Cover Crop Biomass Research Articles

Cover crops can produce livestock forage in Chinese subtropical regions

AbstractIt is common in South China that rice (Oryza sativa L.) fields are seeded with a cover crop following autumn harvest. The objective was to compare the effects of different no‐tillage methods on cover crop yield, nutritive composition, and silage fermentation quality of forage wheat (Triticum aestivum L. cv. Shimai‐1) and Italian ryegrass (Lolium multiflorum L.). Cover crops were planted in winter fallow paddy fields 9 (NT9) and 5 (NT5) d prior to rice harvest and 1 d after rice harvest. Cover crops seeded prior to harvest were no‐tillage planted and cover crops seeded after rice harvest were either no‐tillage (NT1) or seeded using conventional techniques (CT1; plow followed by seeding). The cover crop biomass was determined before rice sowing in spring. Compared to NT9 and NT5, the dry matter (DM) and crude protein (CP) yields of NT1 and CT1 were slightly higher. Compared to Italian ryegrass, forage wheat had high relative feed value and DM yield. The neutral detergent fiber concentration of NT9 and NT5 was higher than NT1 and CT1 (P < .05), whereas the water‐soluble carbohydrates (WSC) concentration was lower than NT1 and CT1 (P < .05). The CP, crude fiber, and WSC concentrations of forage wheat were lower than Italian ryegrass (P < .05). Interaction between years and cover crop type were observed in silage fermentation quality (P < .05). The best sowing method for forage wheat and Italian ryegrass on winter fallow paddy fields was no‐tillage sowing after rice harvest, based upon the present study.

Nitrogen-15 labelling and tracing techniques reveal cover crops transfer more fertilizer N to the soil reserve than to the subsequent crop

Estimating the capacity of cover crops (CC) to capture soil nitrogen (N) and to transfer captured N to subsequent crop remains a challenge because CC biomass production, N content and decomposition rate vary depending on environmental conditions and management practices. The objectives of this study were (1) to compare biomass production and N accumulation by a mixture of red and white clovers intercropped with barley, and oat, field pea and oilseed radish grown as catch crops after barley harvest, (2) to determine the capacity of different CCs to catch and transfer fertilizer N (mineral or pig slurry) to subsequent wheat and the soil reserve, and (3) to determine the influence of CC type on yield of spring wheat in the next year. A 2-y crop rotation (barley – wheat) was repeated twice on a sandy loam using 15N-labelled fertilizers applied at the time of CC establishment. Fertilization increased above-ground biomass yield in oat and oilseed radish, but had little effect on legume CCs. The legume CCs accumulated more total N in their biomass (63–127 kg N ha−1) than non-legume CCs (47–68 kg N ha−1). However, oat and oilseed radish were more efficient at capturing the applied fertilizer 15N (33–51 %) than legume CCs (2–36 %). Intercropped clovers resulted in the largest increases in subsequent wheat yields (23–92 %), followed by oilseed radish and field pea. At the end of the 2-y rotation (wheat harvest), the recovery of fertilizer 15N by subsequent wheat was < 10 %, whereas 26–60 % were still present in the 0−30 cm soil layer. We conclude that non-legume CCs have a good capacity to capture applied fertilizer N, whereas legume CCs (especially clovers) had a limited capacity. Nevertheless, clovers CC resulted in the greatest wheat yields in the following year, likely due to efficent transfer of symbiotically fixed N and improved soil quality, whereas fertilizer N captured by non-legume CCs was mainly routed to the soil N reserve, with potential to supply N to subsequent crops through a legacy effect.

Soil biological response to multi-species cover crops in the Northern Great Plains

Farmers in semi-arid regions are experimenting with cover crop mixtures as partial summer fallow replacement, with the goal of increasing soil biological activity. We compared extracellular enzyme activity, microbial biomass, potentially mineralizable nitrogen (PMN) and mycorrhizal colonization levels after growing cover crops comprised of one or four functional groups. We asked whether cover crops can alter those soil processes and components relative to fallow during the cash crop growing season, and whether a cover crop mixture (CCM) will have a greater impact than a single-species legume green manure (LGM) after one and two rotations with wheat. Cover crops were planted at two sites in Montana April 2012 and May 2014, and at two additional sites in May 2013, and April 2015, terminated at each site approximately 60 days after seeding. Wheat was the cash crop for the following growing season. Cover crop treatments included a fallow control, a sole pea LGM, and a FULL mix consisting of eight species, with two species of each of four functional groups. Four additional treatments of single functional groups were compared following the second rotation of cover crops. The geometric mean of soil enzyme activity increased after cover crops relative to fallow (1.1–1.3 fold) at two sites after the first rotation, and by 1.1–1.4 fold after the second rotation at three sites. At the fourth site, the geometric mean of the FULL mix was greater than LGM or fallow by 1.4 and 1.5 fold. The response of individual enzymes was less consistent. Microbial biomass and PMN increased after LGM and/or FULL at three of eight site-years, by 1.2–1.7 for microbial biomass and 1.6–2.1 for PMN. Mycorrhizal colonization of wheat increased in at least one cover crop treatment relative to fallow at four of six site-years, and decreased in cover crops relative to fallow at one site. There were no differences in soil biological traits measured among single-functional-group treatments. Soil biological parameters were correlated with cover crop biomass in 7 of 16 comparisons at two sites after one rotation. After two rotations, 5 of 8 soil parameters were correlated with cover crop biomass at one site, with no correlations for the remaining sites. Precipitation declined 30–50 % from the first rotations at those three sites. Positive effects of cover crops on soil biological parameters in semi-arid systems may be measurable only when environmental conditions do not limit growth.

Advancing on‐farm research with UAVs: Cover crop effects on crop growth and yield

AbstractMore on‐farm research is necessary to determine the practical benefits and drawbacks of cover crops at the field‐scale. The objective of this study was to advance the use of unmanned aerial vehicle (UAV) platforms for evaluating the effects of cover crop biomass on crop growth and grain yield in two corn (Zea mays L.) fields and two soybean [Glycine max (L.) Merr.] fields in Illinois. Experiments were 17–29 ha in size with cover crop and non‐cover crop treatment strips replicated four times. Flights were conducted with a multispectral sensor at three early‐ to mid‐season crop growth stages. On the same day, 40 biomass samples were collected to ground‐truth reflectance data. Results indicated that normalized difference vegetation index (NDVI) could predict crop biomass (V3–V10 in corn, V5–R1 in soybean) with moderate accuracy (R2 = .40–.64) using an exponential model in corn and a linear regression model in soybean. Cover crops significantly (p &lt; .1) reduced early‐ to mid‐season corn and soybean NDVI at several sampling events, yet no yield penalty was detected across fields. Correlations between cover crops, crop growth, and grain yield were low and inconsistent when using NDVI maps and estimated biomass and N uptake maps. This study highlights an opportunity for utilizing high‐resolution datasets in on‐farm experiments to investigate the impact of cover crops on crop growth and yield on a field‐specific basis.

Ecosystem Services and Cash Crop Tradeoffs of Summer Cover Crops in Northern Region Organic Vegetable Rotations

Intensive production practices characterizing vegetable farming contribute to high productivity, but often at the expense of supporting and regulating ecosystem services. Diversification with cover crops may support increased resilience through soil organic matter (SOM) contributions and physical soil protection. Vegetable farming often includes spring and fall production, limiting establishment and productive potential of over-wintered cover crops that are more widely used in the USA. In northern climate vegetable systems, warm-season cover crops planted during short summer fallows could be a tool to build resilience via ecosystem service enhancement. This project evaluated summer cover crops in the northern USA (MN and WI) for biomass accumulation, weed suppression, and contribution to fall cash crop yield. Our study included four site years, during which we investigated the effects of four cover crop species treatments, grown for 30 (short duration, SD) or 50 days (long duration, LD) alongside bare fertilized and unfertilized control treatments: buckwheat (Fagopyrum esculentum) and sunn hemp (Crotalaria juncea) monocultures, and biculture of chickling vetch (Lathyrus sativus) or cowpea (Vigna unguiculata) with sorghum-sudangrass (sudex) (Sorghum bicolor x S. bicolor var. Sudanese). To quantify cover crop quantity, quality, and weed suppression capacity, we measured cover crop and weed biomass, and biomass C:N. To quantify effects on cash crops, we measured fall broccoli yield and biomass. Mean total biomass (cover crop + weeds) by site year ranged from 1,890 kg ha−1 in MN Y1 to 5,793 kg ha−1 in WI Y2 and varied among species in Y1 for both the SD and LD treatments. Most cover crops did not outcompete weeds, but treatments with less weeds produced more overall biomass. Data from Y1 show that cover crops were unable to replace fertilizer for fall broccoli yield, and led to reduced fall crop yield. Broccoli in Y2 did not reach maturity due to fall freeze. Summer cover crops, because of their biomass accumulation potential, may be used by farmers in northern climates to fit into cropping system niches that have historically been left as bare soil, but care with timing is necessary to optimize weed suppression and mitigate tradeoffs for cash crop production.

Interseeding Camelina and Rye in Soybean with Varying Maturity Provides Soil Cover without Affecting Soybean Yield

Low adoption to utilize cover crops interseeded into soybean (Glycine max (L.) Merr.), in the northern Plains in the USA, is due to a short growing season and a few adapted winter-hardy species. The objective was to evaluate the impact of interseeded winter camelina (Camelina sativa (L.) Crantz) and winter rye (Secale cereale L.) using different soybean relative maturities on soybean yield, canopy coverage, spring cover crop biomass, and subsequent wheat (Triticum aestivum L.) yield. Cover crops interseeded into early-maturing (0.4–0.8) soybean cultivars had more fall coverage compared with the 0.9 maturity cultivar, but the spring biomass was similar for all maturities. The soybean yield of the 0.9 cultivar was significantly higher, 2365 kg ha−1 compared with 2037 kg ha−1 for the 0.4 cultivar. Rye outperformed winter camelina and had higher fall canopy cover (15 vs. 7%), spring canopy cover (16% vs. 4%), and higher spring biomass (313 vs. 100 kg ha−1 dry matter). Spring wheat, after rye, yielded 90% of the check. It is not recommended to plant spring wheat following winter rye, but there was no negative yield effect from winter camelina. Interseeding cover crops into soybean in the northern Plains is possible but needs further research to optimize interseeding systems.

Short-term cover crop carbon inputs to soil as affected by long-term cropping system management and soil fertility

Cover crops (CC) increase soil fertility via recycling of nutrients such as nitrogen (N) and buildup of soil organic matter, whereby CC contributes to climate change mitigation. The carbon (C) input to soil occurs via the input of plant material (shoot and root) and via phyllo- and rhizodeposition. However, the quantity of phyllo- and rhizodeposition from CC is largely unexamined, although this component potentially has a large contribution to microbial stabilization of C. Isotopic labeling with 13C to trace C flows and 15N to determine N2-fixation was conducted to test the short-term effect of the inclusion of winter vetch as a legume species to a CC mixture. The CC mixtures were established in a long-term experiment (1997–2019) with varying use of manure and CC cropping to test the effect of soil fertility on the behavior of the newly established CC mixtures. A significant reduction in the relative net phyllo- and rhizodeposition was observed with higher soil fertility. Interestingly, the quantity of net phyllo- and rhizodeposition was also reduced with higher soil fertility due to the lower relative phyllo- and rhizodeposition, despite a significantly higher CC biomass. Importantly, adjusting for unrecovered root fragments more than halved the calculated phyllo- and rhizodeposition, indicating that many published estimates are substantially overestimated. The use of CC during autumn provides an important window for C storage with both the input of plant biomass and belowground C investment being drivers of C storage.

Interseeding cover crops in sugar beet

Sugar beet (Beta vulgaris L.) production leaves very little residue to protect the soil from erosion during late fall and early spring. Biomass from interseeded cover crops provides an opportunity to protect soils from erosion during the fallow period. A three-year field study was conducted to assess cover crop interseeding in sugar beet production systems under rainfed conditions in Ada, MN, USA. Specifically, the impact of cover crop interseeding time, early (mid-June) vs. late (late June or early July), and four species, winter pea (Pisum sativum L.), rye (Secale cereale L.), winter camelina [Camelina sativa (L.) Crantz], and brown mustard (Brassica juncea L.), on cover crop biomass and sugar beet root yield, sucrose concentration, and recoverable sucrose yield. Cover crop biomass accumulation in sugar beet varied across years depending on distribution of rainfall after interseeding. Considering all three years, above ground biomass of cover crops ranged between 28 kg ha−1 to 2347 kg ha−1 at sugar beet harvest. Early interseeded cover crops produced threefold greater cover crop biomass than late interseeded cover crops. Across years, mean aboveground biomass produced by species was from highest to lowest, winter pea > rye > brown mustard > winter camelina. The highest recoverable sucrose yield was observed with early-interseeded brown mustard (13.8 Mg ha-1), late-interseeded winter camelina (11.2 Mg ha-1), and late-interseeded rye (10.46 Mg ha-1) in 2018, 2019, and 2020 growing seasons, respectively. Three years of results have shown that sugar beet grown with interseeded cover crops will produce root yields comparable to the control with no cover crops. Cover crops had no negative impact on root yield and sucrose concentration, but the selection of species and planting time affected growth and cover provided by the cover crops. This study provides evidence that interseeded cover crops offer a good option for protecting the soil during fallow periods in sugar beet production systems, without negatively affecting sugar beet yield or quality.

Nutrient stoichiometry of a plant-microbe-soil system in response to cover crop species and soil type

AimsThe theory of ecological stoichiometry mostly builds on studies of natural terrestrial ecosystems, whereas only limited stoichiometry information is available in response to agronomic practices.MethodsWe designed a greenhouse experiment in order to disentangle the specific role of cover crop identity and soil characteristic in affecting nutrient stoichiometry of a plant-microbe-soil system.ResultsNutrient ratios of cover crop biomass were species-specific and the growth rate explained, for most species considered, the stoichiometric differences in response to soil type. In contrast, the nutrient stoichiometry of soil microbes was more homeostatic and did not respond to either cover crop identity or soil type. Compared to bare soil, the presence of cover crop enhanced microbial phosphorus immobilization in the clay-rich soil, whereas it promoted microbial carbon biomass and microbial nitrogen immobilization in the sandy-rich soil. A greater microbial cumulative respiration in clay soils, where a higher microbial biomass C at the beginning of the incubation was observed, suggested a major role of soil type, compared to cover crop identity, in affecting microbial metabolism.ConclusionsBy understanding the stoichiometric constraints in the plant-microbe-soil system, our findings can help to implement agro-ecological practices by selecting appropriate cover crop species in relation to soil type in order, for example, to avoid nutrient limitation due to microbial nutrient immobilization.

Quality of Tomato (Solanum lycopersicum L.) Changes under Different Cover Crops, Soil Tillage and Nitrogen Fertilization Management

The purpose of this study was to evaluate the interaction effects of winter cover crops (hairy vetch, subclover and black oat) and a bare soil, cover crop biomass management (incorporated into the soil or left on the soil surface as death mulch), and nitrogen (N) fertilization level (0, 75 and 150 kg ha−1 of N) on fruit yield and fruit quality parameters of processing tomato. Hairy vetch residues increased the yield (+57%), color index (+8%) and sugar/acidity ratio (+7%) of marketable tomato fruits compared to bare soil regardless of cover crop biomass management. Black oat residues determined a poor marketable yield, especially in tilled soil (on average, −26%, compared to bare soil) and they had a tendentially negative effect on some parameters of tomato quality (high firmness and titratable acidity, low color index and pH). Subclover residues, when incorporated into the soil, determined similar marketable fruit yield to bare soil, although they had a more favorable effect on the color parameters of tomato fruits. The increasing of the N fertilization level from 0 kg ha−1 of N to 150 kg ha−1 of N always positively influenced the tomato yield and fruit characteristics. The results suggest that hairy vetch, compared to other cover crops, had a positive influence on tomatoes and it could be part of an environmentally friendly management package for sustainable tomato cultivation in Mediterranean conditions.

Effect of cover-crop biomass, strip-tillage residue disturbance width, and PRE herbicide placement on cotton weed control, yield, and economics

AbstractConservation tillage adoption continues to be threatened by glyphosate and acetolactate synthase–resistant Palmer amaranth and other troublesome weeds. Field experiments were conducted from autumn 2010 through crop harvest in 2013 at two locations in Alabama to evaluate the effect of integrated management practices on weed control and seed cotton yield in glyphosate-resistant cotton. The effects of a cereal rye cover crop using high- or low-biomass residue, followed by wide or narrow within-row strip tillage and three PRE herbicide regimens were evaluated. The three PRE regimens were (1) pendimethalin at 0.84 kg ae ha−1 plus fomesafen at 0.28 kg ai ha−1 applied broadcast, (2) pendimethalin plus fomesafen applied banded on the row, or (3) no PRE. Each PRE treatment was followed by (fb) glyphosate (1.12 kg ae ha−1) applied POST fb layby applications of diuron (1.12 kg ai ha−1) plus monosodium methanearsonate (2.24 kg ai ha−1). Low-residue plots ranged in biomass from 85 to 464 kg ha−1, and high-biomass residue plots ranged from 3,119 to 6,929 kg ha−1. In most comparisons, surface disturbance width, residue amount, and soil-applied herbicide placement did not influence within-row weed control; however, broadcast PRE resulted in increased carpetweed, large crabgrass, Palmer amaranth, tall morning-glory, and yellow nutsedge weed control in row middles compared with plots receiving banded PRE. In addition, high-residue plots had increased carpetweed, common purslane, large crabgrass, Palmer amaranth, sicklepod, and tall morning-glory weed control between rows. Use of banded PRE herbicides resulted in equivalent yield and revenue in four of six comparisons compared with those with broadcast PRE herbicide application; however, this would likely result in many between-row weed escapes. Thus, conservation tillage cotton would benefit from broadcast soil-applied herbicide applications regardless of residue amount and tillage width when infested with Palmer amaranth and other troublesome weed species.

Estimating cover crop biomass nitrogen credits with Sentinel‐2 imagery and sites covariates

AbstractCover crops can positively impact productivity and the environment. While improved estimates of cover crop N benefits could help promote their adoption, little information is currently available at the broad scale. We conducted a multi‐site study to determine whether use of satellite images and site factors could fill this gap. Six spectral indices were extracted from Sentinel‐2 satellite imagery and used with modeling covariates to estimate cover crop properties and biomass N credits (biomass × N contents). The partial least squares regression (PLSR) models were calibrated and validated with samples from 42 cover crop fields located in the midwestern and northeastern United States collected in 2017–2018. Remote sensing (RS)‐derived spectral indices strongly correlated (r &gt; .7) with red clover (Trifolium pratense L.) but not with rye (Secale cereale L.) biomass. Growing degree days (GDDs), cover height, ground cover percentage, and temperature often had high importance (variable importance in projection &gt;1) in PLSR models. Model predictive power was limited for estimates of biomass N credits when data from all validation sites and cover types were used (adjusted [adj] R2 = .52). However, models for both biomass (adj R2 = .81) and biomass N credits (adj R2 = .89) were successful for red clover fields. This suggests N benefits could be more effectively modeled for specific cover crop types. We also found RS‐based estimation of C/N ratios performed moderately well when applied to the complete dataset (adj R2 = .54), suggesting a way to differentiate grass and legume cover crops that can potentially inform biogeochemical models.

Allelopathic potential of winter and summer cover crops on the germination and seedling growth of Solanum americanum

Sustainable weed management strategies are important for reducing chemical inputs and development of weed resistance. This study aimed to evaluate the effect of extracts from winter cover crops (cereal rye, black oat, forage turnip, and common vetch) and summer cover crops (jack bean, velvet bean, and brown hemp) on seed germination and seedling growth of glossy nightshade (Solanum americanum Mill), under controlled conditions. The aqueous extracts were produced from the shoot biomass of cover crops at concentrations of 0%, 25%, 50%, 75%, and 100%. Fifty S. americanum seeds were placed on Germitest paper moistened with 15 mL of each extract concentration. Cereal rye extract at the highest concentration reduced total germination to 43% and caused a 62% reduction in the germination rate index (GRI) of S. americanum. Velvet bean extract reduced germination, GRI, and seedling growth of S. americanum from the lowest concentration applied, while concentrations of 75% and 100% completely suppressed seedling development. Decomposing cereal rye and velvet bean cover crops have potential to suppress germination and growth of S. americanum. Efficient cover crops could reduce herbicide applications, and thus improve herbicide resistance management.

Cover crops increase tomato productivity and reduce nitrogen losses in a temperate humid climate

Although cover crops (CC) are a promising option for reducing N losses, CC impacts on N availability and subsequent yields are highly inconsistent. Therefore, in a medium-term CC experiment in Ontario, Canada, the effect of using annual CC six times over 8 years on N cycling and processing tomato yield and quality during CC and tomato growing seasons was assessed. The five treatments included no cover crop control (no-CC), oat, oilseed radish, winter cereal rye, and mixture (radish + rye). Cover crop biomass was sampled in fall (2014 and 2015) and spring (2015 and 2016). Cover crops did not decrease fall soil mineral N content but accumulated an avg. of 93.5 kg N ha−1 in above-ground tissues. In both fall seasons, greater (avg. 38%) above-ground N content from radish than the other tested CC suggests the enhanced ability of radish to scavenge N and mitigate N losses. Except radish C:N (32.3) in spring 2015, spring above-ground C:N (< 30) was favourable for mineralization. Despite greater C:N in spring 2015, soil mineral N content was greatest from radish (avg. 255 kg N ha−1) at June in both years. Although CC increased tomato marketable yield up to 22%, tomato above-ground N content did not increase with CC. In contrast to crop yield, tomato fruit quality was not impacted by CC treatments. Our results of greater or equal tomato yield with CC than no-CC suggests that integrating CC in cropping systems is an effective approach to maintain and potentially enhance agroecosystem resiliency in the long-term.

Multispecies cover cropping promotes soil health in no-tillage cropping systems of North Carolina

Moving agricultural production systems toward a greater level of soil health is needed for sustainability. Conservation agricultural systems utilizing no or minimum tillage are an important step forward, but enhancing carbon (C) inputs with diverse cover crops and facilitating biologically active nitrogen (N) cycling are also needed. Summer cash-crop systems, particularly in the warm-humid region of the southeastern United States, may benefit from multispecies winter cover cropping if sufficient biomass were produced. We implemented a research and demonstration project utilizing multispecies cover cropping in 15 counties of North Carolina during 2015 to 2019 to assess biomass production and its effect on surface-soil properties. Winter cover crop biomass production was variable among locations, but exceeded 3,790 kg ha–1 in one-third of trials. Nitrogen contained in aboveground cover crop biomass exceeded 60 kg ha–1 in the upper third of trials. Of 30 soil properties measured in each site-year (n = 31) at depths of 0 to 5 and 5 to 15 cm, soil-test biological activity, C mineralization during 24 days, total soil N, and Mehlich-III phosphorus (P) and potassium (K) were most consistently affected when comparing multispecies cover cropping with either no or single-species cover cropping. Despite relatively short duration of evaluations (i.e., mostly one to two years), we were able to elucidate that winter multispecies cover cropping has potential to improve soil health conditions in the region. Soil-test biological activity demonstrated the living nature of soil and was sensitive to conservation agricultural management. The support of a hands-on farmer and adviser network encouraged success.

Multispecies cover crops in organic agricultural systems in the upper U.S. Midwest

AbstractEstablishing cover crops (CCs) in organic systems for the upper Midwest can be a challenge due to shorter growing seasons. The aim of this systems study was to compare CC management implemented in a tilled organic system. The main crops were oat (Avena sativa L.), corn (Zea mays L.), and soybean [Glycine max (L.) Merr.]. Winter hardy (WH) or winter kill (WK) CC mixes were planted after oat, and red clover (Trifolium pratense L.) was planted into oat for the control treatment. The CCs were planted into corn (WH, WK) or after corn harvest (rye [Secale cereale L.], control). Turnip (Brassica rapa L. ssp rapa) were planted after or into soybean (6–17 kg ha–1). Main crop yields were not affected, but CCs performed poorly in corn and soybean for both fall and spring due to dense main crop canopy, dry surface soil, late harvest, and cold fall temperatures. The CC biomass production was greatest following oat because of the longer growing season but still did not establish well as the red clover control needed to be replanted both in 2018 and 2019. Photographic analyses to calculate leaf area index, ground cover, and evapotranspiration revealed few treatment differences throughout the study, which were more likely caused by weather conditions rather than differences in the WH, WK, and control management practices. These findings further demonstrate the difficulties of consistently establishing CC in corn–soybean rotations for the upper Midwest and highlight the need for developing new strategies.

Does Grazing Cover Crops Impact Soil Properties?

Grazing of cover crops (CCs) by cattle could provide supplemental forage and additional revenue to offset grain yield losses when CCs are grown in semiarid rainfed cropping systems. However, grazing CCs could reduce the amount of residue retained on the soil surface and subsequently affect soil physical and chemical properties. This study evaluated effects of grazing CCs on soil bulk density, aggregate stability, and chemical properties using soil samples collected from three producer fields in west central Kansas that had paired grazed and non-grazed CC treatments, as well as adjacent native perennial pastures. Across sites, CC residue after grazing averaged 2650 lb/a compared to 3741 lb/a for the non-grazed CCs, representing a 29% decrease in CC biomass with grazing. Bulk density, aggregate size distribution, and mean weight diameter (MWD) were not different (P > 0.05) between grazed and non-grazed CCs. The MWD under perennial pasture was 0.148 in., approximately 2.9-fold greater than MWD with grazed (0.050 in.) or non-grazed CCs (0.051 in.). Soil pH and soil organic carbon (SOC) did not differ (P > 0.05) between the grazed and non-grazed CCs. Soil nitrate (NO3-N), phosphorus (P), iron (Fe), manganese (Mn), and copper (Cu) concentrations with grazed or non-grazed CCs were greater than in pasture. Our findings showed grazing of CCs may be a management option to intensify NT cropping systems with little negative effects on soil bulk density, aggregate stability, or extractable nutrient concentrations.

Mung bean cover crop improved soil organic carbon and maize yield in a semiarid area

This study aimed to know the potential use of mung bean (Vigna radiata L. Wilzeck) as a cover crop and its effect on soil organic carbon and maize yield were studied. Six cover crop treatments; 250,000, 375,000 and 500,000 plants/ha combined with desiccation times at 28 and 35 days after sowing (DAS) and one control treatment (without cover crop), were tested in a semi-arid area of North Lombok. Maize at a density of 98,000 plants/ha was planted two weeks following the desiccation time. The treatments were arranged in a Randomized Block Design with three replications. The results revealed that the higher cover crop population density with later desiccation time, produced higher above ground biomass, being the highest at 8.3 Mg/ha and the lowest at 2.6 Mg/ha. The highest cover crop biomass improved soil organic carbon by 60%, nitrogen, phosphorous and potash concentrations in plant tissue by 54%, 54% and 63%, respectively, compared to the one in the control treatment. Maize yield also increased by 24% at the highest cover crop density desiccated at 35 DAS. The use of mung bean as a cover crop sounds promising and further studies are needed to explore more of its potential benefits.

Soil phosphorus availability and uptake by mycorrhizal and non-mycorrhizal plants in an onion no-tillage system

ABSTRACT: Onion is an important vegetable crop, predominantly grown under conventional tillage system management. Alternatively, the vegetable no-tillage system uses cover crops to form a residue layer, which improves soil physical, chemical, and biological attributes. Aiming to understand the interaction of mycorrhizal and non-mycorrhizal cover crops, phosphatase activity, and soil phosphorus availability and uptake by plants, a no-tillage vegetable production system experiment with onion was carried out in Ituporanga, Southern Brazil. The treatments were black oats (Avena strigosa); rye (Secale cereale); oilseed radish (Raphanus sativus); rye + oilseed radish; black oats + oilseed radish, and a control with spontaneous plants. Additionally, two plots, a conventional tillage system area and a forest, both adjacent to the experiment, were evaluated. We measured cover crop biomass, onion yield, acid phosphatase activity, and resin-extracted phosphorus in the soil, shoot and root phosphorus content, and root colonization in cover crops, spontaneous plants, and onions. The treatments with cover crops had the highest plant biomass in winter and onion yield. Available soil phosphorus and acid phosphatase activity were higher in no-tillage plots than in the conventional tillage system area. The presence of non-mycorrhizal oilseed radish was associated with decreased colonization of rye and onion roots by arbuscular mycorrhizal fungi. No-tillage areas with cover crops or spontaneous plants in winter accumulated more phosphorus than conventional tillage system areas. The conventional tillage system showed adverse effects on most soil attributes, as shown by a Principal Component Analysis.

Epigeal fauna and soil attributes in a cover-cropped organic vegetable system

ABSTRACT: This study assessed the effect of cover crop biomass on the epigeal fauna of an organic eggplant (Solanum melongena L.) cropping system. A randomized block design was used, with four cover crop treatments: brachiaria, crotalaria, millet, and cocktail (brachiaria, crotalaria and millet). The epigeal faunal indices were determined at each plot. The epigeal fauna of a secondary forest site was also assessed for comparison. Epigeal individuals were collected using pitfall traps at two sampling periods (110 and 180 days after mowing cover crops). Soil samples were collected for determination of physical and chemic properties. 2032 individuals were captured in the first sampling and 3806 individuals in the second. The highest values of wealth in the first collection were observed in the millet and cocktail areas. Cluster analysis showed similarity of epigeal faunal groups between millet and brachiaria plots at the first sampling and between cocktail and crotalaria sites at the second sampling. Co-inertia analysis showed a significant covariance between epigeal fauna at the second sampling and soil properties. The cover crops management had a beneficial influence on the activity, wealth and ecological indexes, in both sampling periods. The positive association observed between epigeal faunal groups and soil physical and chemical properties demonstrates the efficiency of cover crops in improving soil quality in organic cropping systems.