Agronomy

Cover cropping serves as a promising technique with great potential to enhance soil organic carbon (SOC), boost crop productivity, and improve soil quality. The implementation of cover crops as a sustainable agricultural practice has gained popularity worldwide. To further evaluate the role of cover cropping, this systematic review examines empirical evidence from 38 peer-reviewed studies published between 2015 and 2025 to assess the impact of cover cropping on these key outcomes. Studies were selected based on strict inclusion criteria requiring original field data or validated modeling results that evaluated all three outcomes, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data on cropping system, duration, type of cover crop, and outcome metrics were extracted. More than 80% of the literature reported benefits. Multi-species cover crop mixtures that were managed long-term enhanced SOC by 5–30%, with 87% and 55% of studies demonstrating enhanced soil quality and yield, respectively. However, some studies recorded yield reductions in drought-prone regions or when cover crops were terminated at inappropriate times. In some studies, improvements in microbial function and nutrient cycling were observed while several United States (U.S.) studies focused more on physical and biological indicators under dryland conditions. Although outcomes vary by context, cover crops are widely recognized as a viable strategy for climate-smart agriculture and sustainable soil management. To optimize benefits, there is a need for region-specific incentives, targeted agricultural policies, and standardized agronomic guidelines. Cover crops represent a key strategy for climate change mitigation and sustainable soil management. This review reveals that species diversity and long-term adoption are crucial for achieving reliable results. With the integrative focus of this review on the tripartite relationship between SOC, crop yield, and soil quality, as well as its comparative lens on global versus U.S. practices, it is novel because it offers crucial insights for evidence-based policy development and region-specific cover cropping strategies.

The sustainable management of dredged sediments contaminated with heavy metals represents a major environmental challenge. This study evaluated the phytoremediation potential of hemp (Cannabis sativa L.) and sorghum (Sorghum bicolor L.) cultivated in metal-enriched sediment from the Bega Canal (Cu = 204 mg kg⁻¹, Pb = 171 mg kg⁻¹, Cr = 281 mg kg⁻¹, Ni = 56 mg kg⁻¹, Cd = 6.8 mg kg⁻¹) and examined the effects of glutamic (GA) and tartaric (TA) acids (20 mmol kg⁻¹) on sediment properties and metal uptake. Pot experiments under natural conditions (n = 3, 6–8 weeks) showed that GA treatment resulted in cation exchange capacity (CEC) values ranging from 31.0 to 58.5 cmol_c kg⁻¹, which were lower than in the initial sediment (60.7 cmol_c kg⁻¹) but still higher than in the corresponding controls and TA treatments. GA also increased electrical conductivity from 435 to 1189 µS cm⁻¹, which may indicate enhanced ion mobility and be consistent with redox-related processes, whereas TA maintained near-neutral pH (8.0–8.2) and caused only minor changes in CEC and EC, preserving overall structural stability. Hemp produced up to 40% more biomass than sorghum and allocated a relatively larger share of Cu, Pb and Cd to shoots, whereas sorghum retained up to 80% of total Cr and Ni in roots. Bioaccumulation factors ranged from 4.3 for Cu in hemp (GA) to 20.8 for Cu in sorghum (GA), while translocation factors remained <1.0 in both species, indicating that root-based phytostabilization was the dominant mechanism. The results demonstrate that combining low-molecular-weight organic acids with energy crops can effectively enhance metal mobility and plant uptake, offering a viable route for sediment remediation and biomass valorization within circular economy strategies.

Research on microplastics (MPs) in agricultural soils has received increasing attention due to their potential ecological risks and adverse effects on the food chain. Recently, geostatistical approaches have been increasingly used to assess the spatial distribution of MPs in soils. Therefore, this study aims to predict the abundance of MPs in the soil of an agricultural micro-watershed using geostatistical methods and to produce a continuous map of the interpolated MPs. Soil samples were collected, and MP abundance was determined using the density separation method. Subsequently, exploratory data analysis was conducted, followed by the construction of the experimental semivariogram, theoretical variogram model fitting, ordinary kriging interpolation, cross-validation and, inverse distance weighting (IDW) interpolation. MPs were detected in all samples, with average abundances of 3826, 2553, and 3407 pieces kg⁻¹ in forest, pasture, and agricultural land use systems, respectively. The experimental semivariogram showed that the spatial distribution of MPs has a weak spatial dependence structure. The Kriging and IDW maps showed a distribution of MPs in the range of 600 to 7400 pieces kg⁻¹, with higher concentrations of MPs for forest and agricultural areas. Additionally, the map reveals a high abundance of MPs, with greater concentrations in depressions and areas near roads and urban centers, allowing for identifying critical points within the micro-watershed. This study offers important insights into the presence of MPs across various land uses, emphasizing the need for proactive measures to prevent and mitigate their accumulation in soil.