The global increases in the surface and groundwater nitrate (NO₃⁻) concentrations due to synthetic fertilizer input have emerged as major sustainability threats to terrestrial and aquatic ecosystems. Cover crops can reportedly reduce nitrate leaching from croplands. However, the underlying mechanisms and the effectiveness of cover crops in reducing nitrate leaching across species, soil types, agronomic management, and climates remain elusive. We conducted a global meta‐analysis to evaluate the effects of cover crops on nitrate leaching and water drainage. A random‐effects analysis was established to investigate seven moderating variables in 41 articles. Results showed that globally, cover crops reduced nitrate leaching by 69% compared with fallow while demonstrating no effect on water drainage. Overall, cover crops from Brassicaceae and Poaceae families showed the greatest effect with 75% and 52% reduction in nitrate leaching, respectively. Cover cropping on Ultisols, Histosols, and Inceptisols resulted in the greatest reduction in nitrate leaching (77%, 78%, and 77%, respectively). Greater efficacy of cover crops at reducing nitrate leaching was evident with increasing soil sand content. In general, cover crops appeared to perform better to reduce nitrate leaching in vegetable systems compared to field crops. Cover cropping on conventional tillage resulted in a 63% reduction in nitrate leaching compared with no‐tillage (50%) and reduced tillage (38%) systems. The impact of cover crops on water drainage was nonsignificant which implies that nitrate leaching control by cover crops is unlikely exerted through reducing water drainage. This study brings further insight into the intrinsic factors affecting cover crop efficacy and management practices that enhance cover crop potential in reducing nitrate leaching from agricultural systems.

We investigated the individual and synergistic impact of gypsum, elemental sulfur, vermicompost, biochar, and microbial inoculation on soil health improvement in degrading calcareous saline-sodic soils. We developed Linear and nonlinear soil health quantification frameworks to assess the efficacy of remedial practices. The combined inoculated chemical and organic treatments; gypsum + vermicompost and elemental sulfur + vermicompost with 134% (0.29 versus 0.68) and 116% (0.29 versus 0.62) increases in nonlinear index, significantly increased the efficacy of amendments compared with control. An increase in the overall soil health index ranged between 12 to 134%. Microbial inoculation further enhanced the impact of treatments on soil health. Soil health properties included in the indexes explained 29 to 87% of the variance in wheat growth. The findings bring insight into the cost-effective and environmentally sustainable practices to recover degraded saline-sodic soils. Furthermore, the introduced soil health indexes offer a quantitative evaluation of soil remediation strategies.

Climate extremes pose a global threat to crop security. Conservation agriculture is expected to offer substantial climate adaptation benefits. However, synergistic effects of conservation practices on yield during normal versus extreme climates and underlying regulatory mechanisms remain elusive. Here, we analyze 29-years of climate data, cotton (Gossypium hirsutum L.) yield, and soil data under 32 management practices in Tennessee, USA. We find that long-term no-tillage enhanced agroecosystem resilience and yield stability under climate extremes and maximized yield under favorable climate. We demonstrate that no-tillage benefits are tied with enhanced soil structural stability and organic carbon. No-tillage enhanced the effectiveness of legume cover crop in stabilizing cotton yield during relatively dry or wet, and dry years, while nitrogen fertilizer rate and precipitation timing, controlled yield stability in wetter years. Our findings provide evidence-based insights into how management strategies can enhance agroecosystem resilience and production stability in climate extremes.

Dwindling water resources have drawn global attention to the reuse of treated wastewater (TWW) for irrigation. However, the impact of continuous TWW applications on soil quality and the proper quantification and monitoring frameworks have not been well-understood. This study aims to provides an insight into the impact of flood irrigation of urban TWW on soil nutritional-chemical attributes and the potential application of multiple soil quality indices for a corn cropping system. To achieve that goal, we pursued the Total Data Set (TDS) and Minimum Data Set (MDS) approaches, as well as the Integrated Quality Index (IQI) and Nemoro Quality Index (NQI) models. A total of 17 soil nutritional-chemical indicators (0–50 cm depths) were determined for the soils irrigated with TWW (five sites) and well water (one site as control) in West Azerbaijan province in northwestern Iran. Results revealed a significant difference in the majority of soil nutritional-chemical attributes, IQI-TDS, NQI-TDS, IQI-MDS, NQI-MDS, and corn yield between the TWW-irrigated and well-irrigated soils. Irrigation with TWW resulted in a significant increase in the amount of organic matter and cation exchange capacity by 9–17% and 17–26%, respectively, macronutrients (N, P, K, Ca, and Mg) by 22–164%, and the majority of trace metals (Fe, Mn, Zn, and Cu) by 17–175%, suggesting an improvement in soil nutrients and an increase in productivity. Comparing to the soil in control sites, the TWW irrigation caused a notable increase in the values of IQI-TDS, NQI-TDS, IQI-MDS, and NQI-MDS models ranging 14.6–29.5%, 19.1–25.5%, 21.7–33.3%, and 18.4–23.7%, respectively. This implies that soil quality was ameliorated to a significant extent with TWW irrigation. These improvements resulted in a remarkable increase in corn yield ranging from 12.5% to 28.1%. The regression equations revealed that up to 78%, 47%, 72%, and 36% of the variance in the IQI-TDS, NQI-TDS, IQI-MDS, and NQI-MDS models, respectively, could be captured by corn yield. The results of the regression and correlation analyses showed that the IQI-MDS model was more accurate than the other models in assessing soil quality and predicting crop yield. These findings may be an effective and practical tool for policy making, implementation, and management of soil irrigated with TWW.

A better understanding of the effect of long-term tillage management on soil properties and yield is essential for sustainable food production. This research aimed to evaluate the 37-year impact of different tillage systems and cover cropping on soil hydro-physical properties at 0–15 and 15–30 cm, as well as on soybean [Glycine max (L.) Merr] yield. The long-term experiment was located in Jackson, TN, and the different treatments involved in this study were no-tillage (NT), disk (DP), chisel (CP), moldboard plow (MP), and no-tillage with winter wheat [Triticum aestivum (L.)] cover crop (NTW). Forty-five days after the tillage operation, MP showed a comparable bulk density (BD) with NT, NTW, and CP at 0–15 cm depth. At surface depth, No-tillage systems increased cone penetration resistance (PR) by 12% compared with the reduced tillage systems, and 47% relative to MP. Wet aggregate stability (WAS) at surface depth was 27% and 36% greater for NT systems than for reduced and conventional tillage systems, respectively. Similarly, the geometric mean diameter (GMD) of aggregates was significantly higher under NT and NTW. However, water infiltration and field-saturated hydraulic conductivity (K_fs) did not differ significantly among tillage systems. The greatest soybean yield was obtained from CP and DP, producing 10% higher yield than NTW. Overall, 37 years of no-tillage, with or without simplified cover cropping did not result in a consistent improvement in soybean yield and soil physical properties with the exception of having improved soil aggregation.