Cover Crops Research Articles

Cover crop mixtures do not assemble markedly distinct soil microbiotas as compared to monocultures in a multilocation field experiment

Cover crops are used in cropping systems to enhance ecosystem services, such as soil resilience to erosion or microbial activity. Different cover crops are selected to steer specific processes, but whether cover crop mixtures have an added value over monocultures remains debated. Here, we investigated if cover crop mixtures accumulate soil microbiotas distinct from those of monocultures, potentially leading to more varied microbially-driven soil functions. We performed a field experiment at three locations in the Netherlands, each including nine cover crop monocultures, five- and eight-species mixtures, and a fallow control. After three months, we measured cover crop biomass and profiled soil bacterial, fungal, and arbuscular mycorrhizal fungal communities via amplicon sequencing. The different crop monocultures produced similar biomass across all three locations, and mixtures had average productivity compared to monocultures. The diversity and community structure of soil microbial communities was primarily determined by the geographical location, and then by cover crop treatment at each location. Although the cover crop species affected the soil microbiome differently, cover crop mixtures did neither increase microbial diversity nor the overall community differentiation compared to monocultures. Our results suggest that mixing cover crop species does not significantly influence microbially-driven soil functions, at least in short-term crop rotations.

Host status of cover crops for the management of Meloidogyne izalcoensis in coffee orchards infested with root-knot nematodes

Summary The root-knot nematode Meloidogyne izalcoensis was described parasitising coffee trees and causing damage in the Izalco volcano region, Sonsonate, El Salvador. In Brazil, it was detected in coffee roots in the municipality of Indianópolis, Minas Gerais state (MG). Intercropping cover crops is a traditional practice in Brazilian coffee orchards, and the use of plants that are non-hosts or antagonistic to the nematodes is a very promising strategy for coffee in infested areas. Due to the scarce information on the host status of M. izalcoensis, the aim of this study was to evaluate 24 plants of different species of cover crops and select the non-hosts or poor hosts. Two assays were conducted at different times, and all plants were inoculated with 10 000 eggs. After 90 days, the following parameters were determined: fresh root weight, reproduction factor (RF) and final reaction. Plants with RF < 1.0 were classified as non-hosts (NH), those with RF > 1.0 were classified as hosts and using statistical analyses as: good host (GH), intermediate host (IH) and poor host (PH). Most of the botanical species tested were classified as NH or PH to M. izalcoensis: cotton, rice, white oat, black oat, ryegrass, corn, three species of grass, two cultivars of millet, two wheat cultivars, Crotalaria breviflora, C. ochroleuca, C. spectabilis, jack bean, gray mucuna bean and two species of rice grass. Only tomato and bean were classified as GH, and C. juncea and soybean were classified as IH. The plants identified as non-hosts or poor hosts can be recommended for intercropping or for crop rotation in Brazilian coffee orchards in regions infested by M. izalcoensis.

Nitrogen transformation as affected by decomposition of 15N‐labeled cover crop shoots and roots

AbstractBackgroundIncorporation of cover crop (cc) shoot and root biomass can have different effects on nitrogen (N) dynamics and the transformation of soil‐derived N and cc N.AimsThe objective was to determine the effects of different ccs, cc compartments (roots and shoots), and pretreatment of cc biomass (fresh vs. dried) on mineralization processes and on the transformation of soil and cc N following incorporation into a silty loam soil.MethodsSoil columns with incorporated 15N‐labeled root and shoot biomass of two cc species (winter rye and oil radish) and different pretreatments (dried and fresh) were incubated for 70 days at a constant temperature and soil moisture (8°C, 40% water‐filled pore space). Carbon and N transformation dynamics were determined repeatedly, distinguishing between N originating from cc biomass and from soil.ResultsNet CO2 emission was related to the amount of soluble cell components added with ccs. Net N mineralization was negatively related to the C:N ratio of cc biomass. The incorporation of dried cc biomass caused higher initial soil respiration and N immobilization than fresh biomass. All treatments with cc incorporation showed increased N2O emission. Emitted N2O‐N consisted mainly of cc N (55%–57%) in treatments with fresh shoot biomass, whereas soil N was the main source of N2O (75%) in the treatment with fresh oil radish roots. Recovery of cc 15N was affected by crop compartment and pretreatment. At the end of the incubation, it was 17.5%–42.3% in soil NO3−, 0.1%–8.1% in microbial biomass N, and less than 0.23% of cc N was found in cumulative N2O emission.ConclusionThe incorporation of cc roots and shoots had different effects on N mobilization and immobilization processes and on the partitioning of cc N. These processes can be influenced significantly by pretreatment of the added plant biomass (dried vs. fresh).

The response of a sorghum sudangrass cover crop to residual nitrogen and its relationship with spectral sensors

AbstractA sorghum sudangrass (SSG) cover crop grown after a cash crop could take up residual nitrogen (N) before it is lost. As in‐field monitoring of SSG properties is laborious, predicting biomass and N concentrations with spectral sensors could be useful. At two sites in Live Oak, Florida, we evaluated the response of SSG to residual N from previous N fertilization and the performance of handheld and satellite sensors in estimating SSG properties. We quantified aboveground biomass, plant N, leaf greenness (NDVI), net potential N mineralization (PNM), and soil permanganate oxidizable carbon (POXC). Residual N did not affect SSG properties, PNM was highest at the highest N input rate in one site, and soil POXC was correlated with SSG properties (biomass and plant N). NDVI measured from a handheld sensor better predicted SSG properties than satellite imagery in these small plots, suggesting a greater potential to be a useful management tool.

Winter cover crops and irrigation alter soil microbial community composition in an arid cropping system

Cover cropping is a well-established strategy to improve soil health, especially in arid and semi-arid agricultural systems. Benefits to soil health are often mediated via effects of cover crops on soil microbial community structure, function and diversity, crucial for regulating soil biogeochemical cycles, eventually promoting agricultural sustainability. However, limited water availability is a major constraint for both cover crop growth and soil microbial activity. This study sought to characterize and elucidate the shifts in soil microbial community structure in response to different cover crops and differential irrigation treatments using phospholipid fatty acid (PLFA) profiling in southern New Mexico. We tested five cover crop treatments: Pisum sativum (Australian winter pea), Hordeum vulgare cv. Stockford (barley), Brassica juncea cv. Caliente 199 (brown mustard), a three-way mix, and a fallow control — in combination with irrigation treatments of one, two, or three irrigation applications — in a split-plot design over two years. Zea mays (sweet corn) was grown as the summer cash crop. We collected soil samples just after cover crop planting in the fall of 2018, following second year cover crop termination but during Z. mays growth in June 2020, and after the second season of Z. mays growth in October 2020. Differential irrigation treatments did not lead to consistent patterns of change under any cover crop or irrigation treatment. However, PLFA parameters in cover cropped compared to winter fallow plots tended to decrease under one and three irrigations but increased with two irrigations. Changes were more common for bacterial than for fungal PLFA biomarkers, and more common in B. juncea and H. vulgare cover crops than in P. sativa or the mix. It is important to note that, while cover crop effects were inconsistent, cover cropping did lead to some shifts in PLFA biomarkers, even in the short two-year period of cover cropping.

Assessing and Quantifying the Carbon, Nitrogen, and Enzyme Dynamics Effects of Inter-row Cover Cropping on Soils and Apple Tree Development in Orchards

Cover crops between rows in orchards can improve the development of soil resources and increase agricultural productivity. However, there have been few reports of cover crops that can act as a “green manure” in apple orchards across arid and semiarid zones. This study investigated the effects of planting interrow vegetation on soil properties and apple tree performance during a 32-month experiment. There were six treatments: clean cultivation as a control; natural grass planting; planting with ryegrass; planting with alfalfa; planting with tall fescue; and planting with villous wild pea cover crops. The treatments primarily affected the 0- to 20-cm surface soil layer. Soil carbon, nitrogen, and enzyme levels initially decreased (during the first 12–24 months); then, they increased (24–32 months). The cover crops significantly increased nutrient contents (soluble organic carbon, microbial carbon and nitrogen, alkaline dissolved nitrogen, nitrate nitrogen, and ammonium nitrogen) in the 0- to 20-cm soil layer by more than 19.6% and increased the related enzyme activities by more than 25.2%. The alfalfa and wild pea alleys had a stronger effect on the soil environment than the control, natural grass, ryegrass, and tall fescue alley treatments; however, after 32 months, the alfalfa treatment inhibited fruit tree growth and development. This was unexpected because alfalfa seemed to have a positive effect on soil fertility characteristics. Under local ecological conditions, villous wild pea had the greatest effect on apple orchard productivity and significantly increased short branching by 15.9%, fruit weight per fruit by 12.6%, yield per plant by 8.6%, and soluble sugar content by 10.5% compared with clean cultivation. The correlation analysis showed that there were significant or highly significant positive correlations between fruit tree performance and soil carbon, nitrogen, and enzyme activity levels as the soil layer depth increased. Therefore, under local ecological conditions, cover crops have a greater effect on orchard surface soil fertility than on deeper soils, and intercropping with villous wild pea potentially produces the greatest improvement in apple orchard productivity.

Exploring the impact of cover crops in integrated pest management: pest and natural enemies population dynamics in no-tillage cotton production.

Conservation agriculture plays an important role in the sustainability of production systems, notably for globally significant crops such as cotton. This study explores the integration of the no-tillage system (NTS) with integrated pest management (IPM) by incorporating cover crops. The aim is to assess the impact of these living or dead covers on the management of insect populations, the indices diversity of phytophagous insects and natural enemies, and to investigate the population fluctuation of these arthropods, considering a variety of crops in the NTS before and after cotton planting. The trial, conducted over two consecutive cropping seasons in Mato Grosso do Sul State, Brazil, employed a randomised block design with four repetitions. The treatments included cover crops with the highest potential for use in the region, such as millet (Pennisetum glaucum glaucum L.), corn (Zea mays L.), brachiaria (Urochloa ruziziensis), black velvet bean (Stizolobium aterrimum), forage sorghum (Sorghum bicolor L.), and white oats (Avena sativa L.) and a mix of white oats with brachiaria. The results indicated that the black velvet bean stands out as the most effective cover crop, providing the best performance in terms of non-preference to the attack of the evaluated pest insects. Conversely, brachiaria proves to be more susceptible to infestations of Dalbulus maidis (DeLong and Wolcott) (Hemiptera: Cicadellidae), and Diabrotica speciosa (Germar, 1824) (Coleoptera: Chrysomelidae). The study underscores the relevance of the judicious choice of cover crops in IPM and in promoting agricultural biodiversity, creating a strategic tool to enhance the sustainability and efficiency of the cotton production system in the context of the NTS.

PENGARUH REVEGETASI TERHADAP SIFAT-SIFAT TANAH PADA LAHAN BEKAS TAMBANG TEMBAGA DI NUSA TENGGARA BARAT

Copper mining activities mainly using open-pit techniques, lead to environmental issues such as overburden waste in waste dump areas that have potential to generate acid mine drainage (AMD), which can decrease soil pH and increase heavy metal toxicity. Reclamation efforts, including revegetation using pioneer plants and cover crops are necessary to restore degraded land in waste dump areas. The aim of this research is to analyze soil physical and chemical properties improvement after revegetation on copper post-mining land as an evaluation and to provide recommendations for future reclamation. The research was carried out by analyzing and interpreting laboratory data from soil observations in revegetation areas for the 2016, 2018, 2019 and 2020 planting years, as well as natural forests belonging to PT. Amman Mineral Nusa Tenggara. Revegetation of copper post-mining land does not show a significant improvement in soil physical properties because improving physical properties takes quite a long time, especially in post-mining areas with heavy structural damage. Soil chemical properties analysis shows that revegetation can increase base saturation (BS), cation exchange capacity (CEC), exch-Ca, exch-Mg, and reduce soil Al saturation. In contrast, soil pH, organic-C, total-N, and soil available-P in the revegetation area did not increase as the revegetation age increased. The effect of revegetation appears to be more significant at the age of 2 to 3 years. However, based on the Tukey test, the age of revegetation mostly does not have a significant effect on enhancing soil chemical properties.

The LTAR Cropland Common Experiment at Eastern Corn Belt.

The Eastern Corn Belt (ECB) Long-Term Agroecosystem Research (LTAR) network site is one of the most agriculturally productive areas in the United States; however, nutrient and sediment losses from this region directly contribute to water quality impairment in both the Gulf of Mexico and Lake Erie. One of the largest challenges facing agricultural production in the ECB is water management, especially under a changing climate. Shifting precipitation patterns in combination with evolving infrastructure (i.e., tile drainage, irrigation) and management (i.e., crops planted; 4R nutrient management: source, timing, rate, and placement) in response to changing climate are likely to alter water quantity and quality and agricultural productivity. Through plot- and field-scale research, the ECB Common Experiment (CE) is focused on crop, soil, and water management to support sustainable agricultural intensification, with the goal of maximizing profitability, minimizing agriculture's environmental footprint, and enhancing ecosystem services. At both spatial scales, the CE aims to examine differences in water quantity and quality between the primary prevailing crop production system in the ECB (i.e., corn [Zea mays L.]-soybean [Glycine max L.] rotation, tillage prior to corn planting, free drainage, and fertility management consistent with tri-state recommendations) and an alternative system (e.g., adding small grains into the crop rotation, cover crops, limited phosphorus fertilizer, and drainage water management). Aligning producer and stakeholders needs with research objectives and long-term data collection, the ECB CE will tackle both ongoing and newly emerging research priorities and explore the effectiveness of conservation strategies to decrease nutrient and sediment losses from agricultural land.

Winter cover crops grown in low altitude condition

The purpose of the study was to evaluate dry matter phytomass production, percentage of soil cover, and dry matter phytomass decomposition curve of cover crops in single and mix cultivation, in a low-altitude subtropical environment. The study was conducted in Santa Maria - RS, in agricultural years 2019/2020 and 2021/2022. The experimental design used was randomized blocks, with ten treatments and four replications. The experiments were conducted with four winter cover crops: White oat (WO), black oat (BO), forage turnip (FT), and common vetch (CV), in single cultivation and as a mix of cover plants. For the total production of dry matter phytomass, the FT and BO+CV+FT treatments stand out which present the highest averages between the experimental years, with values ​​4365.32 and 4109.87 kg ha-1. FT in single cultivation has a high potential for soil coverage in periods of 45 DAS, and the common vetch crop showed greater soil coverage in the late period, with 84% coverage at 90 days after sowing. The BO and WO treatments showed greater maintenance of dry phytomass in soil cover at the end of the 150-day period, presenting values greater than 40% of the initial volume of dry phytomass present in the production system. Recommending the exclusive cultivation of the species that meets the rural producer's objective.

Effect of cutting age and auxin concentration on growth of pinto peanut (Arachis pintoi)

Pinto peanuts are known as versatile cover crops for soil conservation, biomulch, and ornamental plants. These plants rarely produce seeds, so they are commonly propagated vegetatively, resulting in low efficiency of seedling production and availability of cuttings. The aim of this study was to determine the effect of cutting age and auxin application on the growth of pinto peanut. This experiment used a complete randomized block factorial design. The first factor was the age of the cuttings (stolons) with three levels (young, intermediate, old). Each cutting had three nodes, with young cuttings measured from the tip, intermediate cuttings measured from the fourth node, and old cuttings measured from the seventh node. The second factor was the concentration of the commercial auxin product ROOTONE F (0 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm). The results showed that the difference in cutting age significantly affected the number of leaves (at 10 and 50 days after planting), plant length (at 10 to 50 days after planting), number of branches (at 30 to 50 days after planting), and canopy area. Differences in auxin concentration only significantly affected plant length from 10 to 30 days after planting. The interaction between cutting age and auxin concentration was significant only for the number of leaves at 10 to 20 days after planting and plant length at 50 days after planting. The highest values for the observed parameters were consistently obtained by intermediate cuttings, which are therefore recommended as planting material for ornamental peanut cuttings.

Effects of several long-term soil health treatments on populations of Pratylenchus penetrans and the soil microbial community

Soil suppressiveness can reduce the damage by plant parasitic nematodes (PPN) in agricultural soils and is conveyed by the activity of soil microorganisms. While natural suppressiveness has been reported, it is still poorly understood if soil suppressiveness can be elicited by manipulating the soil microbial community. In the present study we assessed the number of the Pratylenchus penetrans (Pp) and the bacterial and fungal community composition over 7 years in a long-term soil health experiment. The field experiment consisted of an organic and conventional agricultural land management system and three soil health treatments (SHT): an untreated control (CT), anaerobic disinfestation (AD) and a combination of marigold cover cropping, compost and chitin amendment (CB). The land management systems were kept continuously, while the soil health treatments were applied only twice in seven years. The microbial community significantly differed between the organic and conventional system, but there was no significant difference in Pp numbers between the two systems. However, both the CB treatment and to a lesser extent the AD treatment reduced Pp numbers and increased yield with the effect being the strongest in the years immediately after the treatment. Accordingly, both the bacterial and fungal community differed significantly between the treatments, the differences being largest in the years after the treatments. Notably, the CB treatment elicited both long-term changes in the microbial community and a reduction of Pp numbers lasting for at least three years. These results indicated that a combination of treatments can lead to an altered soil microbial community in combination with persisting suppressiveness of Pp.

Quantitative inversion of soil trace elements from spectroscopic effects across multiple crop growth periods

Human health is directly impacted by trace components found in soil, for which hyperspectral remote sensing technology offers a novel way to rapidly assess dynamic soil environmental quality. In most studies, the premise of quantitative inversion on soil elements is that the known target elements will cause growth stress. However, such stress is unusual in non-polluted areas. Consequently, broad-area soil trace element monitoring in non-contaminated areas remains challenging. Spectral inversion of plant material has a longer time window and is more sensitive to elemental changes than soil spectral inversion (bare soil period). In this work, we conducted a wheat pot experiment with concentration gradients of four trace elements (Fe, B, Mo, and Zn), analyzed leaf (jointing stage) and spike (maturity period) samples using spectral measurements and chemical tests, and filtered the characteristic positions and inverse modeling using the spectra of the element-accumulating preference organs in plant canopies. The canopy aggregation sites differed for each element, and both simple linear regression (SLR) and multiple linear regression (MLR) models based on the spectra of canopy aggregation sites achieved high accuracy. The results of this study enable the construction of an inverse model of plant spectra-plant element content-elements in soil, which can serve as a reference for soil monitoring and assessment in typical crop cover areas.

Soil chemical responses to fertilization, with or without a cover crop, in an olive orchard in southwestern Buenos Aires (Argentina)

Our objective was to study the effect of fertilization on soil chemical traits on an olive orchard (artificially irrigated), considering areas with or without a cover crop, in southwestern Buenos Aires, Argentina, during the period 2020/2021. Fertilization treatments were (1) organic manure applied to the soil near the tree trunk; inorganic fertilization applied to the (2) soil or (3) to the leaves of Olea europaea L. trees; and (4) unfertilized control. Seeding of Vicia benghalensis L. and Avena sativa L. around subplots (one per each of the four studied treatments) constituted the areas with a cover crop. Subplots which were not seeded corresponded to the control areas. Soil pH was lower (p<0.05) under organic and inorganic soil fertilization. In areas without a cover crop in April 2021, soil nitrate concentrations were greater (p<0.05) under organic soil fertilization than in the control. At 0-20 cm soil depth, P concentrations were greater (p<0.05) under organic and inorganic soil fertilizations than in the other treatments. The greatest (p<0.05) K concentrations were found in the organic fertilization treatment. Organic soil fertilization on areas without a cover crop showed greater values for the soil chemical studied traits.

Monitoring the Spatial Distribution of Cover Crops and Tillage Practices Using Machine Learning and Environmental Drivers across Eastern South Dakota

The adoption of conservation agriculture methods, such as conservation tillage and cover cropping, is a viable alternative to conventional farming practices for improving soil health and reducing soil carbon losses. Despite their significance in mitigating climate change, there are very few studies that have assessed the overall spatial distribution of cover crops and tillage practices based on the farm’s pedoclimatic and topographic characteristics. Hence, the primary objective of this study was to use multiple satellite-derived indices and environmental drivers to infer the level of tillage intensity and identify the presence of cover crops in eastern South Dakota (SD). We used a machine learning classifier trained with in situ field samples and environmental drivers acquired from different remote sensing datasets for 2022 and 2023 to map the conservation agriculture practices. Our classification accuracies (>80%) indicate that the employed satellite spectral indices and environmental variables could successfully detect the presence of cover crops and the tillage intensity in the study region. Our analysis revealed that 4% of the corn (Zea mays) and soybean (Glycine max) fields in eastern SD had a cover crop during either the fall of 2022 or the spring of 2023. We also found that environmental factors, specifically seasonal precipitation, growing degree days, and surface texture, significantly impacted the use of conservation practices. The methods developed through this research may provide a viable means for tracking and documenting farmers’ agricultural management techniques. Our study contributes to developing a measurement, reporting, and verification (MRV) solution that could help used to monitor various climate-smart agricultural practices.

Nitrous oxide fluxes during a winter cover crop season in a Mississippi corn cropping system

Agroecosystems are the largest source of anthropogenic N2O fluxes. While cover crops (CC) offer benefits for soil health, their impacts on greenhouse gas fluxes are inconsistent. In the southeastern US, where intensive agriculture and low CC adoption are prevalent, few studies have investigated CC impact on soil N2O fluxes. Our study explored the effects of CC species and management practices on soil N2O fluxes during the winter CC growing season in Mississippi, which was conducted in a non-tilled corn cropping system with seven CC treatments. We measured in situ soil N2O fluxes, along with soil moisture and temperature, throughout the CC growing season from 2022 to 2023. Surface soil samples were also collected to analyze soil mineral nitrogen (N) content and enzyme activity. Over the study period (a total of 188 days), cumulative N2O fluxes were 0.50–1.03 ​kg N2O–N ha−1, with the lowest values from the annually-rotated Elbon rye treatment and the highest from the annually-rotated Austrian winter pea. Our results show that both CC treatments and sampling time significantly affected soil N2O fluxes. There was a strong positive correlation (r ​= ​0.34, p ​< ​0.05) between N2O fluxes and NO3–N content, which was lowest under continuous rye and rotated-rye treatments (0.31 and 0.34 ​mg ​kg−1 ). The results suggest that Elbon rye effectively reduced soil N2O fluxes during this period by lowering the soil NO3–N content, the primary substrate for denitrification. This study is one of the few studies to examine the impacts of cover crops on soil N2O fluxes in cropping systems in the southeastern US, offering insights into the cover crop effects on soil N2O fluxes during their growing season.

How a Long-Term Cover Crop Cultivation Impacts Soil Phosphorus Availability in a No-Tillage System?

The growth of cover crops can contribute to the increase in phosphorus content at depth by root decomposition. The aim of this work was to verify the effect of cover crops on soil phosphorus availability and use by successive plants, and the accumulation of soil P in a no-tillage system conducted for 14 years. This research was carried out during the 2016/2017 and 2017/2018 crop seasons, whose treatments have been installed and maintained since 2003. The experimental design was a randomized block design, and the plots consisted of spring crops: pearl millet, forage sorghum, sunn hemp, and additionally, a fallow/chiseling area. The evaluation of available P was determined by P fractionation. In general, in the two years of evaluation, the accumulation of P in the shoot dry matter was higher in sunn hemp growth, on average 25% higher than pearl millet in 2016 and 40% higher than sorghum in 2017. The highest contents of labile inorganic P were in the sorghum-soybean and fallow/chiseling-soybean successions, with values higher than 50 mg kg-1 of P in the 0-0.1 m soil layer. However, in the other layers analyzed, the cover crops obtained higher availability of labile inorganic P. The systems using cover crops recovered 100% of the P fertilized in soybean.

Fungal necromass contribution to carbon sequestration in global croplands: A meta-analysis of driving factors and conservation practices

Fungal necromass carbon (FNC) contributes significantly to the build-up of soil organic carbon (SOC) by supplying abundant recalcitrant polymeric melanin present in the fungal cell wall. However, the influence of a wide range of conservation practices and associated factors on FNC accumulation and contribution to SOC in global croplands remains unexplored. Here, a meta-analysis was performed using 873 observations across three continents, together with structural equation modeling, to evaluate conservation practices and factors responsible for the enhancement of FNC and SOC. FNC content (8.39 g kg−1) of North American soils was highest compared to FNC content of Asian and European soils. The structural equation models showed a significant (p < 0.05) positive influence of microbial biomass carbon (MBC), soil pH, and clay contents on the accumulation of FNC. Soil C/N ratio and climate factors, however, had only minor influences on FNC accumulation. Notably, the main driver of FNC was MBC, which is mainly influenced by the soil total N and geographic factors in the study areas. Typical 5 cropland practices had significant effect size (p < 0.05) on FNC, leading to an increase of 12 % to 26 %, and the FNC content was greatest under straw amendment (26 %). Fungal necromass accumulation efficiency ranged from 23 % to 45 % depending on cropland practices: non- and reduced tillage was the most efficient (45 %), followed by crop coverage (32 %), straw amendment (30 %), and manure application (27 %), while N fertilization had the lowest efficiency (23 %). We conclude that FNC contributes to over a quarter of SOC, highlighting its major role in enhancing C sequestration worldwide. Conservation practices, particularly non-tillage or reduced tillage, are important to enhance C sequestration from FNC in croplands.

Cover crop and wheel‐track effects on soil properties under cotton production in eastern Arkansas

AbstractRepetitive use of heavy farm machinery in cultivated agriculture may cause soil compaction that can adversely affect soil‐health‐related properties. Cover crops (CC) are well‐documented to alleviate problems associated with compaction and improve overall soil health in time. The objective of this field study was to evaluate the cumulative effects of CC treatment (i.e., with ≥ 6 years cereal rye [Secale cereale L.] CC and ≥ 4 years with no cover crop [NCC]) and sample/measurement placement (i.e., in the bed [B] and in the wheel‐track [WT] and no‐wheel‐track [NWT] furrow) on near‐surface soil physical‐, chemical‐, and infiltration‐related properties in an alluvial soil under cotton (Gossypium hirsutum L.) production in the Lower Mississippi River Valley. Samples were collected and in‐situ measurements were conducted in late May 2019 within a single field in eastern Arkansas. Overall‐infiltration rate was two times greater (p ≤ 0.01) in B compared to WT and NWT placement, which did not differ. Soil bulk density in WT was 1.1 times greater than the other two placements, while soil organic matter was greater in CC‐WT (30.7 Mg ha−1) than in all other treatment‐placement combinations, except for CC‐NWT, which did not differ. Similarly, water‐stable‐aggregate concentration was 2.3 and 1.6 times greater in the CC‐NWT and CC‐WT combinations, respectively, which did not differ, compared to under NCC. Results demonstrated that CC benefits extended beyond the bed to positively affect soil properties in adjacent WT and NWT furrows. Continued small‐scale, long‐term management studies using CC will extend insight into site‐specific, soil‐health improvements.

Phacelia and Buckwheat Cover Crops’ Effects on Soil Quality in Organic Vegetable Production in a High Tunnel System

Cover crops (CCs) are regarded as beneficial to agricultural practice as an option for soil quality improvement in field production systems. The main goal of this study was to assess the impact of spring phacelia (Phacelia tanacetifolia Benth.) and buckwheat (Fagopyrum Mill.) in a crop rotation (CC–leek–parsley, 2020–2021) on the physicochemical and biological properties of the soil in an organic high tunnel system. Soil analyses involved measurements of bulk density, water capacity, soil aggregation, soil organic carbon (SOC), available soil nutrients, as well as microbial abundance and diversity. Phacelia generated more aboveground biomass (58.2 t fresh matter ha−1) than buckwheat (33.0 t ha−1), and their biomass contained 161 kg N ha−1 and 67 kg N ha−1, respectively. A large quantity of elements, such as N, Ca, P, S, B, and Cu, were found in phacelia biomass. More Mg and Na were found in buckwheat plants. The results showed that CC biomass significantly improved some of the soil physical and chemical properties, such as soil organic carbon stock and wet aggregate stability, and decreased soil bulk density. Cover crop treatments changed the dynamics of soil bacterial and fungus populations in a high tunnel system. Phacelia increased the quantity of ammonifiers and nitrifiers in the soil substantially. Further research with a long-term focus is needed to assess the impact of cover crops on soil properties, soil quality, and subsequent crop yields in high tunnel crop rotation and management systems.