Cover Crops Research Articles

Long‐term crop yield benefits of subsurface drainage on poorly drained soils

AbstractSubsurface drainage is an important agricultural practice that has been widely utilized in the US Midwest to improve the productivity of poorly drained soils. Although widely adopted, long‐term yield benefits of drainage, particularly with varying spacings, in an ever‐changing climate are largely unknown. The goals of this study were to assess how various drainage spacings (5, 10, and 20 m) impacted crop yields compared to the undrained control in a long‐term trial (started in 1984) in southeastern Indiana and how these effects were influenced by the amount of rainfall of specific periods of the growing season. Drainage treatments led to an increase in corn (Zea mays) yields (by 12%–17%) but did not significantly affect soybean (Glycine max) yields compared to the control. In the initial 10 years of the experiment, drainage benefits were subtle and corn yields did not vary significantly across spacing treatments, whereas in the most recent 10 corn years, the drainage treatment effects became more pronounced, likely due to the combined effects of long‐term drainage system and conservation practices of no‐till and cover crops. Over 37 years, corn yields remained stagnant in the undrained plots but progressively increased in the drained treatments. Both corn and soybean yields showed a negative correlation with rainfall 14 days post‐planting, while drainage spacing treatments partially mitigated this negative effect. Our findings underscore the importance of effective drainage as a necessary prerequisite for realizing the potential benefits of conservation practices and improved crop genetics for increased crop productivity.

Spaceborne imaging spectroscopy enables carbon trait estimation in cover crop and cash crop residues

PurposeCover crops and reduced tillage are two key climate smart agricultural practices that can provide agroecosystem services including improved soil health, increased soil carbon sequestration, and reduced fertilizer needs. Crop residue carbon traits (i.e., lignin, holocellulose, non-structural carbohydrates) and nitrogen concentrations largely mediate decomposition rates and amount of plant-available nitrogen accessible to cash crops and determine soil carbon residence time. Non-destructive approaches to quantify these important traits are possible using spectroscopy.MethodsThe objective of this study was to evaluate the efficacy of spectroscopy instruments to quantify crop residue biochemical traits in cover crop agriculture systems using partial least squares regression models and a combination of (1) the band equivalent reflectance (BER) of the PRecursore IperSpettrale della Missione Applicativa (PRISMA) imaging spectroscopy sensor derived from laboratory collected Analytical Spectral Devices (ASD) spectra (n = 296) of 11 cover crop species and three cash crop species, and (2) spaceborne PRISMA imagery that coincided with destructive crop residue collections in the spring of 2022 (n = 65). Spectral range was constrained to 1200 to 2400 nm to reduce the likelihood of confounding relationships in wavelengths sensitive to plant pigments or those related to canopy structure for both analytical approaches.ResultsModels using laboratory BER of PRISMA all demonstrated high accuracies and low errors for estimation of nitrogen and carbon traits (adj. R2 = 0.86 − 0.98; RMSE = 0.24 − 4.25%) and results indicate that a single model may be used for a given trait across all species. Models using spaceborne imaging spectroscopy demonstrated that crop residue carbon traits can be successfully estimated using PRISMA imagery (adj. R2 = 0.65 − 0.75; RMSE = 2.71 − 4.16%). We found moderate relationships between nitrogen concentration and PRISMA imagery (adj. R2 = 0.52; RMSE = 0.25%), which is partly related to the range of nitrogen in these senesced crop residues (0.38–1.85%). PRISMA imagery models were also influenced by atmospheric absorption, variability in surface moisture content, and some presence of green vegetation.ConclusionAs spaceborne imaging spectroscopy data become more widely available from upcoming missions, crop residue trait estimates could be regularly generated and integrated into decision support tools to calculate decomposition rates and associated nitrogen credits to inform precision field management, as well as to enable measurement, monitoring, reporting, and verification of net carbon benefits from climate smart agricultural practice adoption in an emerging carbon marketplace.

Winter cover crop suppression methods influence on sunflower growth and rhizosphere communities.

Sunflower (Helianthus annuus L.), a vital crop for global vegetable oil production, encounters sustainability challenges in its cultivation. This study assesses the effects of incorporating a winter cover crop (CC), Avena sativa (L.), on the subsequent growth of sunflower crops and the vitality of their rhizosphere microbial communities over a two-year period. It examines the impact of two methods for suppressing winter CC-chemical suppression using glyphosate and mechanical suppression via rolling-both with and without the addition of phosphorus (P) starter fertilizer. These approaches are evaluated in comparison to the regional best management practices for sunflower cultivation, which involve a preparatory chemical fallow period and the subsequent application of starter P fertilizer. The methodology utilized Illumina sequencing for the analysis of rhizosphere bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) amplicons. Findings indicate a significant improvement (9-37%) in sunflower growth parameters (plant height, stem diameter, head diameter, and head dry weight) when cultivated after glyphosate-suppressed winter CC compared to the chemical fallows. Conversely, rolling of winter CC generally negatively affected sunflower growth. Rhizosphere bacterial communities following chemical suppression of winter CC showed greater Pielou's evenness, indicating a uniform distribution of species. In general, this treatment had more detrimental effects on beneficial sunflower rhizosphere bacteria such as Hymenobacter and Pseudarthrobacter than rolling of the winter CC, suggesting that the overall effect on sunflower growth may be mitigated by the redundancy within the bacterial community. As for fungal diversity, measured by the Chao-1 index, it increased in sunflowers planted after winter CC and receiving P fertilization, underscoring nutrient management's role in microbial community structure. Significant positive correlations between fungal diversity and sunflower growth parameters at the reproductive stage were observed (r = 0.41-0.72; p < 0.05), highlighting the role of fungal communities in plant fitness. The study underscores the positive effects of winter CC inclusion and management for enhancing sunflower cultivation while promoting beneficial microbes in the crop's rhizosphere. We advocate for strategic winter CC species selection, optimization of mechanical suppression techniques, and tailored phosphorus fertilization of sunflower to foster sustainable agriculture.

Impact of agroecological practices on Phytoseiidae communities in a vineyard of South of France: effect of covercrops and agroforestry.

Viticulture is characterized by substantial pesticide applications, impacting natural enemies. New pest control strategies and management of plant diversity into agrosystems acting as reservoirs of natural enemies are assumed to limit pesticide use. Various studies support this hypothesis but gaps exist on the effect of diversification on Phytoseiidae mites, generalist predators reported as prevalent and efficient natural enemies in vineyards. This study focuses on the effect of cover crop management (no cover crop, spontaneous cover crops with or without agroforestry) and grape variety (resistant cv. Artaban and cv. Syrah) on predatory mites and prey communities, in a newly planted experimental vineyard in South-East France. Samplings were carried out three times a year on vine, cover crops, and co-planted trees. Phytoseiidae, Tydeiidae, Eriophyidae mites and thrips were characterized. Nine Phytoseiidae species were identified on vine, the main ones being Kampimodromus aberrans, Typhlodromus exhilaratus, Phytoseius finitimus and Euseius gallicus. Kampimodromus aberrans was prevalent on the cv. Syrah, highlighting a strong effect of variety. The low unexpected effect of system management observed outcome could be due to several factors, such as the experimental plot size or the influence of vine stress on Phytoseiidae communities in vines with cover crops. All phytoseiid species present on vine were identifed at least once on cover crops and co-planted trees, suggesting their potential role as reservoirs. Further studies should be performed investigating the evolution of communities in this newly-planted experimental system, as well as potential differences in trophic network interactions.

Influence of cover crops on soil aggregate stability, size distribution and related factors in a no-till field

Soil aggregation plays an essential role in maintaining soil structure. A three-year field experiment was undertaken to explore the effects of cover crops on soil aggregate stability indices (mean weight diameter, water-stable aggregates greater than 0.25 mm, and soil erodibility factor), size distribution and their correlations with nine soil physical and chemical properties (soil bulk density, pH, organic carbon, total nitrogen, C/N, calcium, phosphorus, potassium, and cation exchange capacity) at 0–5 and 5–10 cm depths in a Marietta silt loam soil in a no-till field, Northeastern Mississippi. The cover crop treatments included elbon rye (Secale cereale L.), daikon radish (Raphanus sativus ssp. acanthiformis), Austrian winter field peas (Lathyrus hirsutus), and their mixture. The samples were wet-sieved to five size classes of aggregates (> 2, 2–1, 1–0.5, 0.5–0.25, and < 0.25 mm). Results showed that the < 0.25 mm aggregates dominated (50.95–78.02 %) soil aggregate size distribution at 0–5 and 5–10 cm depths. The rye plot soil displayed the greatest values for mean weight diameter (0.58 mm) in the two soil depths. Soil water-stable aggregates greater than 0.25 mm value under peas was significantly higher by 68.61 % compared to the no cover crop treatment at 0–5 cm depth, while soil erodibility factor did not change significantly. Mean weight diameter, water-stable aggregates greater than 0.25 mm, soil erodibility factor, 1–0.5 mm aggregates, and < 0.25 mm aggregates were significantly correlated with soil organic carbon, pH, bulk density, phosphorus, and potassium. The dominant factors driving changes in three aggregate stability indices and size fractions (excluding 2–1 mm aggregates) were bulk density and pH. Furthermore, high pH restricted soil aggregate stability and size distribution. This study demonstrated the positive impact of cover crops, specifically peas and rye, on soil aggregate stability and size distribution. This study will provide valuable information for future research on soil stabilization in crop production management systems.

Determination of C-factor for conventional cultivation and soil conservation technique used in hop gardens

Abstract The research presented in the article was focused on determining the C-factor for hops for conventional cultivation (CT) and soil conservation technique, which is based on the presence of cover crops (CC) in the inter-rows. The values of the soil loss ratio, which are the basis for the calculation of the C-factor, are also presented. The research activities were carried out between 2016 and 2023 and a field rainfall simulator was used for the measurements. Rainfall simulations were conducted at three developmental stages of CC. The results show a high C-factor value for CT (0.73), which indicates insufficient erosion control efficiency. In contrast, a C-factor of 0.16 was determined for the cover crop technique. This means that cover crops in the inter-rows of hop gardens can effectively reduce the risk of water erosion. The values reported in the article can be used as input parameters in various erosion models and equations to refine the subsequent calculation.

Determinants of climate change adaptation strategies and intensity of use; micro level evidence from crop farmers in Kenya

Climate change and its negative impacts pose a threat to crop production in Kenya. However, climate change adaptation strategies have the potential to address the challenges faced by crop farmers. Despite this, there is limited literature to inform policy on the best interventions to help farmers deal with climate issues. This study assessed the determinants of climate change adaptation strategies and the intensity of their use among 723 crop farmers in Busia County, Kenya, selected through a multistage sampling technique. Data were collected using a structured questionnaire and analyzed using principal component analysis (PCA), multinomial logit regression, and the ordered probit model. The climate change adaptation strategies were categorized into crop diversity, cover crops, use of drought-resistant crops, and irrigation. According to the results, the factors contributing to the uptake of the different adaptation strategies were age, household size, access to credit, training access, off-farm income, group membership, frequency of receiving climate change information, and extension services. The major factors influencing the uptake of multiple climate change adaptation strategies were access to credit and off-farm income. The study shows that certain adaptation strategies, such as using cover crops, do not require credit and offer an important option in an environment with limited resources. On the other hand, adaptation measures such as irrigation demand financial resources for farmers to implement them, highlighting the importance of information and awareness in adopting adaptation strategies and the supportive role of financial resources, particularly for adopting multiple strategies. Therefore, this study suggests implementing policies and interventions that encompass knowledge-based strategies such as extension services, training, climate change education, group participation, and financial mechanisms like income generation activities and access to credit. These integrated strategies will enable farmers to adopt various climate change adaptation methods for sustainable crop production.

Enhancing Soil Health and Fertility Management for Sustainable Agriculture: A Review

In modern agriculture, ensuring soil health and effective fertility management are paramount for sustainable crop production and environmental stewardship. This review article comprehensively explores a spectrum of strategies aimed at enhancing soil health and fertility management within the context of sustainable agriculture. Beginning with an overview of the pivotal role soil health plays in agricultural systems, the review meticulously examines the significance of adopting sound soil fertility management practices to sustain soil productivity while mitigating adverse environmental impacts. Traditional and innovative approaches to soil management are thoroughly discussed, encompassing a range of practices such as organic amendments, cover cropping, crop rotation, reduced tillage, and integrated nutrient management. These practices, deeply rooted in agricultural traditions, are shown to enhance soil structure, foster nutrient cycling, and promote beneficial soil microbial communities, thereby contributing to long-term soil health and productivity. Furthermore, the review elucidates emerging technologies and methodologies that hold promise for revolutionizing soil health and fertility management in sustainable farming systems. Precision agriculture techniques leveraging GPS, remote sensing, and data analytics are highlighted for their potential to optimize resource use and improve crop management practices. Biochar application, a burgeoning area of research, is explored for its ability to enhance soil fertility, sequester carbon, and improve soil water retention. Additionally, manipulation of the soil microbiome through innovative techniques presents exciting opportunities for enhancing soil health and resilience, the review underscores the importance of continued research, education, and policy support in promoting sustainable soil management practices. Recommendations for future research directions are provided, emphasizing the need for interdisciplinary collaborations, long-term field studies, and farmer participatory research. Practical implications for farmers and policymakers are also delineated, emphasizing the imperative of adopting holistic approaches to soil management that integrate traditional wisdom with cutting-edge technologies. By embracing sustainable soil management practices, farmers and policymakers can safeguard soil health, enhance agricultural productivity, and ensure the long-term sustainability of our food systems and environment.

Evapotranspiration and crop coefficients of some vegetable crops grown under greenhouse conditions

ABSTRACT In this study, it was aimed to determine the Kc of tomato, eggplant, pepper and cucumber grown in two consecutive seasons in a year in a common type of plastic greenhouse, using the reference (grass) (ETo) and crop evapotranspiration (ETc) values measured directly in lysimeters. The study was carried out at drainage-type lysimeters placed in the greenhouse, with three replications for each crop and grass at Akdeniz University, Antalya, Turkey, from 2019 to 2020. Seasonal ETo values varied between 206.0 and 329.1 mm, while seasonal ETc values of crops varied between 243.6 and 529.3 mm for growing seasons ranging from 105 to 137 days. The crop coefficient (Kc) of the tomato, eggplant, pepper and cucumber crops under greenhouse conditions were between 0.4 and 0.6 for the initial stage (Kc ini); for maximum Kc values (mid-season stage) (Kc mid) between 1.4 and 1.8 in spring and 1.6–1.9 in fall; for the end-of-season stage (Kc end) it varied between 1.1 and 1.8 in spring and 0.7–1.4 in fall. It was concluded that the Kc values were higher due to the fact that the ground cover development and crop architecture changed significantly in the greenhouse compared to the field conditions.

Role of Nitrogen in Wheat Production System and Nitrogen for Improving Wheat Yield and Quality: A Review

Wheat is the staple food across the different parts of the world. To increase the wheat productivity by utilizing the fertilizers. Nitrogen plays a key role in increasing productivity and the quality of the crops. In this review article, we studied the relationship between nitrogen and wheat parameters, the impact of excessive nitrogen used in wheat, NUE (Nitrogen use efficiency) in wheat production, and examined various nitrogen management strategies aimed at enhancing both yield and quality. Different nitrogen application techniques, such as broadcast and side-dressing, have been evaluated, with the rate of nitrogen showing a significant influence on wheat parameters. Key components influencing NUE in wheat farming, including soil characteristics, nitrogen application timing and rate, environmental factors, and crop genetics, are discussed. Furthermore, innovative nitrogen management practices such as precision farming techniques, cover cropping, and the use of biofertilizers as effective strategies for improving NUE and promoting sustainable wheat production. The abstract underscores the importance of balancing nitrogen application to meet crop demands at different growth stages while minimizing nitrogen losses and environmental risks. By integrating advanced technologies, agronomic practices, and scientific insights, farmers can optimize nitrogen use efficiency in wheat production systems, thereby enhancing both yield and quality outcomes.

Optimal timing for fava bean planting, pod harvesting, and termination in Northern California

Fava bean has been cultivated as a grain, vegetable, and cover crop in California for more than a century. Despite a decline in popularity as a grain, many growers are taking a second look to satisfy demands for vegetable fava bean (pod) and to provide plant-derived nitrogen (N) to grow summer cash crops. This paper presents the results of a series of experiments aimed at quantifying fava bean biomass and N at planting date and termination, as well as pod production in response to the harvest scheme. Sowing before the end of October resulted in the highest biomass and N in Northern California. Termination of fava bean cover crops in early April between the flowering and first pod stage increased the forage yield of the following crop (sudangrass), compared to termination at the earlier branching stage, which is typically in late February. We found that delaying vegetable pod harvest until the end of the growing season resulted in low fresh-pod yields. The results provide a starting point for growers interested in incorporating fava bean.

Integrating Cover Crops into Soybean Systems in the Southern Great Plains: Impacts on Yield and Yield Components

The implementation of cover crops in crop rotation is a suggested soil health practice. As cover crops are not harvested and sold, they do not directly provide monetary gain to producers. Therefore, it is imperative that planting cover crops does not negatively affect the subsequent cash crop. However, there is no overall consensus in the literature regarding the effects of cover crops on cash crop yield. To better understand the effects of cover crops on soybean growth and yield in Oklahoma soybean systems, trials were conducted in Bixby, OK, in 2019 and Perkins, OK, in 2019, 2020, and 2021. The objectives of these trials were to (1) determine how different cover crop mixes affect soybean growth parameters and (2) determine if cover crops significantly influence soybean seed yield. Treatments within the trials included six cover crops and a fallow treatment. Soybeans were planted after the termination of the cover crops. Yield and growth parameter data were collected after harvest. No significant differences or consistent trends were detected in the yield among treatments. While cover crops had a significant impact on the number of three- and four-bean pods, no other differences in the growth parameters existed, and they never translated into significant yield differences. Based on our data, cover crops would not benefit the overall cash crop production in the continuous cover crop soybean system in Oklahoma. However, the fact that cover crops did not consistently or significantly reduce soybean yield allows growers to explore other benefits, such as weed management or soil health improvement.

Alternative Cover Crops and Soil Management Practices Modified the Macronutrients, Enzymes Activities, and Soil Microbial Diversity of Rainfed Olive Orchards (cv. Chetoui) under Mediterranean Conditions in Tunisia

In Tunisia, the olive is the most cultivated fruit crop in the northern region, where annual rainfall exceeds 400 mm. This olive-growing area is characterized by a wide coverage of marginal soil with a high slope gradient. Therefore, the inclusion of cover crops in olive orchards is a sustainable solution to enhance ecosystem productivity, improve soil fertility, and increase oil yields. This study aimed to investigate the short-term (two cropping seasons in 2021 and 2022) effects of different seeded cover crops and soil management practices on soil characteristics, as well as soil health by measuring soil enzyme activities and microbial diversity. Six cover crop types consisting of wheat, vetch, oat, fenugreek, a vetch–oat mixture, and spontaneous vegetation were tested in association with rainfed olive trees (cv. Chetoui) in the north of Tunisia and compared to a control (which was tilled periodically three times per year without intercropping). During the first cropping season, cover crops were cut as animal feed, and only residues were incorporated into the soil. However, during the second year, all cover crop biomass was incorporated into the soil. The results indicated that the dry biomass production and carbon uptake were significantly higher in grass species (wheat and oat). All of the cover crops, including the spontaneous vegetation, significantly increased soil organic matter (SOM) and macronutrient levels, mainly, available phosphorus. On the other hand, the highest level of soil nitrogen was found in the fenugreek cover crop. The soil enzyme activities in the cover crops of wheat, oat, and the vetch–oat mix were higher than those in the control. Together with the increase in soil organic matter (SOM), this demonstrates a significant improvement in soil health with cover crops. Furthermore, this study proves that the utilization of carbon sources was dominated by amides, amines, and amino acids in the fenugreek plot, while it was dominated by polymers and carboxylic acids in the case of the wheat and oat. Overall, this study demonstrates that seeding cover crops is a sustainable management practice not only to integrate livestock but also to improve soil health in semiarid olive orchards.

Theoretical and practical propositions for more sustainable livestock production

A brief review is made of theoretical and practical propositions for more sustainable livestock production (meat and milk). An Organic Livestock Conversion Index (OLCI) was developed to evaluate the level of approximation of Livestock Production Units (LPU) to the organic model. Organic practices such as crop rotation, use of cover crops, mechanical and manual weed control, and recycling of manure reduce soil erosion and pest problems and generally allow for avoiding the use of chemical fertilizers and pesticides, which - along with the substitution of nitrogen fertilizer with legumes and/or manure – reduces energy use in organic systems. Furthermore, practices by LPU contribute to sustainable livestock production by means of minimal use of chemical fertilizers in pastures; adding nutrients to the soil solely by cattle depositing manure during grazing, manual weed control, use of silvopastoral systems, and energy efficiency by the farmers. The approximation of the LPU to organic production, the use of organic practices, Silvopastoral Systems and more energy efficiency demonstrate the potential of organic livestock farms for contributing to more sustainable production as compared to conventional livestock production.

A regional examination of the footprint of agriculture and urban cover on stream water quality

Freshwater systems in cold regions, including the Laurentian Great Lakes, are threatened by both eutrophication and salinization, due to excess nitrogen (N), phosphorus (P) and chloride (Cl−) delivered in agricultural and urban runoff. However, identifying the relative contribution of urban vs. agricultural development to water quality impairment is challenging in watersheds with mixed land cover, which typify most developed regions. In this study, a self-organizing map (SOM) analysis was used to evaluate the contributions of various forms of land cover to water quality impairment in southern Ontario, a population-dense, yet highly agricultural region in the Laurentian Great Lakes basin where urban expansion and agricultural intensification have been associated with continued water quality impairment. Watersheds were classified into eight spatial clusters, representing four categories of agriculture, one urban, one natural, and two mixed land use clusters. All four agricultural clusters had high nitrate-N concentrations, but levels were especially high in watersheds with extensive corn and soybean cultivation, where exceedances of the 3 mg L−1 water quality objective dramatically increased above a threshold of ‍∼30 % watershed row crop cover. Maximum P concentrations also occurred in the most heavily tile-drained cash crop watersheds, but associations between P and land use were not as clear as for N. The most urbanized watersheds had the highest Cl− concentrations and expansions in urban area were mostly at the expense of surrounding agricultural land cover, which may drive intensification of remaining agricultural lands. Expansions in tile-drained corn and soybean area, often at the expense of mixed, lower intensity agriculture are not unique to this area and suggest that river nitrate-N levels will continue to increase in the future. The SOM approach provides a powerful means of simplifying heterogeneous land cover characteristics that can be associated with water quality patterns and identify problem areas to target management.

Quantifying the carbon sequestration potential of different soil management practices aimed at increasing organic content in soil and reducing the usage of chemical inputs

&lt;p&gt;The global imperative to address climate change and promote sustainable agriculture has underscored the critical role of soil management practices in enhancing carbon sequestration and reducing greenhouse gas emissions. This research focuses on quantifying the carbon sequestration potential of diverse soil management techniques aimed at increasing organic content in soil while minimizing the use of chemical inputs. It integrates a multidisciplinary approach, conducting field experiments across diverse agroecological regions with different soil types and cropping systems. Key practices under investigation include cover cropping, crop rotations, conservation tillage, compost application, organic amendments, integrated pest management (IPM), and precision agriculture. The study assesses their impact on soil organic carbon levels, greenhouse gas emissions, soil health indicators, and crop productivity through comprehensive data collection and analysis techniques. Statistical analyses and modeling are employed to quantify carbon sequestration rates, evaluate treatment effects, and assess environmental and agronomic benefits. These practices are implemented in controlled trials to assess their impact on soil organic carbon (SOC) levels, greenhouse gas emissions (CO2, CH4, N2O), soil health indicators (microbial biomass, nutrient cycling, soil structure), and crop productivity. Data collection and analysis techniques involve comprehensive soil sampling, greenhouse gas flux measurements, soil health assessments, and crop yield monitoring over multiple growing seasons. Statistical analyses and modeling approaches are employed to quantify the carbon sequestration rates, assess treatment effects on soil health and greenhouse gas emissions, and evaluate the overall environmental and agronomic benefits of the soil management practices. The study aims to contribute valuable insights into evidence-based strategies for promoting sustainable soil management practices that enhance carbon sequestration while maintaining or improving agricultural productivity. The findings will have implications for informing agricultural policies, guiding farm management decisions, and advancing research on climate-smart agriculture. By quantifying the carbon sequestration potential of different soil management practices, this research contributes to the broader goal of achieving climate resilience, environmental sustainability, and food security in agricultural systems.&lt;/p&gt;

Soil respiration response to reductions in maize plant density and increased row spacing (Southeast pampas, Argentina)

Previous studies have recognized the influence of crop cover and agricultural management on variables (soil temperature, soil moisture, and root biomass) that influence soil respiration. However, despite the influence of plant density and row spacing on these variables in the maize crop (Zea mays L.), their impact on soil respiration has received little attention. Thus, the aims of this study were (i) to investigate whether reducing plant density and row spacing influences soil respiration, and (ii) to identify the controlling variables (soil temperature and soil moisture) underlying this response. We conducted field experiments in Balcarce, Argentina, over two seasons. Treatments included (i) maize crops at high plant density (≈8 plants m−2) and narrow rows (0.52 cm, HDN), and (ii) maize crops at low plant density (≈6.5 plants m−2) and wide row spacing (0.70 cm; LDW). Leaf area index (LAI), soil CO2 fluxes, soil superficial temperature, and moisture (characterized by the water-filled pore space, WFPS) were assessed throughout the growing season. Grain yield and cumulative soil CO2 emissions were determined at the final harvest. Major findings relevant to understanding the influence of reducing plant density and wider row spacing on instant CO2 fluxes include: (i) LAI reductions were related to higher superficial soil moisture, which was consistent at LAI ≥ 3; suggesting higher decreases in water uptake than increases in soil evaporation, and in turn (ii) increments in soil moisture were associated with higher CO2 fluxes. While lower plant density and wider row spacing had notable short-term effects on WFPS and soil respiration fluxes, they did not significantly affect cumulative soil respiration throughout the growing season. However, the combination of this practice with low-yield potential genotypes that exhibit low stability to changes in resource availability can increase CO2 emissions per unit of grain yield. These findings contribute to a better understanding of the impacts of management practices on soil respiration and, consequently, on carbon cycling within agricultural ecosystems.

Effects of cover crops and nitrogen fertilizer on greenhouse gas emissions and net global warming potential in a potato cropping system

The study was conducted to investigate the effects of cover crops and different nitrogen levels on greenhouse gas emissions and net global warming potential in a potato production system during the 2018–2019 and 2019–2020 growing seasons at the Agricultural Research Farm of Razi University, Kermanshah, Iran. The experiment was arranged as a split plot based on a randomized complete block design with three replications. The main factor was cover crop including hairy vetch, rye, mixed (rye + hairy vetch), and control (no cover crop), and the sub factor was nitrogen fertilizer (as urea) at four levels consisted of 0 (control), 33, 66 and 100 % of the recommended nitrogen fertilizer based on the soil test. Results showed that the use of cover crops as green manures increased net ecosystem carbon balance (NECB) and the highest NECB was observed in the mixed treatment (rye + hairy vetch) along with the 66 % of nitrogen fertilizer. The mixed cover crops (hairy vetch + rye) along with the 100 % of nitrogen fertilizer showed higher CO2 emission and, while hairy vetch along with the 100 % of nitrogen fertilizer had higher emissions of N2O and CH4 during the potato growing season. It can be concluded that the use of cover crops as green manures before the planting of potato can notably increase greenhouse gas emissions and the net global warming.

Assessment of Soil and Water Salinity Status of Bitata Small Scale Irrigation Scheme of Guji Zone Oromia, Ethiopia

The Soil salinity, sodicity and water logging are becoming an emerging challenge for the irrigation development. So, assessments of irrigation schemes are very important to see the problems they have. The assessment of soil and water salinity status of Bitata small scale irrigation scheme of Guji Zone, Oromia region was done to identify, analyze and map salinity level using Geographic information System, the chemical properties of the soil was done at laboratory for samples analysis. After, spatial analyst and interpolation by Inverse distance Weight and Re-class the soil analyzed. Then the area of influence of the points was determined for the selected parameters and the results of investigation shows the majority of sample results are non-saline non sodic, even if, the samples were less, the sodicity problems occur at the study area on surface soil by considering three parameters at once and non-saline and non-sodic for profile soil. And when considering individual parameters of surface soil the results shows slightly saline depends on Electrical conductivity of saturation extracts, considering the exchangeable sodium percentage slightly to extremely sodic results was observed. And the results of irrigation water quality shows Very high Saline and Low Sodicity. The finding of the study recommends intervention of sodicity for surface soil and salinity and sodicity for water source used for irrigation is very important to control the expansions of it to the whole area of the scheme and to minimize the risk of salinity and sodicity problems of the water source used for irrigation. Management techniques that improve soil fertility such as crop rotations, manuring, fallow periods, proper management of crop residues, vermicomposting and leguminous cover crops and water-saving irrigation technologies suitable to the land of the area are the best options. And similar work is necessary to get additional information of the study areas because of the results of surface and profile soil and water source used for irrigation were far apart from each other.

Soil carbon stocks as affected by land-use changes across the Pampa of southern Brazil

ABSTRACT The “campos” of the Pampa are unique Brazilian ecosystems, which provide key environmental services, including C storage. These grassy ecosystems have been rapidly converted to intensive land-uses, mainly intensive grain crops (soybeans) and Eucalyptus silviculture. These new land-uses could decrease soil C stocks, depending on soil management. This study aimed to assess soil organic carbon (SOC) changes after the conversion of native grasslands to cropland (soybeans/cover crops under no-tillage) and forestry (Eucalyptus). Eight representative sites in this biome were selected for soil sampling (Alegrete-ALE, Aceguá-ACE, Jari-JAR, Jaguarão-JAG, Pinheiro Machado-PIM, Lavras-LAV, Santo Antônio das Missões-SAM, São Gabriel-SAG). Soil sampling was conducted in dug pits (0.30 m wide × 0.30 m long × 0.40 m depth) spaced by 50 m at each site, to 0.30 m depth. Soil bulk density and SOC were obtained by samples obtained with volumetric rings. Soil organic C was analyzed by dry combustion. Soil C stocks were calculated per layer and cumulatively (0.00-0.20 and 0.00-0.30 m). Soil C content was higher under grasslands in soils from sites with finer, clayey texture (ACE, JAG), and lower in soils at sites with sandier topsoil. Land-use conversion to silviculture and cropland minimally affected SOC stocks. The same pattern was observed with soil N, because of the tight connection between C and N cycles. Soil bulk density was similar across sites and layers, but higher values were measured in sites with coarser texture. Mean SOC stock of the grassland sites was 62 ± 24.6 Mg ha -1 , similar to 66 Mg ha -1 reported for grasslands soils of Rio Grande do Sul State, and higher than that reported by IPCC for this region (55 ± 4.4 Mg ha -1 ). Adopting these default values would lead to underestimation of baseline SOC stocks in the region. Land-use conversion to cropland did not affect SOC stocks significantly, probably because of the adoption of no-tillage system with winter cover crops. Soil C stocks were lower in Eucalyptus stands in the 0.00-0.30 m soil layer, which could be attributed to intensive soil management at planting and lower soil fertility in some sites. This lack of effect of conversion on soil C was attributed to the short time since conversion and adoption of soil conservation practices (no-tillage) in cropland. The study contributed to reduce existing soil data gaps in the region and supports Brazilian public initiatives like the ABC Program and National Greenhouse Gas Inventories.