Legume Cover Crops Research Articles

Using Legume-Enriched Cover Crops to Improve Grape Yield and Quality in Hillside Vineyards

Natural covering (NATC) has spread on hillside vineyards of central Italy as a replacement for tillage to reduce soil erosion, although it increased nitrogen and water needs. Therefore, in the current context of global warming, using cover crops (CCs) that require less water and provide nitrogen becomes crucial. The effects of two low-competition legume-enriched CCs in a rainfed hillside vineyard—a perennial legume–grass mixture (PLGM) and an annual legume cover crop of Trifolium alexandrinum (ALTA)—were compared with NATC over three years. PLGM and ALTA provided good levels of soil coverage, slightly lower than NATC, which had a negligible presence of legumes. PLGM and ALTA, due to low competition, enhanced vine vigor, resulting in thicker and wider canopies (as indicated by total leaf area and leaf layer number), higher pruning weight, and increased yield. PLGM and ALTA led to good qualitative levels, with higher grapes acidities, lower pH and total soluble solids content and, additionally, significantly higher yeast assimilable nitrogen content. In conclusion, implementing low-competition legume species in CCs is an effective tool to avoid soil erosion in a climate change scenario, leading to increased productivity, higher acidity, and improved nitrogen content in the grapes.

Reducing initial cotton yield penalties in a transition to conservation agriculture through legume cover crop cultivation – evidence from Northern Benin

Much effort has been spent on promoting conservation agriculture (CA) in Northern Benin to sustain the transition of cotton (Gossypium hirsutum L.) cropping systems toward agroecology. However, its limited adoption by farmers is often ascribed to initial yield penalties during the transition to CA and to trade-offs around crop biomass use. Here, we assess the effect of different CA-based cropping systems promoted in the region on water productivity and cotton yield in a three-year cotton/maize (Zea mays L.) crop rotation during the initial transition phase to CA. Three CA options were assessed combining different levels of soil disturbance and cover, and introducing cover crops to alleviate the biomass trade-offs. Direct seeding (DS), strip tillage (ST), and direct seeding mulched-based cropping systems (DMC) were compared with conventional tillage (CT) from 2017 to 2019 under a dominant soil type in the region, Haplic Lixisols. Two legume species, Stylosanthes guianensis (Aubl.) Sw. and Crotalaria retusa L. were grown as cover crops with maize under ST and DMC. The experiment followed a randomized block design comprising six replicates. After 2–3 years of DMC, the cotton yield advantage with respect to CT increased from 5 % to 7 %. Cotton yield penalties of respectively 11 % in 2018 and 26 % in 2019 were found for DS. ST treatment went from a yield advantage of 8 % in 2017 to a yield penalty of 20 % in 2019. The DMC and CT treatments gave similar and highest boll weights compared to the ST and DS treatments. The treatments had no significant difference regarding the number of bolls per plant. Soil water storage in the upper 30 cm depth and water use efficiency (WUE) were the highest in the plots with the DMC treatment compared to CT, ST, and DS. At 28 days of active vegetative stage (between 34 and 62 days after sowing), the WUE of seed cotton was 0.11 kg ha−1 mm−1 under DMC, while it was 0.08, 0.07, and 0.04 kg ha−1 mm−1 under DS, CT, and ST, respectively. The performance of DMC at increasing water productivity could be an argument to improve adoptability by farmers in northern Benin who are facing increased weather variability, given that the yield penalties often associated with early transitions to CA were not observed here with full DMC.

Enhancing Agroecology in Pepper (Piper nigrum L.) Cultivation with Centrosema pubescens Ground Cover: A Study from Central Bangka, Indonesia

<p>Pepper cultivation in Bangka Island primarily takes place on sandy land. Legume cover crops, such as <em>Centrosema pubescens</em>, which has been widely used as a ground cover, are anticipated to improve land quality by maintaining soil temperature and humidity, increasing soil organic carbon content, increasing soil porosity, and improving soil fertility. This research aims to analyze the agroecosystem of pepper plants, by comparing the use of the cover plant <em>C. pubescens</em> as a soil treatment and the absence of using these cover plants as a control. The research was conducted in farmers’ pepper gardens in Perlang Village, Central Bangka Regency, Bangka Belitung Province. The research employed a randomized block design, with <em>C. pubescens</em> and natural vegetation as treatments, each replicated 3 times. The variables measured were soil temperature and humidity; abundance of microorganisms; weed density, frequency, and dominance; chlorophyll a, chlorophyll b, and anthocyanin content of pepper leaves; photosynthesis rate; transpiration rate; stomatal conductance; soil chemical and physical properties. The results showed that <em>C. pubescens</em> as ground cover could reduce the dominance of the <em>Bidens pilosa</em> weed (relative dominance of 36.16%) but led to an increase in the dominance of <em>Chromolaena odorata</em> (relative dominance of 38.7%). <em>C</em>.<em> pubescens</em> ground cover could also maintain stable soil temperature and moisture, and increase P, K, Ca, and Mg soil content by 100%, 100%, 43.6%, and 48.3%, respectively. Furthermore, pepper plants grown with <em>C. pubescens</em> exhibited 25%, 23.7%, and 16% higher chlorophyll a, total chlorophyll, and carotenoid content, respectively, compared to those grown without the cover crop.</p>

Genetic and environmental drivers of legume cover crop performance: Hairy vetch

AbstractAmong 50 environments in the United States, we screened 35 hairy vetch (Vicia villosa Roth.) lines for traits of interest to cover cropping. We analyzed the influence of genotype, environment, and the genotype‐by‐environment interaction (G × E) on biomass, vigor, winter survival, emergence, flowering time, and nitrogen fixation. To explore how environments and G × E impacted each trait, we associated environment predictions and G × E loadings with weather and soil parameters. Environment had the largest influence on all traits, representing more than half of the variance. Environment predictions were significantly associated with weather and/or soil parameters for each trait. Biomass was associated with growing degree days, winter survival with freezing degree days without snow cover, growth stage with shortwave radiation, and emergence with soil texture. The G × E interaction was larger than genotypic variance for all traits except for winter survival and flowering time. The G × E interaction loadings were associated with soil sand content for biomass, air temperature for fall vigor and emergence, and snow cover for winter survival. Although it represented the smallest proportion of total variance, genetic effects were significant for all traits except for emergence, Ndfa, %N, and C:N. New hairy vetch breeding lines were superior to all commercially available lines for biomass and winter survival. Biomass harvest timing did not significantly change line rank, indicating that top‐performing lines can be used in diverse management systems. To select for high nitrogen contribution to subsequent crops, breeding programs can indirectly select for biomass rather than expensively evaluating symbiotic nitrogen fixation.

Long‐term tillage and cover cropping differentially influenced soil nitrous oxide emissions from cotton cropping system

AbstractClimate‐smart agricultural practices, such as no‐tillage (NT) and cover cropping, have been widely adopted and are anticipated to yield multiple benefits, including soil carbon sequestration, enhancing soil health, and crop yield stability. However, their influence on nitrous oxide (N2O) emissions varies, with the potential of both increasing and decreasing N2O emissions. Increasing N2O emissions under these practices may potentially offset the climate mitigation benefits from increased soil carbon sequestration. We investigated N2O emissions in response to 42 years of long‐term adoption of NT and legume cover crop, under nitrogen (N) rates of 0 and 67 kg N ha−1, in a continuous cotton system in the Southeastern United States. Intensive manual chamber‐based measurements were conducted over two growing seasons (2021–2022 and 2022–2023). Long‐term NT did not significantly affect cumulative N2O emissions during the study period (p > 0.05). Hairy vetch cover crop‐grown plots emitted two to three times more N2O than those without cover crops in 2021–2022, with no significant effect observed in 2022–2023. Cumulative emissions in cover crop plots were greater compared to those in no cover crop plots when fertilized with 67 kg N ha−1 in 2021–2022; however, this trend did not persist in 2022–2023. While interannual variability exists, our results generally suggest that long‐term NT may not increase N2O emissions, hence its adoption could enhance its broader soil health and climate benefits via soil carbon sequestration, whereas managing legume cover crop residues in N‐fertilized systems is critical to mitigate N2O emissions.

Cover crop quality and quantity influences organic corn performance more than soil context

AbstractCover cropping is a common practice among organic growers, well-known for its potential to supply nitrogen (N) to subsequent cash crops. Uncertainties and challenges exist in understanding how cover crops interact with soil properties and management practices across organic farms to supply N, and if such N supply is synchronous with subsequent cash crop N demand. An on-farm study examined cereal rye (Secale cereale) versus crimson clover (Trifolium incarnatum) planted before corn (Zea mays L.) in five organic farms in Michigan with a range of soil properties and management practices. High quality crimson clover residue [Carbon (C):N ratio 15:1] was associated with higher soil inorganic nitrogen, corn chlorophyll content, tissue N content, and grain yields relative to low quality cereal rye residue (C:N ratio 25:1). There were several lines of evidence that low quality cereal rye residue coupled with substantial biomass and a dry season limited N release during peak corn N demand. Nitrogen uptake efficiency (NUE, ratio of total N removed by corn to total N input) was above 1 for corn farms with low soil organic matter (SOM), active N and C pools, and lower than 1 for farms with high SOM and active N and C pools. Overall, cover crop biomass and cover crop quality was a more important driver of corn performance than background SOM content in organic corn farms. Our research highlights the challenges of ensuring sufficient N supply in organic field production, and the importance of planting a legume cover crop before corn.

Mitigating Carbon Emissions of Community Palm Plantations on Peatland

Increasing smallholder oil palm plantation activities on peatlands has become a challenge in achieving carbon emission reduction targets.The contradiction between the value of carbon emissions released and the carbon absorption capacity of oil palm plants needs to be known. This research the aim is to determine the value of lost emissions and the capacity to absorb carbon due to smallholder oil palm plantation activities on peatlands. So it can be a consideration in formulating carbon emission mitigation efforts in smallholder oil palm plantations on peatlands. The research was carried out descriptively using a spatial approach and field surveys on smallholder oil palm plantations on peatlands in Riau Province. Spatial analysis was carried out to determine the value of emissions lost due to changes in land cover. A field survey was carried out to measure absorption and emission values in several age classes of smallholder oil palm plantations. The research results found that carbon emissions from smallholder oil palm plantations on peatlands have increased every year along with the rate of additional opening of new plantations. The largest carbon emissions occur in the immature plant age class. As the age of oil palm plants increases, the value of peatland carbon emissions tends to decrease, while the value of carbon absorption increases. Mitigation to reduce carbon emissions that can be done is regulating the density of oil palm plants and implementing Legume Cover Crop on immature plants.

Professional networks and access to extension as drivers of sustainable agricultural practices among Ghanaian oil palm farmers

Increasing agricultural productivity through the uptake of sustainable agricultural practices (SAPs) offers a credible pathway to addressing food insecurity while preserving vital ecosystem resources, as such, factors that drive farmers' decisions to adopt these SAPs need examination. Most extant studies, on the adoption of SAPs, however, tend to place emphasis on socioeconomic incentives, giving little attention to the role of professional networks and institutional factors especially on oil palm which has strong links to deforestation and reduction in tree cover despite the numerous economic benefits. Using cross-sectional data from six oil palm producing regions in Ghana, this study analyses the role of producer membership, links with institutions such as NGOs, and extension access in the adoption of improved seeds, fertilizers, pest management practices, soil and moisture conservation practices, and legume cover crops among oil palm farmers in Ghana. The study employs a multivariate probit model to examine the probability of adopting SAPs and a poisson regression to model the intensity of SAPs adopted. The study also uses the instrumental variable approach to circumvent the issue of endogeneity. Results indicate that these networks and institutions significantly affect farmers’ adoption of SAPs. The study also finds heterogeneous associations with the adoption decisions depending on the type of innovation. In particular, we show evidence that farmers’ link with formal institutions is negatively associated with the adoption of diverse input intensive technologies, whereas it is positively associated with the adoption of natural resource management technologies. However, we find a consistent positive association of membership of producer organization on the adoption of different SAPs except legume cover cropping. Though differing relationships, we find that extension access and membership of producer organization are significantly associated with the intensity of SAPs adoption. Taken together, our findings suggest an integrated approach by the actors in the promotion of SAPs.

The Potential of Three Summer Legume Cover Crops to Suppress Weeds and Provide Ecosystem Services—A Review

Recently, there has been growing interest in the use of summer cover crops that can be grown during summer fallow periods of crop rotation. This study evaluates the potential of sunn hemp (Crotalaria juncea L.), velvetbean [Mucuna pruriens (L.) DC.] and cowpea [Vigna unguiculata (L.) Walp.]. as three annual legumes summer cover crops. The main objective of this review was to conduct global research comparing these summer cover crops to investigate the benefits, challenges, and trade-offs among ecosystems services when implementing these summer cover crops. In European agriculture, there are three main windows in crop rotation when these summer legumes can be grown: Around mid-spring after winter fallow, early summer after harvest of a winter crop, and mid- to late summer after harvest of an early-season crop. All three legumes can suppress weeds while they are actively growing. After termination, their mulch can create unfavorable conditions for weed emergence. Sunn hemp and velvetbean cover crops can cause a reduction in weed biomass of more than 50%. In addition to their ability to suppress weeds, sunn hemp, velvetbean, and cowpea provide a variety of ecosystem services, such as improving soil health, quality, and fertility, controlling pests, and sequestering carbon. The review highlights their promising role in weed suppression and their contribution to sustainable agricultural practices. However, further research is needed to evaluate their performance in weed management and their environmental impact in field trials under different soil-climatic conditions, as cover cropping is an effective practice but highly context-specific.

Comparison of the economic performance of organic and conventional corn–soybean–winter wheat rotations in southwestern Ontario, Canada

The economic viability of using summer-seeded legume cover crops (crimson clover, red clover, and hairy vetch) as a primary nitrogen (N) source for an organic corn ( Zea mays L.)–soybean ( Glycine max (L.) Merr.)–winter wheat ( Triticum aestivum L.) rotation was determined on a sandy loam soil in southwestern Ontario, Canada, by comparing gross profit for organic production (organic sources of N and phosphorus, no herbicides) to conventional production (no cover crops, synthetic fertilizers and herbicides added). Profits were determined for the initial 3-year transition period from conventional to organic production (2015–2017), and for 5 years of certified organic production (2018–2022). During the transition period when conventional crop prices applied to both production systems, organic production profits (CAD $1148–$1869 ha−1 per rotation) were lower than conventional profits (CAD $2126 ha−1 per rotation). During the certified organic period when price premiums were applied, organic soybean and corn profits (CAD $1995–$2274 ha−1 and $2819–$3195 ha−1 per year, respectively) were significantly greater than conventional soybean and corn profits (CAD $536 ha−1 and $1926 per ha−1, respectively). Winter wheat profits were slightly higher for organic production (CAD $426–$825 ha−1 per year) than for conventional production (CAD $371 ha−1 per year). During the certified organic production period, profits from the 3-year rotations were CAD $5533–$6153 ha−1 for organic production, and CAD $2860 ha−1 for conventional production. It was concluded that an organic rotation of corn–soybean–winter wheat/legume cover crop can be economically viable and more profitable than conventional production on sandy loam soil in southwestern Ontario.

Life Cycle Greenhouse Gas Emissions in Maize No-Till Agroecosystems in Southern Brazil Based on a Long-Term Experiment

Life Cycle Greenhouse Gas Emissions in Maize No-Till Agroecosystems in Southern Brazil Based on a Long-Term Experiment

Pooled DNA sequencing in hairy vetch (Vicia villosa Roth) reveals QTL for seed dormancy but not pod dehiscence.

Hairy vetch (Vicia villosa Roth) is a promising legume cover crop, but its use is limited by high rates of pod dehiscence and seed dormancy. We used phenotypically contrasting pooled DNA samples (n=24 with 29-74 individuals per sample) from an ongoing cover crop breeding program across four environments (site-year combinations: Maryland 2020, Maryland 2022, Wisconsin 2021, Wisconsin 2022) to find genetic associations and genomic prediction accuracies for pod dehiscence and seed dormancy. We also combined pooled DNA sample genetic association results with the results of a prior genome-wide association study. Genomic prediction resulted in positive predictive abilities for both traits between environments and with an independent dataset (0.34-0.50), but reduced predictive ability for DNA pools with divergent seed dormancy in the Maryland environments (0.07-0.15). The pooled DNA samples found six significant (false discovery rate q-value<0.01) quantitative trait loci (QTL) for seed dormancy and four significant QTL for pod dehiscence. Unfortunately, the minor alleles of the pod dehiscence QTL increased the rate of pod dehiscence and are not useful for marker-assisted selection. When combined with a prior association study, sixteen seed dormancy QTL and zero pod dehiscence QTL were significant. Combining the association studies did not increase the detection of useful QTL.

Steps toward developing legume cover crop varieties: Study of biomass and nitrogen partitioning and within‐plant δ115N variation of faba bean at different growth stages

AbstractModern legumes are engineered to enhance nutrient allocation to grains and maximize harvest index (HI) and yield. Breeding legumes for cover crop requires optimizing source‐sink relationship to prolong nutrient allocation to vegetative organs, support post‐flowering nodule activity, and extend biological nitrogen fixation (BNF). We studied the variation of faba bean (Vicia faba) germplasm for biomass (DM) and nitrogen (N) allocation to plant organs at the lower and upper parts of the canopy. Three genotypes were established during the 2019 and 2020 growing seasons, and DM, N, and δ15N of upper and lower leaves, stems, pods, seeds, and pod shells were quantified at vegetative, first‐pod, and full‐pod stages. Of the three genotypes, PI 678631 displayed early vigor, allocated more DM and N in vegetative organs, and accumulated more total DM and N than Windsor and PI 655333 by first‐pod stage. The advantage of PI 678631 over the other two genotypes seemed to be associated with smaller allocation of DM and N in pods at early reproductive phase. These findings support existing variations within faba bean germplasm that can be used to improve its ecosystem service as cover crop. Within‐plant variation of δ15N was minimal, suggesting that under favorable soil N and moisture where N remobilization is low, vegetative organs can serve as proxies to estimate the entire plant %Ndfa (proportion of plant N derived from the atmosphere) prior to plant maturity. The δ15N of plant organs at vegetative and early‐pod stages were similar and consistent with the only whole plant δ15N measurement in 2020.

Legume cover cropping and nitrogen fertilization influence soil prokaryotes and increase carbon content in dryland wheat systems

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.

Growth Test of Three Types of Legume Cover Crops Commonly Used in Oil Palm Plantation

Legume cover crops (LCC) in oil palm plantations aim to protect the soil from direct sunlight, suppress weed growth, suppress erosion, maintain soil moisture and increase soil fertility. Cover crops such as Mucuna bracteate (Mb), Pueraria javanica (Pj), and Calopogonium mucunoides (Cm) are commonly used in oil palm plantations. Nowadays, the superior cover crop seeds are limited. However, all of the cover crop seeds spread in the market are coming from unlicenced farms. As consequence, the seed quality and the purity are questioned. It is important to conduct research to identify the quality of those there LCC seeds. Germination methods used in the laboratory tests were the method of on paper (UDK), between-paper test (UAK), and soil media test. An experimental design completely randomized was used. The results showed that the germination percentage of Pj, Mb, dan Cm with the UDK method are 29%, 22%, and 4%; the UAK method are 33%, 41%, and 5%; meanwhile, the growth percentage of Pj, Mb, and Cm are 47%, 53%, and 7% respectively.

Quantifying soil carbon sequestration from regenerative agricultural practices in crops and vineyards

IntroductionRegenerative agriculture commonly aims to increase soil carbon sequestration, with potential benefits for human and ecosystem health, climate mitigation, and biodiversity. However, the effectiveness of various regenerative practices at increasing carbon sequestration is unclear.MethodsThis study identified and quantified the yearly soil carbon sequestration rate of regenerative practices in arable cropland and vineyard ecosystems through a literature review. We examined N=345 soil carbon sequestration measures across seven regenerative practices – agroforestry, cover cropping, legume cover cropping, animal integration, non-chemical fertilizer, non-chemical pest management, and no tillage.ResultsOur findings indicate that all seven practices effectively increased the carbon sequestration rate. There were no statistically significant differences among the practices. Combining these practices may further enhance soil carbon sequestration.DiscussionWe propose a sequence of regenerative practices that farmers can adopt, balancing ease of implementation and carbon sequestration effectiveness. To address under-studied practices, we recommend further research, including long-term monitoring studies and randomized controlled trials in perennial systems. Our recommendations aim to enhance the implementation and effectiveness of regenerative practices while mitigating the current challenge of limited sample sizes for quantifying carbon sequestration.

Pemberdayaan Masyarakat Melalui Bimbingan dan Pelatihan Pemanfaatan Legum Cover Crop Mucuna bracteata untuk Pengendalian Gulma dan Peningkatan Hara Tanah pada Perkebunan Kelapa Sawit

Weed control in oil palm plants is very necessary because it can cause losses both directly and indirectly. Kampar Polytechnic's partner in this PKM activity is the Pancuran Gading Village Office which is the Village Government that leads the implementation of Village development, development of Village community, and empowerment of Village communities, the majority of whom are oil palm farmers. So far, oil palm farmers prefer to use herbicides to control weeds. The impact of using herbicides is that it is not environmentally friendly and tends to increase maintenance costs because the price of herbicides is increasing every year. One solution that can be used is the use of the legume cover crop (LCC) Mucuna bracteata. Apart from functioning to suppress weed growth, LCC also plays a role in increasing soil fertility. With this community service activity, it is hoped that oil palm farmers will be able to cultivate Mucuna bracteata well in order to control weeds on oil palm plantations. In this way, dependence on herbicides can be reduced and oil palm maintenance costs can become more economical.

Productivity and LER (Land Equivalent Ratio) Napier grass-based intercropping with Legume Cover Crop (LCC)

Productivity and LER (Land Equivalent Ratio) Napier grass-based intercropping with Legume Cover Crop (LCC)

Can nitrogen in fall-planted legume cover crops be credited to maize?

Can nitrogen in fall-planted legume cover crops be credited to maize?

Legume cover crop as a primary nitrogen source in an organic crop rotation in Ontario, Canada: impacts on corn, soybean and winter wheat yields

This study presents results from the first 5 years of an organic cropping trial in Ontario, Canada, where legume cover crops were the primary nitrogen source in a soybean-winter wheat/cover crop-corn rotation. Treatments included cover crop termination using moldboard plow (MP) or chisel plow (CP), a no-cover crop control under conventional production (CK-C), and four cover crops including summer-seeded crimson clover (CC, Trifolium incarnatum L.), summer-seeded hairy vetch (HV, Vicia villosa L. Roth), summer-seeded red clover (RCss, Trifolium pratense L.), and frost-seeded red clover (RCfs). Summer-seeding occurred after wheat harvest (July–August), and frost-seeding occurred in early spring (March–April). At cover crop termination, average aboveground cover crop biomass ranged from 5.9 to 8.1 Mg ha−1, while accumulated biomass nitrogen ranged from 155 to 193 kg ha−1. Corn grain yields were 11.6 Mg ha−1 for MP and 10.2 Mg ha−1 for CP tillage-termination method; and 13.3 Mg ha−1 for CK-C, 10.9 Mg ha−1 for RCfs, 10.6 Mg ha−1 for HV, 10.2 Mg ha−1 for CC, and 9.5 Mg ha−1 for RCss. Organic winter wheat yields were nitrogen-limited, averaging 27% lower than CK-C. Winter wheat yields were 10–15% lower in the RCfs than in other summer-seeded cover crop treatments. Soybean yields were largely unaffected by the treatments. It was concluded that summer-seeded legume cover crops are an effective primary nitrogen source for corn, but not as effective for the winter wheat phase of the soybean-winter wheat-corn rotation.