dynamics were under-studied compared with other soil health metrics. There is a great deal of variety and nuance to organic systems, and future research should focus on how to optimize practices within organic systems to improve and maintain soil health.
... Results of our study are consistent with the findings of Komatsuzaki and Wagger (2015), who observed reduced biomass tissue N in weedy compared to cover crop plots. Long-term organic farm management can contribute to greater weed abundance (Wortman et al. 2010) and resulting N recovery by weeds (Wortman 2016). Nonetheless, planted cover crops in this study provisioned 28-33% more biomass tissue N than fallow weeds. ...
Cover crops can supply and recycle soil nitrogen (N) in agroecosystems. With increasing interest in cover crop mixtures, farmers have questions about how N cycling is affected by individual species when planted alone or in mixtures. Field trials were conducted on two organic vegetable farms during the spring and summer of 2014–2016 to quantify biomass tissue N provisioned, soil nitrate (NO3-N) scavenged, and soil NO3-N mineralized from 12 species of cover crops (six spring and six summer species) planted in monoculture or five-way mixtures. All cover crops were compared to weedy and weeded (no cover crops or weeds) controls. Cover crops provisioned 28–33% more biomass tissue N than fallow weeds. Among spring cover crops, field pea produced the most biomass tissue N (131 ± 13 kg N ha⁻¹; mean ± 1 SE) but that benefit disappeared when pea abundance was reduced in mixtures. Soil NO3-N to a depth of 0.2 m was reduced by 50–67% during cover crop and weed growth, regardless of treatment. Soil NO3-N availability approximately 1 month after incorporation of cover crop and weedy residues varied by treatment. Post-incorporation soil NO3-N was 17–19% greater in pea and soybean monocultures compared to mixtures; conversely, soil NO3-N was 17–19% lower following incorporation of buckwheat and sudangrass monocultures compared to mixtures. Results of this study demonstrate that cover crop N recycling services in near-surface soil are largely independent of species or mixture, but N provisioning services require careful management and species selection to ensure maximum biomass tissue N and timely N mineralization.
... Moreover, a variety of weeds can restrict the invasion of a single weed. Suitable weed cover can also reduce soil erosion and improve soil chemical properties (Wortman et al., 2010). ...
The long-term use of herbicides to remove weeds in fallow croplands can impair soil biodiversity, affect the quality of agricultural products, and threaten human health. Consequently, the identification of methods that can effectively limit the weed seed bank and maintain fallow soil fertility without causing soil pollution for the next planting is a critical task. In this study, four weeding treatments were established based on different degrees of disturbance to the topsoil: natural fallow (N), physical clearance (C), deep tillage (D), and sprayed herbicide (H). The changes in the soil weed seed banks, soil nutrients, and soil microbial biomass were carefully investigated. During the fallow period, the C treatment decreased the annual and biennial weed seed bank by 34% against pretreatment, whereas the H treatment did not effectively reduce the weed seed bank. The D treatment had positive effects on the soil fertility, increasing the available nitrogen 108% over that found in the N soil. In addition, a pre-winter deep tillage interfered with the rhizome propagation of perennial weeds. The total biomass of soil bacterial, fungal, and actinomycete in H treatment was the lowest among the four treatments. The biomass of arbuscular mycorrhizal fungi in the N treatment was respectively 42%, 35%, and 91%, higher than that in the C, D, and H treatments. An ecological weeding strategy was proposed based on our findings, which called for exhausting seed banks, blocking seed transmission, and taking advantage of natural opportunities to prevent weed growth for fallow lands. This study could provide a theoretical basis for weed management in fallow fields and organic farming systems.
... Typically, weeds are more abundant and weed communities are more diverse in organic cropping systems compared with conventional cropping systems, where synthetic herbicides are used (Hole et al. 2005;Kremen and Miles 2012;Menalled et al. 2001;Ryan et al. 2010b;Wortman et al. 2010). The agroecological consequences of increased weed species diversity are not well understood. ...
Weed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [ Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (i) High Fertility (HF), (ii) Low Fertility (LF), (iii) Enhanced Weed Management (EWM), and (iv) Reduced Tillage (RT). In addition, we created Weed Free sub-plots within each system in order to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in Weed Free sub-plots was 10% greater than soybean yield in the Ambient Weed sub-plots that received standard management practices of the system in which they were located. Although weed competition limited soybean yield across all systems, the EWM system which had the lowest weed density also had the lowest soybean yield. Future research should aim to overcome such tradeoffs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.
... The reason behind that is the fact that soil seed bank is closely related to actual weed infestation. The scattering of seeds from the same phytocoenosis is the main source of their inflow to the soil (Murphy et al., 2006;Wortman et al., 2010). Since the weed infestation in 2013 was high (even in the conventional farming system), and soil samples were collected in June and July, most of weed species were able to produce seeds and deposit them in the soil seed bank. ...
