Cover Crop Systems Research Articles

Does a native and introduced cover crop species differ in their ability to suppress weeds? A study in a table grape vineyard

This study compared the weed suppression ability of a native cover crop species phacelia (Phacelia tanacetifolia), an introduced cover crop species rye (Secale cereale L.), and a no cover crop (herbicide‑managed) system in a vineyard. Cover crops were sown in the interrow spaces of the grapevine rows. Percent weed cover after the cover crop termination was lower in the interrow of the phacelia than the no cover crop plots. During the cover crop growing season, phacelia suppressed weeds more than rye. However, the weed seedbank of the cover crop plots was greater than that of the no cover crop plots.

Cover Crop Systems Impact on Biomass Production, Carbon-to-Nitrogen Ratio, Forage Quality, and Soil Health in a Semi-arid Environment

Cover cropping is a soil restorative strategy that can save degraded soils and offer additional benefits relative to the traditional fallow-based practice in semi-arid cropping systems. This study aimed to (i) quantify the above (shoot)- and belowground (root) biomass production, nutritive value, and tissue carbon and nitrogen concentrations from different annual cool-season cover crop systems, and (ii) determine their effects on soil organic carbon, total nitrogen, soil respiration, and soil microbial population biomass in a semi-arid environment. Treatments used were monocultures of annual ryegrass (Lolium multiflorum Lam.), oat (Avena sativa L.), faba bean (Vicia faba L.), yellow sweetclover [Melilotus officinalis (L.) Lam], winter pea (Pisum sativum L.), two three-species mixtures (Mix 1: annual ryegrass + faba bean + yellow sweetclover and Mix 2: Oat + faba bean + winter pea), and a fallow laid out in a randomized complete block design with three replications. Averaged across years, Mix 2 produced greater shoot biomass (9714 kg DM ha-1; SE = 699) than all other cover crop systems except, the monoculture of oat (7970 kg DM ha-1; SE = 699). The plant tissue C/N ratio of the mixtures and monoculture legumes was mostly similar (range = 19.4 – 29.1). Overall, legumes produced superior relative feed value (RFV; 112 – 161) compared to grass monocultures and mixtures (RFV; 80 – 95). Soil gram-negative bacteria biomass was greatest under the yellow sweetclover monoculture. Based on the results of this study, the mixed cover crop systems (Mix 1 and Mix 2) offered a better chance of fulfilling the dual role of soil health improvement and feed quality for livestock in this semi-arid environment.

Quantifying the spatial heterogeneity of topsoil microstructure in a horticultural cover cropping system from Southwestern Ontario, Canada

Cover crops (CC) are promoted to enhance soil structure and aggregation, but little is known about their impact on the spatial variability of soil microstructure. This study was conducted to assess the effects of medium-term (4-yr) annual CC systems, including oat (Avena sativa L.), winter cereal rye (rye; Secale cereale L.), oilseed radish (OSR; Raphanus sativus L. var. oleoferus Metzg. Stokes), as well as a mixture of OSR and winter cereal rye (OSR + Rye), against a control (no cover crop, no-CC), on topsoil microstructure utilizing 3D semivariance analysis, as influenced by soil depth (0–5 and 5–10 cm) in a tile-drained Orthic Humic Gleysol in Ridgetown, Ontario, Canada. Replicate undisturbed topsoil core samples were collected manually in plexiglass tubes from each plot. All soil cores were dried at 40 °C, then imaged at 20 μm pixel size using GE MS8-130× CT scanner (120kv, 0.5 mm Cu filter). The whole core greyscale imagery (representing radiodensity on the Hounsfield Scale) was subjected to a three-phase segmentation (solids, voids, and remaining soil matrix). For the whole soil and the soil matrix imagery, 16-bit histograms and 3D orthogonal semivariograms were generated. Directional anisotropy and four semivariogram parameters close to the origin, including the ratio between the values of the total variance and the semivariance at first lag (RVF), the ratio between semivariance values at second and first lag (RSF), first derivative near the origin (FDO), and second derivative at the third lag (SDT), were calculated to explain spatial variability in the soil microstructure. The results exhibited lower radiodensities for whole soil samples from the 0–5 cm than 5–10 cm layers. All CCs, other than oats, showed lower radiodensities than the control (no-CC). For both the whole soil and soil matrix, more variability was encountered in the vertical than the horizontal dimensions of all soils. Comparing the whole soil and the soil matrix in different CC systems and layers, more anisotropy was pronounced in the soil matrix than the whole soil imagery. The highest and the lowest anisotropy, calculated for the whole soil and soil matrix of different CC systems, were observed in oat and rye plots, respectively. There were no significant differences among CCs systems in terms of RVF, RSF, and SDT values, suggesting similarity of the structure at the scale slightly above image resolution. The results illustrated that soils under different CC systems showed only significant differences in the whole soil for FDO values (P ≤ 0.08). All four near-origin semivariogram parameters showed significant differences between 0 and 5 and 5–10 cm layers in both the whole soil and the soil matrix, suggesting more complexity in the microstructure of the uppermost soil layers.

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

Simple rotation systems as wheat (Triticum aestivum L.)-fallow practiced in semi-arid regions are currently being transformed by replacing fallow with winter pea (Pisum sativum L.). However, there is insufficient understanding of how such diversification of plant functional groups impacts the biological and chemical soil properties which drive ecosystem services. This study investigated how diversifying rotation system coupled with nitrogen (N) fertilization impacts the diversity and activity of microbial communities and other essential soil properties such as soil organic carbon (C). Soils from a long-term field experiment (Pendleton, OR, USA) were sampled in 2021 at two depths (0–5 cm and 5–10 cm) and characterized for microbial biomass carbon (MBC), prokaryote community composition and diversity (16 S amplicon sequencing), activities of enzymes involved in C, N, phosphorous (P) and sulfur (S) cycles and soil chemical properties. The results indicated that MBC and enzyme activity were greater in the wheat-pea rotation compared to wheat-fallow, while fertilization was not a significant factor for these properties. Enzyme activities normalized by MBC showed fewer differences suggesting that the impact is mostly due to differences in MBC. Replacing fallow with pea decreased alpha diversity metrics at both depths and for both the highest and the lowest level of taxonomic hierarchy, although the effects upon phyla richness were not statistically significant. Nitrogen fertilizer decreased the Shannon index and Shannon evenness, especially in the 5–10 cm depth. While communities at the amplicon sequence variant (ASV) level were clearly separated by the rotation system, they were less separated by fertilization which distinguished communities only in the wheat-fallow system. Redundancy analysis (RDA) followed by variance partitioning analysis (VPA) indicated that soil properties explained most of the variation in the community structure at the phylum level with rotation and fertilization having no unique contribution. This suggests that the effects of rotation and fertilization are mediated through the changes these practices induce upon other soil properties. Overall, the results show that changing wheat-fallow into wheat-pea cover crop systems increases some soil health indicators while decreasing diversity which suggests that no direct coupling exists between above and belowground biodiversity.

Soil Microbial Biomass and Bacterial Diversity Enhanced through Fallow Cover Cropping in Rice–Fish Coculture

Traditional rice production is often reliant on the unsustainable practice of utilizing intensive inputs in monoculture cropping systems. Alternatives fallow cover cropping and rice–fish coculture (RFC) offer promising solutions. However, the potential of fallow cover cropping in RFC remains underexplored, and its impact on soil microbes is poorly understood. In this study, assessments of soil–plant–microbe interactions were conducted across three cover cropping systems: Chinese milk vetch (Astragalus sinicus L.) single cropping (CM), Rapeseed (Brassica napus L.) single cropping (RP), and a combination of Chinese milk vetch and rapeseed intercropping (CM_RP). These systems were evaluated with and without nitrogen (N) addition, encompassing both the RFC and rice monoculture (RMC) systems. The findings indicate a notable increase in soil microbial biomass nitrogen (MBN) with CM. Soil microbial biomass carbon (MBC), influenced more by N-fertilizer than crop species, decreased with N addition. In the RFC system, the soil bacterial co-occurrence network exhibited more connections, yet negative links increased. CM_RP displayed similarities to CM without N but shifted closer to RP with N addition. N addition in intercropping significantly increased the root–shoot ratio (R/S) of A. sinicus, associated with decreased aboveground biomass and total root length. Compared to RMC, RFC with N addition reduced the relative abundance of Anaerolineaceae in CM while increasing Bacillus and Pontibacter across cover cropping systems. Overall, with N addition, both RFC and RMC showed decreased soil bacterial diversity indices. Changes in soil bacterial diversity correlated significantly with soil MBC, MBN, and plant R/S. Continuous fallow cover cropping altered soil microbial biomass and affected cover crop biomass distribution, impacting bacterial composition in paddy soil. These results shed light on how bacterial communities respond to N addition and fallow cover cropping in RFC and RMC systems, offering insights for sustainable nutrient management in paddy systems.

Plant diversity as a sustainable strategy for mitigating biotic and abiotic stresses in tomato cultivation

Sustainable agriculture has become a global priority in response to increasing food demand and the challenges confronting agricultural production, such as biotic and abiotic stresses. In this review, we delve into the role of plant diversity in mitigating these stressors within tomato cultivation. Our investigation reveals that the most extensively studied companion species are Vicia villosa Roth, Coriandrum sativum L., and Allium cepa L., while the primary stressors under scrutiny include nutrient deficiencies, aerial pests, and soil-borne pathogenic diseases. Regarding nutrient deficiencies, the cover crop system has demonstrated its capacity to provide essential nutrients directly and indirectly to plants. In addressing aerial pests and pathogens, all cultivation systems exhibit contributions. Finally, we assert that incorporating plant diversity into agroecosystems can effectively counteract various types of stressors. These benefits align with the application of agroecological principles and the development of sustainable agroecosystems. Further assessments of the effects of additional companion plant species are imperative. This should encompass the identification of their distribution, optimal plant quantities, and cultivation systems that enhance their benefits. Ultimately, these evaluations will aid in the formulation of comprehensive guidelines to facilitate the selection and utilization of plant diversity for long-term sustainability.

Tillage and Cover Crop Systems Alter Soil Particle Size Distribution in Raised-Bed-and-Furrow Row-Crop Agroecosystems

Conservation alternatives that include no-tillage (NT) and cover crops (CCs) reduce soil erosion in row-crop agroecosystems. However, little information is available about how these alternatives affect soil textural properties responsible for soil fertility. This study evaluated the soil particle size distribution and volumetric water content after three years of consistent management in a raised bed system. There were four treatment systems in a dryland maize/soybean rotation on a silt loam soil (Oxyaquic Fraglossudalfs) that included: NT + CCs, conventional tillage (CT) + CCs, CT + winter weeds, and CT + bare soil in winter in northwest Mississippi. The NT + CC system retained 62% more coarse sand in the furrow than the other systems (2.1% compared to 1.3%; p = 0.02). Regardless of the location, the NT + CC system (2.5%) retained 39% more fine sand than the CT + CC system (1.8%; p = 0.01), suggesting that coarse and fine sands were being trapped in furrows combining NT + CC systems, minimizing their off-site transport. In furrows, CCs increased soil volumetric water content by 47% compared to other winter covers. In beds, NT + CCs increased bed water contents by 20% compared to CT + CCs (17.1 to 14.3%; p < 0.01). Implementing conservation alternatives may promote the retention of sand fractions in silty loam soils that are important in supporting soil fertility and crop sustainability.

Maize Yield and Soil Penetration Resistance in Different Soil Tillage and Cover Crop Systems

Maize Yield and Soil Penetration Resistance in Different Soil Tillage and Cover Crop Systems

Addition of biochar decreased soil respiration in a permanent no-till cover crop system for organic soybean production

The increase in soil carbon sequestration under long-term no-till (NT) and cover crop management has been shown to form part of a sustainable agricultural management practice system. Along with the increase in soil organic carbon (SOC), soil respiration in this system was also enhanced by the increased soil temperature through the decomposition that causes carbon loss from the soil. To overcome this issue, biochar can be applied. However, the addition of biochar into this system is not well studied. Therefore, the aim of this study was to investigate the effect of this system on soil respiration. The experiment was conducted at the Center for International Field Agriculture Research & Education, Ibaraki University. Long-term tillage practices, such as NT and moldboard plowing (MP), cover crops such as rye (RY) and fallow (FA), and biochar application such as with biochar (WB) and no biochar (NB) were applied to a split–split plot in a randomized complete block design with four replications. The daily CO2 flux was measured every week at 9:00–11:00 a.m. The daily soil respiration was affected by tillage and cover crop with NT practice had significantly higher daily CO2 flux than that of MP (23.8%–107.4% and 38.0%–107.8%), while RY had higher flux than that of FA (11.9%–81.2% and 34.9%–65.4%) in 2020 and 2021 soybean growing season, respectively. Additionally, in the 2020 cover crop growing season RY also increased daily CO2 flux approximately 41.8%–88.2% compared to FA. Biochar addition significantly reduced soil respiration in soybean and cover crop seasons compared to NB by 24.0%–50.7% and by 25.9%–48.3%, respectively. This reduction in soil respiration by the biochar decreased annual CO2 emissions by 17.6% and 13.0% in 2020 and 2021. The values of these emissions ranged from 9.6 Mg ha−1 for MP FA WB to 18.9 Mg ha−1 for MP RY NB in 2020 and from 7.5 Mg ha−1 for MP FA WB to 13.7 Mg ha−1 for NT FA NB in 2021. This study highlights the crucial role of biochar in reducing soil respiration and enhancing SOC sequestration. The addition of biochar into this system was able to reduce soil respiration by regulating the soil temperature, soil moisture, and protect the SOC from decomposition. Biochar addition also increased the SOC and decreased the soil bulk density, which improves soil porosity. Therefore, these findings would be very useful to be included within the global scenario of soil organic matter management.

Effect of Aluminum Sulfate and Cover Crops on Some Chemical and Physical Properties of Degraded Soil

Prevalence of saline and sodic soils has been increased in arid and semi-arid regions which are often depend on irrigated agriculture, and this has led to a major threat to the agricultural sustainable production and environment. An alum has been used as chemical amendments in reclamation of degraded and dispersive soils which are affected by higher sodium concentration. A field experiment was carried out during the fall season in July, 2022 at Karma District - Anbar Governorate to study the effects of aluminum sulfate (alum) and cover crops on some soil physical and chemical properties and crop indicators in silty clay degraded soil due to salinization and high sodicity. The experimental design for the study site was a split-plot design arrangement with a randomized completely plot design (RCBD. The whole plot factor included cover crops which included no cover crops (NCC), sesbania (CC1) and millet crop (Panicum miliceum L.) (CC2), and alum levels were a split-plot factor which included A0 (0 mg ha-1), A1 (1.8 mg ha-1), A2 (3.6 mg ha-1) and A3 (7.2 mg ha-1). Three replications within each treatment were used in this study design, and the total experimental treatments were 36 treatments. Sorghum was planted as main crop in this study. The results showed that the concentration of A3 has decreased adsorption sodium percentage (ESP), pH, soil bulk density and carbonate minerals by 64, 20, 21 and 35%, respectively as compared with A0. Also, the alum level of A3 had greater aggregate stability, total porosity and saturated hydraulic conductivity (Ksat) by 100, 29 and 145%, respectively. Cover crops were roughly decreased by 10, 3 and 8% for ESP, soil bulk density and carbonate minerals, respectively. The water-stable aggregates and Kat were increased by averaging 8-12% and averaging 8-29 mm hr-1, respectively for cover crop systems as compared to NCC management. The treatment of CC2A3 had the highest values for all measured soil properties as compared with the control treatment of NCCA0. In conclusion, adding alum and planting cover crops have been contributed to improved overall soil chemical and physical properties in degraded soil.

Comparative analysis of rhizobial and bacterial communities in experimental cotton fields: Impacts of conventional and conservation soil management in the Texas High Plains

Conservative agricultural management strategies pursue long-term ecological benefits through practices such as no-tillage, cover crop, and inherent soil properties management. Farmers, however, are often hesitant to adopt such practices due to lack of experience, initial expense, and concern for low crop productivity. Overcoming this barrier requires novel approaches, such as effectively managing the soil microbiome to attain high productivity at a low cost, especially in a semi-arid region. To study the potential of conservation agriculture, we investigated components of soil bacterial community and rhizobial diversity in long-term experimental cotton fields divided into conventional tillage monoculture systems with winter fallow (CT) and no-tillage with mixed cover crop (M-NT) system on the Texas High Plain (THP). We conducted next-generation amplicon sequencing targeting rpoB gene with collected soil samples from different soil managements and seasons. Our research revealed that although CT had significantly greater bacterial diversity and species richness than the M-NT management, rhizobial diversity and species richness were higher in M-NT than in CT management. Both bacterial and rhizobial diversity and richness were greater in summer than in fall. The abundance of the order Rhizobiales was consistently high in M-NT than in CT fields in both seasons. Soil management altered the dominant rhizobial genus associated with cotton production systems; Rhizobium and Pararhizobium dominated M-NT management, while Bradyrhizobium and Sinorhizobium were dominant under CT management. These outcomes suggest that incorporating legumes into a cover crop in this semi-arid cotton-growing region can initiate beneficial changes to the dynamics of the indigenous rhizobial assemblage. The high prediction accuracy of our machine learning model using bacterial community data classifying the managements as CT or M-NT validates the possibilities of a strong underlying relationship between soil management and the bacterial diversity in the soil.

A perennial living mulch system fosters a more diverse and balanced soil bacterial community.

Cover crops are known to positively impact soil health, both at a physical level (through erosion control and organic matter enhancement) and at a biological level (by fostering more diverse microbial communities). However, most research in this area has been conducted in the context of annual cover crops that are terminated when the main crop is planted. We have previously demonstrated that a continuous "living mulch" cover crop system can enhance the physical and chemical aspects of soil health; In this study, we reveal its effect on the soil bacterial community and compare it to two different annual cover crops and a conventional control without cover crops. We examined the effect of a living-mulch (LM) system using perennial white clover (Trifolium pratense L), annual cereal rye (Secale cereale L.) (CR), annual crimson clover (Trifolium incarnatum L.) (CC), and a no-cover (NC) control at three time points during the 2018 growing season. 16S rRNA amplicon analysis of the soil bacterial community revealed that the community composition in cover crop systems was significantly different from the NC control, and that LM and CR accommodated more heterogeneous and even bacterial communities compared to the NC control. The difference in bacterial composition between cover crop systems appears to be partly influenced by soil nitrogen concentration and lime buffer capacity. Overall community diversity was associated with nitrogen and metal ion concentrations, and these associations were both stronger and more numerous later in the season. These results elucidate how a perennial cover crop system affects the soil bacterial community and advance our understanding of the interactions between crops, management practices, and soil microbiomes in sustainable agriculture.

No-tillage and rye cover crop systems improve soil water retention by increasing soil organic carbon in Andosols under humid subtropical climate

No-tillage (NT) combined with a cover crop is a climate-smart agricultural practice that eliminates nearly all physical disturbance of the soil surface and increases soil aggregation and soil organic carbon (SOC); however, the response of SOC and soil water retention (SWR) to long-term NT and cover crops systems in the volcanic ash Andosol soil of Japan has not been well addressed. This study aimed to evaluate the effect of NT and moldboard plow (MP) tillage systems combined with rye (RY) and fallow (FA) cover crop treatments on SOC, active carbon (AC), water-stable aggregates, aggregate stability index, mean weight diameter (MWD), bulk density, aggregate-associated carbon, and SWR. NT significantly increased the > 4 and 2 mm aggregates, aggregate-associated C at the 0–2.5 and 2.5–5 cm depths, field capacity, and SWR between 0 and 15 cm. RY cover crops significantly increased aggregate-associated carbon at the 2.5–5 and 5–10 cm depths in both NT and MP and SWR at the 10–15 cm depth. NT combined with RY significantly increased SOC and AC in the surface layer and volumetric water content at all soil depths. Path analysis revealed that SOC and MWD were correlated with easily plant-available water (EPAW) and field capacity under the NT system and is the primary reason for the observed increase in SWR. Thus, the NT system increased plant residue, reduced soil evaporation, increased SOC content and SWR, and bonded soil microaggregates into macroaggregates better than the MP system. The use of an RY-based NT system is an effective climate-smart agriculture practice that reduces the drought effects brought on by climate change.

Residual biomass quality index: a tool for conservation agriculture

ABSTRACTOne of the pillars of a no-tillage system is the addition of adequate amounts of residue to keep the soil continuously covered. Cover crops are a tool for supplying the demand for the permanence of residues on the soil surface and releasing nutrients to the soil. However, there is no index that relates these two factors and can reconcile the maximum permanence of crop residues in the soil with the maximum N supply via N mineralization of such residues. This study aimed to assess the effect of different cover crops on the decomposition rate of residues and N release, using the residual biomass quality index (RBQI) to evaluate cover crop systems. The study was conducted in a long-term experiment in a Latossolo Vermelho (Ferralsol, Oxisol) under no-tillage in the two agricultural years 2017/18 and 2018/19. The experiment was in a split-plot factorial scheme with eight winter cover crops and three N rates in randomized blocks with three replications. The cover crop systems were black oat (O), common vetch (V), forage radish (R), white lupine, rye, annual ryegrass, oat + vetch (O+V), and oat + vetch + radish (O+V+R). The N rates applied to the corn in succession were 0, 90, and 180 kg ha-1. The decomposition rate, remaining dry mass (RDM) on the soil surface, N release rate, and N accumulated release (NAR) were assessed using litterbags. Considering NAR and RDM evaluated for up to 105 days, the N release index (NRI) and remaining dry mass index (RDMI) were determined, and the residual biomass quality index (RBQI) was obtained using the product of these variables. The consortia O+V+R and O+V resulted in a decomposition rate and N release rate closer to the rates observed for oats and rye. The NAR was similar to that observed for Fabaceae species, and the RDM was similar or superior to that found for black oat. With these characteristics, the systems in the O+V+R and O+V consortia presented the highest values of RBQI, ranging from 0.61 to 0.90, indicating that RBQI is a potential indicator for choosing cover crop systems that promote greater sustainability of the no-tillage system. The use of N fertilizer in corn did not change the rates of decomposition and N release from the residues of cover crops.

ANALYSIS OF CONSTRAINING FACTORS REGARDING ADOPTION OF SOIL AND WATER CONSERVATION PRACTICES IN THE POTHOHAR, PUNJAB

The current study was conducted at Institute of Agri. Extension, Education and Rural Development, University of Agriculture, Faisalabad in 2022. Rawalpindi district was selected purposively as it receives maximum rainfall. Four out of seven tehsils of Rawalpindi were selected purposively based on maximum numbers of farmers. A sample size of 381 respondents was drawn using surveysystem.com. Proportionate sampling technique was used to interview 214, 104, 32 and 31 farmers from tehsil Gujar Khan, Rawalpindi, Kotli Satiyan and Kahuta respectively. Mix methods research design was used to conduct the study. Quantitative and qualitative data were collected using well-structured interview schedule and a comprehensive interview guide respectively. Research findings revealed that awareness and adoption level of farmers regarding various soil and water conservation practices was unsatisfactory. High level adoption gap was found regarding different soil and water conservation practices: crop rotation (92.4%), intercropping (99.7%), cover cropping (99.8%), terracing (96.1%), broad bed and furrow system of land configuration (96.6%), sowing drought resistant varieties (86.3%), contour farming (85%) and mulching (97.9%). It was concluded that farmers were not only deprived of the advisory services but also the required trainings and technical assistance regarding adoption of conservation measures. Therefore, provision of trainings and demonstration facilities were strongly recommended to educate the farmers regarding basic soil and water conservation measures. Moreover, farmers should also be provided with financial assistance in form of subsidized input supply.

Soil organic carbon fractions in response to soil, environmental and agronomic factors under cover cropping systems: A global meta-analysis

Cover crops may improve soil health and increase soil carbon sequestration, thus contributing to both the adaptation to and mitigation of climate change. Despite these potential benefits, there currently lacks a global synthesis of the impacts of cover crops on soil organic carbon (SOC) fractions. We conducted a global meta-analysis of 93 peer-reviewed studies to quantify the effect of cover crops on changes in SOC fractions and the influence of environmental and management factors. Compared to bare soil management, cover crops increased SOC by 12% and increased seven SOC fractions, including microbial biomass carbon (MBC) by 33%, dissolved organic carbon (DOC) by 18%, particulate organic carbon (POC) by 15%, light-fraction organic carbon (LFOC) by 14%, permanganate oxidizable carbon (POXC) by 13%, short-term mineralizable carbon (SMC) by 10%, and mineral-associated organic carbon (MAOC) by 7%. The effect size of SOC was positively correlated with the effect sizes of MBC, POC, LFOC, and MAOC, but negatively correlated with the effect size of DOC. Soil taxonomic order and experimental duration were key factors affecting the beneficial effect of cover crops on the SOC fractions. Greater increases in SOC fractions due to cover crops were found in Entisols and Ultisols in comparison with other soil orders. The effect size of MAOC increased with experimental duration. Our study suggests that cover crops can significantly increase various SOC fractions, which likely serves as a building block for SOC sequestration and improvement of many aspects of soil health.

Cover crop and biofuel crop effects on hydraulic properties for claypan soils

AbstractPerennial biofuel and cover crops systems are important for enhancing soil health and can provide numerous soil, agricultural, and environmental benefits. The study objective was to investigate the effects of cover crops and biofuel crops on soil hydraulic properties relative to traditional management for claypan soils. The study site included selected management practices: cover crop (CC) and no cover crop (NC) with corn/soybean rotation, switchgrass (SW), and miscanthus (MI). The CC mixture consisted of cereal rye, hairy vetch, and Austrian winter pea. The research site was located at Bradford Research Center in Missouri, USA, and was implemented on a Mexico silt loam. Intact soil cores (76‐mm diam. by 76‐mm long) were taken from the 0–10, 10–20, 20–30, and 30–40 cm depths with three plot replicates and two sub‐samples per plot replicate per depth. Soil hydraulic properties evaluated for each sample included: saturated hydraulic conductivity (Ksat), water retention, bulk density, and pore size distributions. Results showed with the test of Duncan's least significant differences that treatments of MI (1.18 Mg m−3) and SW (1.21 Mg m−3) had lower values of bulk density averaging across soil depth than CC (1.27 Mg m−3) and NC (1.31 Mg m−3). Management systems significantly increased Ksat with the biofuel treatments at 0–10 cm compared to NC system. The MI management showed a significant increase in macroporosity and fine mesoporosity as compared to other management systems. Slight changes have occurred in the measured soil physical properties for CC system compared to NC plots. Overall, increasing soil organic matter from more plant roots from long‐term biofuel cropping systems can improve soil water storage and crop productivity.

117 Effects of Cattle Removal Date on Sustainability of Cool-Season Annual Grazed Cover Crop Systems

Abstract Grazing of cool-season cover crops has been shown to be a viable tool in extending the grazing season while mitigating environmental risks associated with row crop farming systems. While there is a vast amount of research available on cover crops in relation to soil health, a more novel approach would be to focus on forage production and animal performance when grazing cover crops. Therefore, our objective was to evaluate the effects of cattle removal date on forage yield, forage quality, and steer performance when grazing cool-season cover crops. A cool-season forage mix consisting of ‘Cosaque’ oats (Avena strigose), ‘FL401’ cereal rye (Secale cereal), ‘AU Sunrise’ crimson clover (Trifolium incarnatum), and ‘T-raptor’ brassica (Brassica napus × B. rapa) was established in twelve, 0.62 ha paddocks in Headland, AL. Each paddock was then randomly allocated to one of four cattle removal treatments: 1) no grazing (CON); 2) February removal (FEB); 3) March removal (MAR); or 4) April removal (APR). Three tester steers were randomly allotted, based on body weight (BW), to each of the grazing treatments, excluding CON. The tester steers were weighed every 30 d for calculation of initial BW, final BW, and average daily gain (ADG). At inception and every subsequent two weeks, forage was harvested to analyze average forage yield, neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude protein (CP). All data were analyzed using GLIMMIX procedure of SAS version 9.4 (SAS Inst., Cary, NC). Significant differences in forage yield were detected between CON and FEB (3,913 vs. 2,261 kg/ha; P < 0.001), CON and MAR (3,913 vs. 1,790 kg/ha; P < 0.001), and CON and APR (3,913 vs. 1,810 kg/ha; P < 0.001). There were no differences found for ADG (1.2 kg/day; P = 0.56), NDF (50.94%; P = 0.46), or ADF (30.34%; P = 0.25) among treatments. Results indicate that grazing of cool-season annual cover crops will reduce forage yield, but removal date of cattle will not further affect forage yield, quality, or individual cattle performance. Thus, we can reduce winter supplementation needs for cattle by increasing grazing days; however, under continuous grazing for stocker cattle production, forage availability may inevitably be the limiting factor.

Assessing the Efficacy of Living and Dead Cover Crop Mixtures for Weed Suppression in Sweet Corn

Modern vegetable production systems are often characterized by monoculture fields and the intensive use of tillage and/or synthetic agrochemicals for managing weeds. A growing public interest in more sustainable and eco-friendly production practices has resulted in increased demand for crops to be produced with lower inputs. Field studies were conducted over three field seasons to investigate the use of conservation tillage in concert with an interplanted living mulch and/or cover crop residue for managing weeds in sweet corn as compared with the standard practice of using conventional tillage and pre-emergence residual herbicides. Whole plot treatments included: (1) conventional till, (2) no-till with cover crop residue, (3) living mulch + cover crop residue, and (4) living mulch + winter killed residue. The split-plot factor consisted of herbicide treatments: (1) at-planting application of residual herbicides or (2) no herbicide. The cover crop systems suppressed weeds as well as the standard practice throughout the cropping cycle in all three years. In addition, there was no significant improvement in weed suppression with the application of herbicides within the cover crop treatments. Crop development and yield were similar among treatments in year 2. However, reduced yields were encountered in all cover crop treatments during year 3 relative to the conventional tillage treatment.

Deep SOC stock dynamics under contrasting management systems: Is the EPIC model ready for carbon farming implementation?

Process-based models have been recognized as cost-effective tools to assess carbon farming mechanisms through quantifying the C fluxes in the agroecosystems. A result-based approach is suggested however the wide variability of agricultural environments makes further model implementation necessary to limit the uncertainty of the results, especially on deep soil organic carbon (SOC) stock estimation and stratification and in agroecosystems characterized by a shallow water table. In this study, a comprehensive soil and crop dataset collected over a seven-year period from different pedoclimatic conditions across the Veneto Region (NE Italy) was used for EPIC model calibration and validation of SOC stock dynamics. Experimental data included yields from several crops (corn, winter and spring wheat, rapeseed, and soybean), continuous monitoring of soil water content, and SOC stocks (1872 total samples within the 0–50 cm soil profile) under conventional, cover crop and conservation agriculture systems. Modelling was performed by testing two N-C sub-models (CENTURY and PHOENIX), which differentiated in terms of mineralization/immobilization rates.Results showed that the procedure was able to obtain parameters valuable for most of the management system and pedoclimatic condition, reproducing well the tested variables. The EPIC model acceptably captured soil water dynamics (Nash-Sutcliffe coefficient – NSE – was up to 0.26), especially in the topsoil. Furthermore, simulation of weed—crop competition in conservation agriculture strongly contributed to properly explain the variability in crop production among the contrasting agricultural systems (R2 ranged from 0.51 to 0.71). Likewise, EPIC skillfully simulated SOC stocks within the 0–50-cm profile regardless of the sub-model used (NSE was up to 0.64). Moreover, the model acceptably captured the profile SOC stratification among the different management practices. This study highlights the EPIC robustness for predicting SOC stocks and assessing with high accuracy carbon farming results.