Effects Of Cover Crops Research Articles

Applying potassium to ruzigrass prior to cotton reduces the nitrogen requirement and improves yield in a sandy soil under low water availability

Nitrogen (N) and potassium (K) are the nutrients most extracted by cotton, and low-fertility sandy soil demands new management strategies to improve fertilization efficiency and yield. The objective of this study was to evaluate the effects of cover crops (fallow, velvet bean, ruzigrass, ruzigrass + velvet bean, inoculated ruzigrass (Azospirillum brasiliensis), and inoculated ruzigrass (Azospirillum brasiliensis) + velvet bean), potassium application timing (pre-planting or post-planting), N rate (80 and 120 kg ha−1) and growing season on cotton yield, yield components, and yield quality. Cover crop dry matter production was higher in the first growing season (2018/2019) than in the second growing season (2019/2020). In the season with the worst climatic scenario (2018/2019), the anticipation K increased number bolls, boll weight and fiber yield under lower application N rates (80 kg ha−1). The inoculated ruzigrass + velvet bean consortium increased fiber yield when 120 kg ha−1 of N was applied at pre-planting K. The fiber quality parameters were influenced by growing season and management. Pre-planting K application increased short fiber content (SFI) with cotton under inoculated ruzigrass. In summary, K application prior to cotton planting in sandy soil in years of rainfall instability enables higher fiber yields under lower N rates (80 kg ha−1), but with regular rainfall K management did not affect cotton yield under inoculated ruzigrass + velvet bean at higher N rate (120 kg ha−1).

Successional effects of cover cropping and deep tillage on suppression of plant-parasitic nematodes and soilborne fungal pathogens.

Cover crops can suppress soilborne nematodes and fungal pathogens by serving as a poor host to pathogens and producing allelopathic compounds. Yet, cultural practices can influence their effectiveness. Cover crop and weedy fallow rotations and their interactions with deep tillage were evaluated from 2019 to 2021 in a three-season vegetable cropping system (spring tomato, fall squash, and winter cabbage) for their suppressive effects on soilborne diseases. Experimental plots were arranged in a split-plot 2 × 4 factorial design in randomized complete blocks. Whole-plot tillage treatments were shallow-tilled or deep-tilled. Subplots had two factors of crop rotations: rotation type (cover crop [spring or fall sunn hemp or winter rye] or weedy fallow) and rotation season. Independent of tillage practice, sunn hemp and weedy fallow reduced population density and root galling severity of root-knot nematode (Meloidogyne incognita) for the first subsequent vegetable compared to the all-vegetable rotation (P < 0.05) but had little effect on fungal pathogens. Fall sunn hemp had higher plant biomass and reduced gall severity for the second subsequent vegetable. Spring and fall sunn hemp improved vegetable yields. Winter rye only reduced ring nematodes (Mesocriconema spp.) population density in the first subsequent vegetable. Deep tillage reduced incidence of fungal pathogens of Rhizoctonia solani and Sclerotinia sclerotiorum, and population density of stubby-root nematode (Nanidorus minor). Sunn hemp is effective in suppressing M. incognita, whereas deep tillage can be used to suppress R. solani, S. sclerotiorum, and N. minor in vegetable production systems. © 2023 Society of Chemical Industry.

No-till cover crop effects on the thermal properties of a Paleudult

Soil thermal properties play an important role in crop productivity, but the influence of a multi-species cover crops (CCs) on these properties are not well understood. This study evaluated the effects of no-till CCs (winter wheat [Triticum aestivum L.], crimson clover [Trifolium incarnatum L.], triticale [Triticale hexaploide Lart], hairy vetch [Vicia villosa], oats [Avena sativa], and cereal rye [Secale cereale L.]) on soil physical (bulk density [BD], and volumetric water content [ϴ] at 0, −33, and −100 kPa soil water pressures) and thermal properties (thermal conductivity [λ], volumetric heat capacity [CV], and thermal diffusivity [D]). Soil samples were collected just before CC termination at 0–10, 10–20, and 20–30 cm depths from CC and no cover crop (NC) plots during 2021 and 2022. Results showed that, after 2 years, CCs reduced BD by 17% and increased ϴ at 0, − 33, and − 100 kPa soil water pressures by 23%, 25%, and 28%, respectively relative to NC management. Thus, λ under NC was 16%, 19%, and 20% higher at 0, − 33, and − 100 kPa soil water pressures, respectively, compared with CC management. Conversely, CV was 17%, 14%, and 15% higher under CC compared with NC management at 0, − 33, and − 100 kPa soil water pressures. Regression analysis further demonstrated that while plant root was the most important factor influencing λ at saturation, ϴ played the greatest role in λ at other soil water pressures. Expectedly, ϴ was the most important factor influencing CV at all measured soil water pressures. Conclusively, no-till CCs can improve laboratory measured soil thermal properties by moderating heat transfer.

Biological Methods of Ooptimization of Cultivation of Perennial Grasses in Agriculture of the Non-Chernozem zone

The possibility of using nitrogen of annual legumes for fertilizing perennial grasses (timofeevka meadow) by using them as cover crops has been established. By increasing the content of assimilable forms of nitrogen and other nutrients in the soil, they had a positive effect on the development of grasses in the autumn and spring periods, the formation of their biomass during vegetation, improving its quality, increasing the development of the root system of perennial grasses and the accumulation of nutrients in it. The effective effect of cover crops was traced for 4 years, the total increase in the mowing crop during this time amounted to over 120 kg/ha, the economic effect – of 17 thousand rubles.

Nitrogen release dynamics and carbon sequestration by legume and non-legume cover crops under pure and mixed planting conditions

Abstract Synchronizing crop residue decomposing and releasing nitrogen with subsequent cash crop needs provides benefits for ecosystems, but it is difficult to carry out. This study aimed to investigate the trend of decomposition of vetch (Vicia sativa), rye (Secale cereale) and mixed (rye + vetch) cover crop residues as well as nitrogen release after incorporating them into the soil during 12 weeks of the potato growth season by using the mesh bag method. Vetch residues decomposed very quickly in the spring and their nitrogen is released due to their higher nitrogen content and consequently a lower Carbon/Nitrogen (C/N) ratio. However, rye residues decomposed at a slower rate compared to mixed treatment, and their nitrogen content was immobilized mainly due to a higher C/N ratio. A better understanding of cover crops residues decomposition dynamics leads to maximizing the cover crop effects and higher nutrient uptake by subsequent main crops. The results of this study showed that the input level of nitrogen fertiliser can be reduced by implementing management strategies in farming potatoes and using cover crops, which will reduce the harmful environmental effects and increase the economic benefit for farmers.

Soil health tradeoffs may be minimal in phosphorus‐enriched Coastal Plain soils

AbstractSoil health practices can improve soil conditions and provide ecosystem services, but increased risk of phosphorus (P) loss can be an unintended consequence. We investigated conservation tillage and cover crops effects on soil P stratification, P accumulation at depth, and soil aggregation for sandy Coastal Plain soils from the Mid‐Atlantic United States soil cores from 10 agricultural fields with 0–15 years of conservation tillage or cover cropping were analyzed for Mehlich‐3 P and dry aggregate stability. We found no evidence that conservation tillage or cover cropping caused P stratification or accumulation in study fields that were already enriched with P prior to soil health implementation. Annual particulate, dissolved runoff, and leachate P loads decreased when estimated using the North Carolina Phosphorus Loss Assessment Tool assuming no‐till and cover crops (soil health) compared to conventional till and winter fallow (conventional). We suggest that soil health practices are unlikely to exacerbate P losses from high P Coastal Plain soils beyond their initial risk profile.

Field-scale nutrient loss assessment following cover crop and manure rate change

Eutrophication due to elevated nitrogen (N) and phosphorus (P) loss from croplands remains one of the most pressing water quality issues throughout the world. Understanding the effect of implementing conservation management practices is critical for meeting nutrient reduction goals as well as informing conservation programs and policies. A before-after-control-impact (BACI) analysis was used to evaluate the individual and combined effect of cover crops and manure application rate on discharge and nutrient loss using six water years (WY2014-WY2019) of measured data across four distinct drainage zones (1X–NCC; 1X–CC; 2X–NCC; 2X–CC) within an Ohio, USA, crop production field. White mustard significantly reduced mean monthly nitrate (NO3−-N) concentration regardless of manure application rate (i.e., 65 m3 ha−1 and 130 m3 ha−1). However, neither the use of white mustard, doubling manure rate, or the combination of the two had a significant impact on mean monthly drainage discharge, dissolved-reactive P (DRP), or total P (TP) loss. Seasonal analysis confirmed that NO3−-N concentration in the cover crop zones was signficantly less in fall, winter, and spring. However, significant increases in spring discharge, NO3−-N, DRP, and TP loads as well as TP concentration were noted with cover crop and greater manure rate treatments. These findings confirm that cover crops have a reducing effect on NO3−-N concentration but may not have any effect on addressing P concerns. Further research is warranted; however, this study highlights that the resource concern (e.g., N or P) should be considered prior to implementing cover crops as a conservation management practice.

Simulated impacts of winter rye cover crop on continuous corn yield and soil parameters

AbstractCover crops (CC) provide numerous ecosystem services such as improving soil health, reducing nutrient loss, increasing productivity, and mitigating greenhouse gas emission. However, adoption of CC has been hindered by perceived negative impacts on main crop productivity and additional production costs. This is partly attributed to the gap in current state of knowledge in CC and its interaction with main crop production under different biophysical conditions. In this study, Decision Support System for Agrotechnology Transfer model was used to evaluate the long‐term impact of cereal rye (Secale cereale L.) on corn (Zea mays L.) yield, soil organic carbon (SOC), nitrate leaching, soil water, and drainage for a range of climate, soil, and irrigation management in Eastern and Central Nebraska. A 30‐year (1991–2020) simulation showed no difference in corn yield and SOC between CC and no‐cover crop treatments at both sites under irrigated and rainfed conditions. However, CC resulted in reduction of N loss by up to 48% at the Eastern Nebraska Research and Extension Center and 24% at South Central Agricultural Laboratory under irrigation. Cereal rye has no significant effect on total soil water but, a significant reduction in cumulative subsurface drainage of 44% was determined at both sites. This study has shown the possible effect of cover crop on corn crop yield and soil properties over different regions in Nebraska. Future research extending the scope and geographic area is needed to test and quantify possible impacts of multiple CC species under diverse management and biophysical conditions.

Simulated effects of cover crops with no-tillage on soil and crop productivity in rainfed semi-arid cotton production systems

Cover cropping and no-tillage (NT) practices are promoted for soil health and environmental benefits. However, producing enough quantity of biomass to meet expected benefits can be a challenge in semi-arid cropping systems where water resources are limited, and producers have lingering questions regarding cover crop selection, termination timings, water use, and their subsequent effect on cash crop. The objective of this study was to assess the impacts of cover crops with NT on soil and crop productivity in a rainfed, continuous cotton (Gossypium hirsutum L.) system using the Denitrification Decomposition (DNDC) model. Treatments included: (a) conventional till (CT); (b) NT, and NT with the following cover crops: (c) Austrian winter pea (Pisum sativum L.) (Pea); (d) crimson clover (Trifolium incarnatum L.) (Clover); (e) hairy vetch (Vicia villosa L.) (Vetch); (f) a multi-species mixture (Mixture); and (g) winter wheat (Triticum aestivum L.) (Wheat). The DNDC model adequately simulated the seed cotton yield and cover crop biomass during calibration (root mean square error (RMSE) = 200 and 398 kg ha−1, respectively) and validation (RMSE = 277 and 270 kg ha−1, respectively). Stocks of soil organic carbon (SOC) and total nitrogen (TN) were simulated with Nash–Sutcliffe efficiency (NSE) of 0.91 and 0.78 during calibration, and with NSE of 0.88 and 0.75, respectively during validation. Long-term simulations revealed: (1) Vetch and Pea produced greater biomass and hence highest SOC and TN contents, which was followed by Mixture, Wheat, and Clover; (2) cotton yield in cover crop treatments was no different to that in non-cover crop treatments when cover crop was terminated about six weeks prior to cotton planting; (3) later termination of cover crops can result in greater cotton yield loss due to soil water depletion by cover crops. Overall, this study highlights the potential of conservation practices, such as cover crops and NT to improve soil health without significant loss in cotton yields.

Effect of natural weed and Siratro cover crop on soil fungal diversity in a banana cropping system in southwestern China.

Natural weed cover and a legume cover crop were examined to determine if they could impact soil fungal diversity as an indicator of soil quality in banana production. Banana in Yunnan Province, China, was grown under three treatments: conventional tillage (bare soil), natural weed cover (primarily goosegrass (Eleusine indica (L.) Gaerth)), or a cover crop (Siratro (Macroptilium atropurpureum (DC.) Urb.)). Analysis of the soil fungal communities between 2017 and 2020 was done by Illumina Miseq high-throughput sequencing. Most significant effects were in the intercropping area for the treatments, whereas it was rarely observed in the furrow planted with banana. Based on the Shannon and Simpson diversity indices, soil fungal diversity in the intercropping area significantly decreased following planting banana in 2017 with all three treatments. However, both the Shannon and Simpson diversity indices showed that there were significant increases in fungal soil diversity in 2019 and 2020 with natural weed cover or Siratro compared to bare soil. At the end of the experiment, significant increases in fungal genera with Siratro compared to bare soil were observed with Mortierella, Acremonium, Plectophaerella, Metarhizium and Acrocalymma, and significant decreases were observed with Fusicolla, Myrothecium, Exserohilum, Micropsalliota and Nigrospora. Siratro resulted in higher stability of the soil fungal microbiome by increasing the modularity and the proportion of negative co-occurrences compared to bare soil. For fungal guilds, Siratro significantly increased saprotrophs_symbiotrophs in 2019 and 2020 and significantly decreased pathogens_saprotrophs in 2020 compared to bare soil. Using Siratro as a cover crop in the intercropping area of banana helped maintain soil fungal diversity, which would be beneficial for soil health with more symbiotrophs and less pathogens in the soil. However, further research is needed to determine the long-term impact of weed or Siratro cover crop on the fungal soil ecosystem and growth of banana.

Cover cropping history affects cotton boll distribution, lint yields, and fiber quality

AbstractThere has been limited introduction of new cover crop species into cotton (Gossypium hirsutum L.) production within the last 30 years. Mounting evidence shows that traditional cover cropping species may be detrimental to cotton production, either by depleting soil fertility with crop removal, immobilizing minerals from high carbon residue, or excessive quantity of residue remaining at planting. The objective of this study was to determine the effects of growing a novel cover crop species, carinata (Brassica carinata A. Braun), as a winter annual cover crop for cotton rotation in the southeastern Coastal Plain. Over a 2‐year period, carinata, winter wheat (Triticum aestivum L.), and fallow covers were maintained over winter months, then rotated into cotton. Each year, seedcotton and lint yields were collected, along with subsamples for ginning and subsequent fiber quality analyses. Additionally, end‐of‐season plant mapping was conducted on plants from 1 m of row per plot to determine cover crop effects on boll formation, retention, and distribution, as well as canopy architecture. Results indicated that seedcotton and lint yield of cotton following carinata was greater than cotton following winter wheat, and lint yields of cotton following wheat were lower than cotton after fallow. Fiber quality was largely unaffected by preceding cover crop. End‐of‐season plant mapping indicated that cotton grown after carinata had more position 2 bolls, which correlated to greater lint yields. These results indicate that carinata can potentially serve as a new, more effective cover crop than winter wheat for cotton rotations in Coastal Plain soils.

Soil fertility and pomelo yield influenced by soil conservation practices

Abstract Exchangeable cations and soil nutrients leach out/lost in the raised bed soils system through irrigation water and rainwater. Cover crops or crop residue mulching are considered sustainable agricultural measures because they prevent soil degradation and compaction and increase the soil ecological diversity. However, the impact of these on soil quality in fruit orchards in the Vietnamese Mekong Delta is not well studied. The present work aimed to assess the effect of cover crops (grass, pinto peanut) and rice straw mulching on change in soil chemical properties and productivity of pomelo. The 3-year (2019–2021) field experiment was conducted at Phu Huu Commune, Chau Thanh District, Hau Giang Province, Vietnam. Four treatments, control (no-cover crop), grass cover crop, mulching with rice straw (MRS), and pinto peanut cover crop were used. Soil samples were collected from the depth of 0–20 and 20–40 cm for analyzing soil pH, total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), and soil organic matter (SOM). Results showed that MRS or cover crop by pinto peanut significantly decreased soil acidity in the topsoil layer. Soil fertility properties (TN, TP, AP, and SOM) at the depth 0–20 cm were greatly improved after the application of the mulched rice straw and cover crop by legume, thus improving pomelo yield. Further study is required to understand the effects of the cover crop with pinto peanut and rice straw mulching on the physical and biological properties of soil as well as nutrient uptake of pomelo orchards.

Opportunities and Challenges for Cover Cropping in Sustainable Agriculture Systems in Southern Australia

Southern Australian farming systems operate predominantly under Mediterranean climatic conditions, which limit the choice of cover crops suitable for enhancement of ground cover and soil moisture retention, erosion control, atmospheric soil nitrogen (N) fixation, and weed suppression between cash crop rotations. Given that the successful establishment of cover crops is climate-driven and also influenced by edaphic factors such as soil pH and salinity, there has been increased interest by southern Australian producers in identifying potential cover crop species well adapted to specific Australian farming systems, which provide vital ecosystem services and sustainable economic benefits through the improvement of soil properties. This review summarises recent findings on cover crop inclusion in diverse farming systems in southern Australia, including continuous and mixed broadacre cropping as well as viticulture and horticulture systems, to identify opportunities and limitations related to their use. Cover crop inclusion in viticulture and pasture systems with lower moisture stress was observed to benefit the subsequent cash crop through enhanced production potential. Long-term, multi-site field experimentation incorporating summer cover crops in winter crop rotations showed that cover crops enhanced ground cover and soil water infiltration in some locations across southern Australia while sometimes increasing winter crop yield, suggesting that soil type and regional climatic conditions greatly influenced the delivery of multiple cover crop benefits. Collectively, these studies have suggested a need for longer-term field evaluations using multiple cover crop species and investigations of termination options under varying environmental and soil conditions to better quantify the legacy effects of cover crops.

Understanding the effect of cover crop use on prevented planting losses

AbstractCover cropping has the potential to improve resilience of agriculture to climate‐change‐induced extreme weather events. However, rigorous quantitative evidence on the resilience effect of cover crops is still lacking. Using a novel data set that combines satellite‐based cover crop information and county‐level crop insurance data, we examine the impact of planting cover crops on prevented‐planting‐related losses that are typically caused by heavy rainfall events. The US federal crop insurance program offers “prevented planting” coverage, which pays indemnities if insured growers are unable to plant their crop due to adverse weather. Linear fixed effects models, instrument‐based estimation methods, long‐difference models, and a number of other robustness checks are utilized in the empirical analysis to achieve the study objective. Our findings suggest that counties with higher cover crop adoption rates tend to have lower levels of crop insurance losses due to prevented planting. The resulting reduction in prevented planting risk also becomes larger with longer term, multiyear cover crop use. These results support the notion that cover crops improve soil conditions such that the likelihood and magnitude of prevented planting losses decrease. We posit that the ability of cover crops to handle excess moisture (i.e., through better water absorption and improved water infiltration in the soil) is the main factor in its ability to reduce prevented planting losses in the US Midwest.

Cover crop effects on infiltration, aggregate stability, and water retention in the Lower Mississippi River Valley

AbstractCover crops are widely considered to improve soil health in the form of erosion control, organic matter additions, and improving water‐holding capacity. Despite the generally well‐documented benefits, cover crops remain under‐studied in the Lower Mississippi River Valley (LMRV), an area historically dominated by intensive cultivated agriculture, with soils prone to erosion, and where the need for irrigation has led to unsustainable aquifer withdrawals. The objective of this study was to evaluate cover crop (with cover crops [CC] and without cover crops [NCC]) effects on near‐surface soil physical, chemical, and hydraulic properties. Soil sample collection and in situ measurements were conducted, once per site, between May 2018 and May 2019 across four locations within the LMRV portion of eastern Arkansas. Overall and steady‐state infiltration rates were unaffected (p &gt; .05) by cover‐crop treatment. Across all locations, extractable soil Na content in the top 10 cm was greater (p ≤ .05) with NCC (31.6 kg ha−1) compared with CC (21.6 kg ha−1). Averaged across treatment and soil depth (0 to 5 and 5 to 10 cm), water‐stable aggregate concentration in the 0.25‐ to 0.5‐ (0.101 g g−1) was 1.5 times greater (p ≤ .05) than that in the 1.0‐ to 2.0‐mm size class (0.068 g g−1). Though many soil properties did not significantly differ between CC treatments due to their collective variations, results of this study demonstrate the wide‐spread implications of CC use on physical, chemical, and hydraulic properties across a region.

Soil Carbon and Nitrogen Forms and Their Relationship with Nitrogen Availability Affected by Cover Crop Species and Nitrogen Fertilizer Doses

Cover crops and N fertilization strongly impact the forms of soil organic C and N and their availability, which change the responses of plants to N fertilization and soil organic C accumulation. Our study objectives were to evaluate the effects of cover crops and N doses on soil total and soluble C and N contents, N fractions, and potentially available N in a long-term no-till experiment. The experiment was conducted in a randomized block design with split plots and four replicates. The main treatments were cover crops species, jack bean, lablab bean, millet, velvet bean, and fallow cultivated prior to maize. Secondary treatments included two doses of mineral N (0 and 120 kg ha−1). Soil samples were collected at depths of 0–5, 5–10, 10–20, and 20–40 cm, which were analyzed for total and water-soluble C and N contents, N fractions (acid hydrolysis method), and potentially available N (hot KCl solution and direct steam distillation methods). Cover crop velvet bean resulted in the highest soil organic carbon levels, and cover crop millet plus fertilization resulted in the highest levels of soil total N. The amino sugar was the largest N fraction, which decreased by 8% with N fertilization. The soluble C and N content strongly correlated with total and available N content. The changes in soil N were influenced by cover crop species and fertilization and the interactions of both, so the combination of fertilization regime and cover crops must be chosen with care. Additionally, legumes are a good source of plant and soil N in systems with low input of N via fertilizer; however, the combination of N fertilizer with legumes can reduce soil N reserves, leading to its long-term depletion.

Cascading Effects of Cover Crops on the Subsequent Cash Crop Defense against the Polyphagous Herbivore Fall Armyworm (Spodoptera frugiperda).

Recent studies have started to show that the benefits of cover crops can cascade to the cash crop growing seasons. However, the impact of cover crops on the subsequent cash crop defense against herbivores is not well understood. To test this, we conducted a field and laboratory study to assess the possible cascading effects of cover crops such as Vigna unguiculata, Sorghum drummondii, Raphanus sativus, and Crotalaria juncea on the subsequent cash crop (Sorghum bicolor) defense against the notorious polyphagous herbivore fall armyworm (Spodoptera frugiperda) across three farms in the Lower Rio Grande Valley. Our field and laboratory studies showed that the cash crop planted in the cover crop treatment differentially affected S. frugiperda. More specifically, we found that cover crops have positive effects on the growth and development of S. frugiperda on the subsequent cash crop, including both larval and pupal parameters. However, our experiments on physical and chemical defenses in cash crops failed to show any significant differences between cover and control. Collectively, our results add an additional line of evidence on the effects of cover crops on pest dynamics outside the cash crop season, a key consideration for the selection and management of cover crops and cash crops, whose underlying mechanisms need to be examined further.

Effect of cover cropping on soil organic matter characteristics: Insights from a five-year field experiment in Nebraska

Cover crops are increasingly incorporated into crop rotations to improve soil health including the postulated positive impact on soil organic carbon (SOC) storage. However, a consistent positive response of SOC to cover cropping was not observed in several studies, necessitating further clarification of mechanisms by which cover crops impact soil organic matter (SOM) dynamics. In this study, we evaluated the effect of five years of winter cover cropping within a corn-soybean rotation in Nebraska under no-till on SOC and nitrogen (N) storage in the bulk topsoil (0–10 cm depth) as well as in particulate (free and occluded), water-extractable, and mineral-associated organic matter fractions. Furthermore, cover crop effects on potential C and N losses from the topsoil in form of CO2 and N2O emissions and leached organic C and N were evaluated. The different SOM fractions were analyzed for their functional group composition using diffused reflectance infrared Fourier transform spectroscopy to account for potential changes in the SOM composition due to cover crops. Our results indicated no effect of cover cropping on C and N losses (gaseous and leaching) and on bulk SOC and total N storage five years after implementation. Differences were detected for the SOM fractions, with a positive effect of cover crops on the amount of water-extractable organic matter. The spectroscopic results suggested a significant cover crop effect on the composition of free particulate organic matter fraction. Both fractions seem to be suitable for detecting early changes in SOM characteristics due to cover cropping under the studied conditions. A significantly measurable impact on bulk SOC and N storage in 0–10 cm depth for the studied corn-soybean systems might require more than five years of cover cropping, or management changes that target an increase in cover crop biomass production and input into the soil.

Long-term cover cropping improved soil bacterial community and soil multifunctionality in a Carya cathayensis plantation

Chinese hickory (Carya cathayensis Sarg.), a nut tree unique to China, is an important source of high-class nuts and oil. However, the intensive management practices, especially removing all the understory, lead to the soil degradation in Chinese hickory plantation. Thus, cover cropping is applied to improve and maintain soil quality and productivity. Soil multifunctionality (SMF) is a practical index to comprehensively assess different soil environmental factors with complicated interactions. However, the long-term effects of cover cropping on soil bacterial community and SMF in Chinese hickory plantations remain unknown. In this study, a field experiment was conducted in a Chinese hickory plantation in Zhejiang province, China, from 2011 to 2021. The effects of cover crops including oilseed rape (Brassica chinensis, OR), Chinese milk vetch (Astragalus sinicus, CMV), and the mixtures of oilseed rape and Chinese milk vetch (OC) on the soil bacterial community and SMF were compared with no cover crop (NC). We employed high throughput sequencing of 16 S rRNA to study soil bacterial community, and adopted the averaging approach to determine the SMF value based on soil carbon (C) and nitrogen (N) storage, potential enzymatic activity, and active nutrient pool. The results revealed that long-term cover cropping significantly improved soil C and N content, which stimulated the soil potential enzymatic activity. And consequently, soil labile nutrient concentrations were increased, suggesting better soil active nutrient pool. The proliferation of bacteria utilizing easily-decomposed organic matter was therefore promoted. Hence, SMF was significantly improved by cover cropping. And OC effectively combined species-specific functions including nutrient retention and utilization. Consequently, OC showed the best improvement of soil environmental factors including C and N storage, active nutrient pool, and potential enzymatic activity among cover cropping treatments. It is therefore that OC manifested better SMF than sole cover crops strategies. Random forest modeling and partial least squares path modeling (PLS-PM) revealed that soil C storage, pH, and potential enzymatic activity, were dominant predictors of SMF. Additionally, C and N storage, and pH directly influenced bacterial richness and composition positively or negatively. This study provides insight into the effects of different cover crops on the soil bacterial community and SMF in Chinese hickory plantations, and highlighted the great potential of the legume-cruciferae cover cropping strategy on SMF improvement. These findings have implications for the optimization of sustainable forest management practices in degraded forest plantations.

Strip-tillage and Zonal Cover Cropping Effects on Organic Squash Production

Zonal management of cereal–legume cover crop mixtures may help address weed and nitrogen management challenges common in organic reduced tillage systems. During a field study conducted over 3 years in Michigan, we evaluated the effects of cover crop management, tillage, and supplemental mulch on organically produced acorn squash (Cucurbita pepo). During the fall season before squash production, rye (Secale cereale L.) and vetch (Vicia villosa Roth) cover crop mixtures were sown in two distinct spatial arrangements: a “mixed planting,” in which seeds were sown in the same rows, and a “zonal planting,” in which vetch was planted only in the in-row zone and rye was planted only in the between-row zone of the subsequent squash crop. During the following spring season, cover crops were mowed, and four tillage and cover crop management combinations were established: full-width tillage with the mixed planting of rye–vetch (full-till mixed); strip-till with the same mixed planting (strip-till mixed); strip-till with the rye–vetch zonal planting (strip-till zonal); and strip-till with the zonal planting and additional rye mulch added between crop rows immediately after crop establishment (strip-till zonal plus rye). The strip-till mixed treatment resulted in yields equivalent to those of the full-till mixed treatment despite lower available nitrogen and greater early weed competition in some cases. Within strip-till treatments, zonal planting of rye–vetch provided no benefits relative to full-width planting (treatment 2 vs 3) and resulted in lower total cover crop biomass, a higher density of escaped weeds, and lower squash yields during 1 of 3 years. Supplemental rye mulch improved weed suppression and yields in strip-till zonal treatments and resulted in yields equivalent to those of the full-till mixed treatment in all years, but it provided no benefits relative to strip-till mixed. Our results demonstrate that strip-till organic squash production can produce yields equivalent to full-till production in Northern climates, but that zonal planting and supplemental mulch have limited benefits for addressing ongoing weed and nitrogen management challenges. Growers must weigh costs associated with these challenges against potential benefits for soil and pest regulating ecosystem services before adopting these agricultural conservation practices.