Cover Crop Species Research Articles

Effect of cover crop species and termination timing on corn growth and seedling disease

AbstractLater spring termination of fall‐planted cover crops can result in more biomass production, which has the potential to improve environmental benefits. However, later cover crop termination can also have the potential to harm cash crops, such as through increases in corn seedling disease. With the objective of better understanding such potential competing interactions, we evaluated the impact of early and late termination timing of two cover crops—cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth.)—on growth, seedling disease, and grain yield of corn in 2021 and 2022 in Nebraska. The total biomass production varied among treatments. Hairy vetch biomass was lower than cereal rye biomass at both termination times in 2021, but not different from cereal rye terminated early in 2022. Radicle root rot severity, a symptom of corn seedling disease, was not affected by cover crops in 2021. In 2022, however, radicle root rot was most severe in cereal rye terminated late treatments. Hairy vetch did not affect radicle root rot severity, regardless of termination time. Late termination of cereal rye resulted in a reduction in corn yield of 15.3% in 2021 and 76.1% in 2022 compared to no cover crop. Corn (Zea mays L.) grain yield was not affected following hairy vetch at either termination timing. Our results suggest that corn planted following late‐terminated cereal rye can increase the severity of root rot and decrease corn grain yield; however, planting green into hairy vetch can be a successful option to increase biomass without increasing corn seedling disease or decreasing corn yield.

Assessing the long‐term effects of conservation agriculture on cotton production in Northeast Louisiana using the denitrification–decomposition model

AbstractConservation agriculture (CA) aims to sustain agricultural production, soil, and environmental health in agroecosystems and has been promoted throughout the United States. The adoption of CA in cotton (Gossypium hirsutum) systems provides both agronomic and environmental benefits. Yet, there is limited information on the long‐term effects of CA practices on crop yield and adaptation strategies. An integrated CA system, that is, cover crops with no‐tillage (NT) instead of conventional agriculture, was implemented in the long‐term field experiments and assessed with an integrated biogeochemical model. Using the denitrification–decomposition model, this study estimated the effects of four different cover crops, for example, native grass (NG), hairy vetch (Vicia villosa), winter wheat (Triticum aestivum L.), and crimson clover (Trifolium incarnatum), on cotton yield under four different nitrogen (N) levels (e.g., 0, 50, 100, and 150 kg N/ha) and estimated responses on carbon (C) sequestration, and ecosystem functionality over a 10‐year study. The NT‐NG 50 N was used as a calibration dataset to accurately estimate the cotton lint yield with a normalized root mean square error (NRMSE) of 21% and model efficiency of 0.3. The calibration data validated the effects of hairy vetch, winter wheat, and crimson clover under the NT‐50 N with NRMSE of 24%, 21%, and 25%, respectively. According to the scenario analysis, the 50 kg N/ha application with a single‐irrigation event (10‐cm depth) was most beneficial for maximizing the cotton yield with cover crop incorporation at the NT system over the long term. The effects of increasing cover crop biomass (i.e., double seed rate) on C content, regardless of N application rates, varied based on the relationship between the main and cover crop species. Besides, the furrow plow tillage system provided efficient C sequestration. The proposed approach stands to provide agricultural and environmental sustainability with the implementation of cover crop or crop residue incorporation instead of increased N application, seed rates, and irrigation events under NT practices.

Evaluation of single and mixed cover crops species in a sandy loam soil under corn production

AbstractInformed selection of cover crop species is critical for optimizing their benefits by considering the costs of adoption and potential initial negative impact on yields against the proven benefits for sustainable production. The Lower Mississippi Delta region is lagging in cover crop adoption, partly due to a paucity of this information from the area, despite being one of the major row crop‐producing regions in the United States. Common cover crop species in the region, cereal rye (CR) (Secale cereale), hairy vetch (HV) (Vicia villosa), and crimson clover (CC) (Trifolium incarnatum), and their possible two‐ and three‐combination mixes were evaluated for their impact on biomass production, enzyme activities, nutrient cycling, and corn (Zea mays) yields. HV + CC + CR and HV + CR produced the highest biomass and lowest yields compared to all treatments. HV and CC produced the least biomass but comparable yields to no cover crop. HV + CC + CR, HV + CR, CR, CC, and HV treatments had comparable total nitrogen, phosphorus, and soil organic carbon levels in the surface 0‐ to 5‐cm depth. Generally, CC alone and the HV + CR mix consistently displayed significantly higher phosphatase, N‐acetylglucosaminidase, β‐glucosidase, and cellobiohydrolase activities compared to all other treatments, while CR had the lowest. The single species of CC or HV may be the best option in the short term for initial cover crop implementation, rotating with CR a few years down the line for optimum long‐term benefits under corn production in this region.

Effects of Fall and Winter Cover Crops on Weed Suppression in the United States: A Meta-Analysis

Cover cropping recently emerged as a promising alternative to conventional tillage and herbicide use for weed suppression in agricultural systems. We investigated their effectiveness in weed control and the varying effects of different management strategies using a meta-analysis. Our analysis studied two categories: weed biomass control and weed density control. We employed a random-effect model to analyze weed biomass to address between-study heterogeneity and found that cover crop treatments led to a significant 62.6% reduction in weed biomass. These results are robust to outliers and publication bias. Furthermore, subgroup analysis found that planting a mixture of cover crop types was more effective than planting a single type. Additionally, planting a mixture of cover crop species, which are subcategories of cover crop types, was found to be more effective than planting a single species. Our analysis also unveiled a persistent, albeit diminishing, reduction in weed biomass even after the termination of cover crops. For weed density analysis, we used a fixed-effect model due to the absence of between-study heterogeneity and found a statistically significant reduction (45.4%) in weed density. Subgroup analysis revealed no significant difference in weed density control between legume and grass cover crop types.

A new approach for modelling weed suppression of cover crops

AbstractCover cropping plays an important role in Integrated Weed Management (IWM). Weed suppression of cover crops occurs by competition, physical barrier on the soil and allelopathy. Under favourable growing conditions, cover crops can provide similar weed suppression in the autumn‐to‐spring period as repeated stubble tillage and non‐selective herbicides. The objective of this study was to test if cover crop species with higher allelopathic potential can suppress weeds in the field with less shoot biomass than cover crop species with lower allelopathic effects. Data of cover crop shoot biomass, percentage of weed suppression in the field and reduction of weed seed germination in petri‐dish bioassays treated with cover crop extracts were analysed from 11 experiments. Weed suppression in relation to cover crop biomass was better predicted by a Weibul three‐parameter model than with the Cousens model. Raphanus sativus var. oleiferus, Sinapis alba, Fagopyrum esculentum and Phacelia tanacetifolia needed at least three‐fold more biomass than Avena strigosa for 80% weed suppression. Vicia sativa had the lowest weed reduction of only 62%. Aqueous extracts of A. strigosa had the highest inhibiting effect on weed seed germination followed by R. sativus. The lowest effect was observed for P. tanacetifolia. It is assumed that for A. strigosa allelopathy strongly contributes to weed suppression whereas for P. tanacetifolia and other cover crops, competition plays the major role for weed suppression. The model can help growers and consultants to mix cover crop species for the autumn‐to‐spring period. Under dry conditions, species such as A. strigosa can provide high weed suppression with low biomass. Under moist conditions, rapidly growing cover crops such as S. alba suppress most weeds and deliver high biomass.

Assessing relationships of cover crop biomass and nitrogen content to multispectral imagery

AbstractCover crops provide valuable roles in sustainable agriculture, provided they produce enough biomass. To accurately measure their services to field management, spatial estimates would be useful to producers. This study used multispectral drone imagery to produce maps of normalized difference vegetation index (NDVI), normalized difference red edge index (NDRE), and a digital surface model (DSM) of cover crop plots on sandy, Mid‐Atlantic soils. Cover crops included cereal rye (Secale cereale), mixtures of rye and crimson clover (Trifolium incarnatum), and mixtures of rye and hairy vetch (Vicia villosa). Their biomass was sampled in the spring of 2019, 2020, and 2021, dried, weighed, and analyzed for total nitrogen (N) content. Measurements of NDVI became saturated (i.e., reached a linear plateau) at 3.86 Mg biomass ha−1, NDRE at 5.72 Mg biomass ha−1, and the DSM at 5.11 Mg biomass ha−1. The measured N content became saturated at 80.9, 139.1, and 75 kg N ha−1 for NDVI, NDRE, and the DSM, respectively. Based on log transformations, NDVI was a stronger predictor of biomass and N, but not C:N. The NDRE was important for biomass, N, and C:N, while the DSM interactions with cover crop species helped predict both the N content and C:N of cover crop tissues. Accumulated growing degree days was important as an individual variable for biomass and N and as an interaction with cover crop species.

Mixture of winter cover crops reduces surface runoff and sediment production under no‐tillage system for Oxisols

AbstractOne of Brazil's efficient soil and water conservation practices is the no‐tillage system (NTS). Nonetheless, erosion during rainfall still causes soil and water losses in this system. Therefore, this study aimed to assess surface runoff in different cultivation systems and sediment production during rainfall events. In macro‐plot 1 (non‐terraced catchment [NTC]), we adopted the NTS management with up‐ and down‐slope farming without including mechanical runoff control practices, which most regional producers use. In macro‐plot 2 (best management practices [BMPs]), we optimized crop rotation by incorporating a mixture of cover crop species in autumn and implemented contour farming practices. In macroplot 3 (terraced catchment [TC]), we adopted the same soil management practices as the NTC macroplot, including mechanical runoff control using broad‐based terraces. We used rainfall data to create hyetographs, hydrographs, and sedimentographs, aiming to evaluate the impact of management practices on surface runoff and sediment production. The surface runoff was reduced by 81% (BMPs) and 88% (TC) compared to the NTC system. There was also a reduction in suspended sediment concentration, around 33% (BMPs) and 63% (TC), compared to the NTC system. Despite conservation systems have shown effectiveness in reducing surface runoff and sediment production, monitoring these systems during periods not influenced by the La Niña phenomenon is necessary to assess the impact of rainfall events on soils with conservation practices in extreme events. The study findings provide guidance and recommendations for agricultural producers and field technicians globally, offering criteria for selecting optimal soil and water management practices in no‐till systems. This promotes a conservation‐oriented approach to agriculture.

Influence of soil management on vegetative growth, yield, and wine quality parameters in an organic “Pedro Ximénez” vineyard: field and UAV data

The use of cover crops in vineyards is expected to increase due to the strong encouragement by European agricultural policy and their contribution to reducing soil erosion. This paper presents the results obtained over three years in a vineyard of the “Pedro Ximénez” variety organically grown in southern Spain. The influence on production, vigor, and grape quality of a seeded cover crop versus tillage was compared using field data and imagery acquired by an uncrewed aerial vehicle. The vines under tillage showed greater vegetative development and yield than those with cover crops between rows. The grapes from the vines under the cover crop treatment ripened earlier and presented higher values of total soluble solids, characteristics that can be useful in the protected designation of origin where the study field is placed. However, the strong yield reduction caused by the cover crop treatment encourages future research to explore other cover crop species that could contribute to improving soil properties without compromising the profitability of the vineyard. This is the first time that the influence of cover cropping on the agronomic and oenological parameters of organically grown white vineyard varieties such as “Pedro Ximénez” has been assessed using field and UAV data.

Cover crops terminated with roller-crimper to manage Cynodon dactylon and other weeds in vineyards.

Using cover crops in organic vineyards can provide many advantages, including weed suppression. However, their effectiveness may depend on the weed community, the cover crop species and the termination method. The most common practice for cover crop termination is shredding, but rapid residue decomposition can allow noxious species like Cynodon dactylon to proliferate during summer and compete with the vines. The use of roller-crimpers as an alternative method can be effective in some cropping systems, but no studies have focused on their use in the inter-row of vineyards. The objective of this study was to evaluate the effectiveness of seven cover crops (spontaneous, Avena strigosa, Hordeum vulgare, Lolium multiflorum, Phacelia tanacetifolia, Sinapis alba and X Triticosecale) and two termination methods (shredding or roller-crimper) in managing C. dactylon during summer. In 2020, rolled A. strigosa, P. tanacetifolia and the spontaneous flora limited the coverage of C. dactylon more than shredding (increases of 3% and 18% in C. dactylon cover from July to September in rolled and shredded cover crops, respectively), while in 2021, rolling was better than shredding for all cover crop species in September (5% and 18% increases, respectively). Roller-crimping cover crops was an effective method to control C. dactylon in vineyard inter-rows but it did not consistently work for all cover crops in both years. Our study is one of the first to test the efficacy of roller-crimpers to manage summer weeds in vineyards. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Soil texture, fertilization, cover crop species and management affect nitrous oxide emissions from no-till cropland

Cover crops reduce nitrate leached, but effects on nitrous oxide (N2O) emissions are mixed. Cover crops can reduce N2O emissions by reducing levels of mineral nitrogen (N) and surface soil moisture during spring. Cover crops can also increase N2O emissions by adding organic substrates, releasing N during decomposition, or increasing summer soil water content. Winter-killed cover crops can increase soluble organic C and N during periods of typically low microbial activity. We hypothesized that planting a cover crop mix of radish (Raphanus sativus)-crimson clover (Trifolium incarnatum)-rye (Secale cereale) would increase direct N2O emissions relative to no cover crop, and result in lower direct and indirect N2O emissions than planting radish alone. We also hypothesized that extending the cover crop growing season, by planting earlier and killing later, would increase direct N2O emissions during winter, decrease direct N2O emissions during summer, and decrease indirect N2O emissions. To address these hypotheses, we conducted two field experiments (on sandy and silty soils) over four site-years. We measured cover crop biomass and N content, soil mineral N concentrations, soil moisture, green canopy cover, soil porewater nitrate, direct N2O emissions, and estimated indirect N2O emissions. Nitrous oxide emissions were ~ 7.8 times greater at the silty than the sandy sites due to greater soil moisture retention. Site-years with high radish biomass exhibited greater direct N2O emissions than sites with low radish biomass following winter-kill. Indirect N2O emissions were decreased ~7 % by planting cover crops and by ~70 % by planting cover crops early. Fertilizer induced emission peaks were 8.2 times greater than all previous N2O emissions combined at a silty site. Our results suggested that soil texture and fertilization played an important role in direct N2O emissions, while cover crop species, biomass, and timing played a more important role in NO3 leached, and thus, indirect N2O emissions.

Enhancing estimation of cover crop biomass using field-based high-throughput phenotyping and machine learning models.

Incorporating cover crops into cropping systems offers numerous potential benefits, including the reduction of soil erosion, suppression of weeds, decreased nitrogen requirements for subsequent crops, and increased carbon sequestration. The aboveground biomass (AGB) of cover crops strongly influences their performance in delivering these benefits. Despite the significance of AGB, a comprehensive field-based high-throughput phenotyping study to quantify AGB of multiple cover crops in the U.S. Midwest has not been found. This study presents a two-year field experiment carried out in Eastern Nebraska, USA, to estimate AGB of five different cover crop species [canola (Brassica napus L.), rye (Secale cereale L.), triticale (Triticale × Triticosecale L.), vetch (Vicia sativa L.), and wheat (Triticum aestivum L.)] using high-throughput phenotyping and Machine Learning (ML) models. Destructive AGB sampling was performed three times during each spring season in 2022 and 2023. An array of morphological, spectral, thermal, and environmental features from the sensors were utilized as feature inputs of ML models. Moderately strong linear correlations between AGB and the selected features were observed. Four ML models, namely Random Forests Regression (RFR), Support Vector Regression (SVR), Partial Least Squares Regression (PLSR), and Artificial Neural Network (ANN), were investigated. Among the four models, PLSR achieved the highest Coefficient of Determination (R2) of 0.84 and the lowest Root Mean Squared Error (RMSE) of 892 kg/ha (Normalized RMSE (NRMSE) = 8.87%), indicating that PLSR could be the most appropriate method for estimating AGB of multiple cover crop species. Feature importance analysis ranked spectral features like Normalized Difference Red Edge (NDRE), Solar-induced Fluorescence (SIF), Spectral Reflectance at 485 nm (R485), and Normalized Difference Vegetation Index (NDVI) as top model features using PLSR. When utilizing fewer feature inputs, ANN exhibited better prediction performance compared to other models. Using morphological and spectral parameters as input features alone led to a R2 of 0.80 and 0.77 for AGB prediction using ANN, respectively. This study demonstrated the feasibility of high-throughput phenotyping and ML techniques for accurately estimating AGB of multiple cover crop species. Further enhancement of model performance could be achieved through additional destructive sampling conducted across multiple locations and years.

Cover crop monocultures and mixtures enhance bacterial abundance and functionality in the maize root zone.

Cover cropping is an effective method to protect agricultural soils from erosion, promote nutrient and moisture retention, encourage beneficial microbial activity, and maintain soil structure. Re-utilization of winter cover crop root channels by maize roots during summer allows the cash crop to extract resources from distal regions in the soil horizon. In this study, we investigated how cover cropping during winter followed by maize (Zea mays L.) during summer affects the spatiotemporal composition and function of the bacterial communities in the maize rhizosphere and surrounding soil samples using quantitative polymerase chain reaction (PCR), 16S ribosomal ribonucleic acid (rRNA) gene amplicon sequencing, and metaproteomics. We found that the bacterial community differed significantly among cover crop species, soil depths, and maize growth stages. Bacterial abundance increased in reused root channels, and it continued to increase as cover crop diversity changed from monocultures to mixtures. Mixing Fabaceae with Brassicaceae or Poaceae enhanced the overall contributions of several steps of the bacterial carbon and nitrogen cycles, especially glycolysis and the pentose phosphate pathway. The deeper root channels of Fabaceae and Brassicaceae as compared to Poaceae corresponded to higher bacterial 16S rRNA gene copy numbers and improved community presence in the subsoil regimes, likely due to the increased availability of root exudates secreted by maize roots. In conclusion, root channel reuse improved the expression of metabolic pathways of the carbon and nitrogen cycles and the bacterial communities, which is beneficial to the soil and to the growing crops.

Performance of Common Bean Cultivated in Succession to Cover Crops

Purpose: The present research aims to evaluate the biomass production and nutrient uptake by different cover crops, as well as to verify the effects of straw on bean productivity. Method: The experimental design was completely randomized, consisting of sowing beans on straw four cover crops (Crotalaria ochroleuca, Pigeon pea, Mucuna gray and Lab-lab) + control, with five replications. Results and conclusion: The Pigeon pea species has great potential for dry matter production and ability to absorb and accumulate phosphorus in the leaves in full bloom. The straw of the species Crotalaria ochroleuca, Pigeon pea and Mucuna cinza contributed significantly to the productivity of common bean cultivated in succession, as well as represent an alternative to reduce the dependence on synthetic fertilizers and increase the sustainability of agricultural systems. Implications of the research: The search for maintaining or increasing crop production through the adoption of conservation practices with emphasis on the cultivation of cover crop species is emphasized as an efficient strategy for nutrient cycling, improving soil health and increasing productivity with sustainability assumptions. Originality/value: The results obtained in this study are relevant to the scientific community, contributing to the training of educators and development of students, especially in the area of agricultural and environmental sciences, serving as a scientific basis for the regional technological process.

Diversity of the Ground Cover Crop Nephrolepis Biserrata in Oil Palm Plantations on Various Soil Types

Ground cover crops play an important role in maintaining the ecological balance in oil palm plantations. Nephrolepis biserrata, as a cover crop species, has not been extensively studied, especially in relation to soil type and vegetation level. This study aimed to analyze the distribution and dominance of Nephrolepis biserrata in oil palm plantations on various soil and vegetation levels. This quantitative research was conducted in oil palm plantations in Central Kalimantan Province using a survey method with purposive sampling. Nine treatment combinations of three soil types (Histosols, Ultisols, and Spodosols) and three vegetation levels (low, medium, and high) were tested on 81 test plots. Data analysis includes diversity index (Ĥ), uniformity index (E), dominance index (C), importance value index (INP), and relative dominance (DR). The results of the research show that N. biserrata has good adaptability and dominance as a ground cover crop in the producing crop (TM) phase in oil palm plantations, especially on Spodosol-type soils. Nephrolepis exaltata and Nephrolepis biserrata showed the highest INP in Ultisols (76.65%; 7.64%), Spodosols (48.03%; 82.75%), and Histosols (61.34%; 23.98%). There are no cover crop species that dominate exclusively in all soil types (0.078-0.185). Ultisols have high cover crop diversity (3,107), whereas Spodosols (2,130) and Histosols (2,595) have medium diversity. Ageratum conyzoides (15.08%) and Paspalum dilatatum (10.06%) also had significant INP in all soil types. Different soil conditions influence the number of cover crop vegetation species and communities in oil palm plantations.

Cover crop species influences soil fungal species richness and community structure.

Despite the well documented link between cover cropping and soil microbiology, the influence of specific cover crop species on soil microbes remains poorly understood. We evaluated how soil fungal communities in a no till system respond to four cover crop treatments: no cover crop (REF), cereal ryegrass (CRYE), wild pennycress (WPEN), and a mix of pea, clover, radish, and oat (PCRO). Soil samples were collected from experimental plots following termination of cover crops from depths of 0-2 cm and 2-4 cm where cover crops had significantly increased soil organic matter. There was no significant interaction between soil depth and cover crop treatment on either alpha diversity or beta diversity. All cover crop treatments (CRYE, PCRO, and WPEN) enhanced soil fungal richness but only CRYE enhanced soil fungal diversity and altered the fungal community structure. Soil depth altered the fungal community structure but had no effect on fungal diversity and richness. Genus Fusarium which includes some of the most economically destructive pathogens was more abundant in REF and PCRO treatments compared to CRYE and WPEN. In contrast, genus Mortierella which is known to promote plant health was more abundant in all cover crop treatments relative to the REF. These findings demonstrate that cover cropping can increase soil fungal species richness and alter fungal community structure, potentially promoting the abundance of beneficial fungi and reducing the abundance of some plant pathogens within the genus Fusarium. These effects are dependent on cover crop species, a factor that should be considered when selecting appropriate cover crops for a particular cropping system.

Cover crop diversity for sustainable agriculture: Insights from the Cerrado biome

AbstractBrazil is one of the largest soybean producer of the world and the Cerrado biome has played a pivotal role in this expansion. Because of the economic and agronomic challenges associated with the maize production as a second summer crop in this region, cover crops are gaining popularity as a strategy to diversify the agricultural system while enhancing soil health. This study assessed the benefits of single species of cover crops and a mix of cover crop species in between harvest seasons to the soybean grain yield and nematode suppression. The study was carried out for 3 years in two locations within the Cerrado biome. We evaluated six cover crop treatments after soybean cultivation: (1) Mix of cover crops (Pennisetum glaucum, Crotalaria spectabilis and Urochloa ruziziensis), (2) P. glaucum (Pearl millet), (3) C. spectabilis, (4) U. ruziziensis (Congo grass) (5) Urochloa brizantha cv. Marandu (Marandu palisadegrass) and (6) U. brizantha BRS Paiaguás (Paiaguás palisadegrass). Pennisetum glaucum and U. brizantha cv. Marandu produced highest amounts of biomass on a 3‐year average. In one site, P. glaucum produced more biomass than other cover crops by 210%. Tropical grasses (U. ruziziensis, Marandu and Paiaguás), along with the cover crop mixture, exhibited intermediate biomass levels in the site with higher P. glaucum biomass production and did not differ from P. glaucum in the other site. Cover crops varied nutrient uptake depending on the species. Decomposition rates varied among cover crops as expected, with C. spectabilis decomposing rapidly and releasing substantial amounts nutrients, particularly nitrogen. In contrast, the cover crop mixture had a slower decomposition. The choice of cover crop significantly influenced soybean population and yield, with some variability across years and locations. The cover crop mixture consistently supported higher soybean populations and yields, highlighting its potential for enhancing soybean production, nutrient cycling and nematode suppression. It effectively reduced nematode abundance in soybean roots, highlighting its role in nematode management. Our findings emphasize the robustness and versatility of cover crop mixtures in mitigating weather variability across years and sites. They consistently performed well in terms of biomass production, nutrient uptake, soybean yields and nematode control. This study highlights the vital role of cover crops in the Cerrado ecosystem, enhancing soil health, crop productivity and environmental sustainability. The choice of cover crop species and mixtures offers a valuable tool for farmers seeking resilient and sustainable agricultural practices amid changing environmental conditions.

Differential phosphorus acquisition strategies of nine cover crop species grown in a calcareous and a decalcified chernozem

Background and aimsCover cropping is a strategy to increase soil phosphorus (P) use efficiency in agroecosystems. We investigated adaptations on P acquisition strategies of nine cover crops grown in a calcareous and a non-calcareous chernozem with low available P.MethodsThrough a 108-day pot experiment using a calcareous and a decalcified chernozem, we evaluated black oat (Avena strigosa Schreb.), white lupin (Lupinus albus L.), narrow-leaf lupin (Lupinus angustifolius L.), phacelia (Phacelia tanacetifolia Benth.), berseem clover (Trifolium alexandrinum L.), buckwheat (Fagopyrum esculentum Moench), linseed (Linum usitatissimum L.), ramtil (Guizotia abyssinica [Lf] Cass.) and white mustard (Sinapis alba L.) for their dry biomass production, tissue P concentration and uptake, and effects on soil pH, phosphatase activity, mycorrhiza infection rate and soil P fractions.ResultsCover crops differed in several parameters between the two soils. Dry biomass varied from 3.3 (white lupin) to 41.6 g pot-1 (mustard). Tissue P concentrations ranged from 0.046% (mustard) to 0.24% (clover). Species affected pH of both soils, ranging from − 0.66 to + 0.24. Acid phosphatase activity was higher in the decalcified soil, while alkaline phosphatases were higher in the calcareous soil. Root mycorrhizal infection rates ranged from 0 to > 50%. Most plants explored soil labile P exclusively, with organic P mineralization being more relevant in the calcareous soil.ConclusionWe confirm that cover crops favoured distinct strategies to access the predominant soil labile P forms in each soil. Mycorrhizal species were particularly efficient in the decalcified soil, while species with high phosphatase secretion accessed higher Po, especially in the calcareous soil.

Light partitioning strategies impact relative fitness of weeds and cover crops when drill-interseeding in corn

AbstractDrill-interseeding cover crops into corn (Zea mays L.) is an emerging establishment method in northern U.S. production regions. However, cover crop performance in interseeded systems remains variable, and creating environments that are conducive to cover crop but not weed growth is challenging. Cultural practices that partition resources between corn and interseeded cover crops have potential to improve performance if weeds are adequately managed. This study evaluated interactions among corn hybrids differing in leaf architecture (upright, pendulum), corn row spacing (76 cm, 152 cm), and interseeding timing (V3, V6) on light transmittance, relative fitness of cover crop species (cereal rye [Secale cereale L.], annual ryegrass (Lolium multiflorum Lam), red clover [Trifolium pratense L.]) and weeds, and corn grain yield at three U.S. Northeast locations. Results showed that light transmittance through the corn canopy was greater in 152-cm row spacing compared with 76-cm row spacing at the V6 growth stage, with the magnitude of difference increasing at the V10 corn growth stage. Corn hybrids had a marginal effect on light transmittance. The effect of row spacing and interseeding timing on fall cover crop biomass varied across cover crop species and locations. In 76-cm rows, interseeding earlier (V3) increased cover crop biomass production. The relative fitness of cover crops was greater than that of weeds in each combination of cultural practices that included narrow spacing (76 cm), whereas the relative fitness of weeds was greater than that of cover crops when interseeding in wide rows (152 cm). The effect of row spacing on corn yield varied among locations, with higher yields observed in 76-cm row spacing compared with 152-cm at two of three locations. Our results show that interseeding early (V3) on 76-cm row spacing can balance cover crop and corn production management goals, while placing cover crops at a relative fitness advantage over weeds.

Effect of crop management and climatic factors on weed control in sugarcane intercropping systems

ContextCover crops in intercropping systems have a high potential to manage weeds in tropical agroecosystems as an herbicide alternative. However, it still needs to be better investigated in sugarcane cropping systems. ObjectiveThis study assesses the weed control ability of cover crops in sugarcane intercropping systems depending on crop management and climate in tropical conditions. MethodsThis study was based on a set of eight experiments, including ten cover crop species, performed from 2012 to 2021 in three areas in Reunion Island (France) and comparing three inter-row management treatments: i) chemical weed control, ii) cover crops sown in the inter-row, and iii) low weed control. Mean weed and cover crop ground cover were measured during the entire crop cycle, and the complementary weed management practices (herbicide, manual weeding) were also recorded. Sugarcane yield and crop management were evaluated to assess the economic impact of a change in practice. ResultsMean weed ground cover was reduced by 51 % in the cover crop and chemical treatments compared to low control. Additionally, the cover crop treatment had an herbicide treatment frequency index lower by 37 % compared to chemical treatment but a higher number of manual weedings. In all treatments, weed cover increased with rainfall and temperature. In the cover crop treatment, a structural equation modeling approach allowed us to highlight the influence of cover crop (sowing date and species) and sugarcane management (crop cycle - plant or ratoon crop) on weed cover. Weed cover decreased with an increase in cover crop ground cover, which was higher for the early sowing date. Additionally, weed cover was lower in ratoon crops than plant crops but increased over time since intercropping was implemented. Finally, sugarcane yield was lower by 6 % in cover crop treatment compared to chemical treatment. The change in operating costs and revenues between these crop management induced a decrease in profits in intercropping compared to chemical cropping systems, variable according to the degree of mechanization. ConclusionsThis study highlights the predominance of management factors, compared with climate, to explain the effectiveness of weed control in sugarcane intercropping systems. ImplicationsDue to the change in weed cover over time, there is a need to assess the long-term sustainability of this practice and the potential change in weed communities.

Effectiveness of solitary and combined use of cover crop species to manage soilborne diseases in woody ornamental nursery production system

The understanding of how solitary and combined use of covercrop species and seeding rates influences soilborne diseases is lacking. Cover crops (crimson clover, triticale and crimson clover + triticale) were seeded in the field plots in September 2019 (Trial 1) and September 2021 (Trial 2) at two seeding rates (low and high) and a no cover cropped fallow served as a control. The soil was collected from all the plots in the following June. Red maple rooted cuttings were planted in nursery containers filled with those soils and plant health was evaluated with and without inoculation with Phytophthora nicotianae, Phytopythium vexans and Rhizoctonia solani. Plant height and fresh weight were measured, and plant roots were assessed for root rot severity (0–100% roots affected) and pathogen recovery. The number of fluorescent Pseudomonads present in soil samples was counted. Root rot severity and pathogen recovery were less with plants grown in cover cropped soil compared to non-cover cropped soil. Root rot severity caused by all three pathogens was least with the plants grown in the crimson clover and mixed cover cropped soil with the mixture being better than crimson clover. Moreover, plants grown in the high rate of cover cropped soil had less root rot severity compared to plants grown in low seeding rate cover cropped soil. Plant fresh weight was greater for plants grown in the high rate of crimson clover cover cropped soil and, in the mixture, compared to the non-cover cropped soil, whereas height was least affected. The Pseudomonad population was greatest in mixed cover cropped as well as in the high rate of cover cropped soil. Our findings suggest that a mixture of cover crop species and high seeding rate provides better service in suppressing root rot diseases likely associated with biological processes and nutrient availability.