The maintenance of soil health in agro-ecosystems is essential for sustaining agricultural productivity. Through its positive impacts on various soil physical and biological processes, cover cropping can be an important component of sustainable agricultural production systems. However, the practice of cover cropping can be complex, and possible trade-offs between the benefits and side effects of cover crops have not been examined. To evaluate these benefits and potential trade-offs, we quantitatively synthesized different ecosystem services provided by cover crops (e.g., erosion control, water quality regulation, soil moisture retention, accumulation of soil organic matter and microbial biomass, greenhouse gas (GHG) emission, weed and pest control, as well as yield of the subsequent cash crop) using data from previous publications. We used a simple indicator (δ), defined as the ratio of an observed variable (i.e., ecosystem service) under cover crop and under fallow condition, to evaluate the impacts of cover crops on a given ecosystem service. Our results showed that cover crops provided beneficial ecosystem services in most cases, except for an increase in GHG emission (δCO2 = 1.46 ± 0.47 and δN2 O = 1.49 ± 1.22; x ¯  ± SD) and in pest (nematode) incidence (δnematode abundance = 1.29 ± 1.61). It is also important to highlight that, in some cases, tillage could offset the extent of ecosystem service benefits provided by cover crops. Based on this synthesis, we argue that cover crops should be incorporated into modern agricultural practices because of the many environmental benefits they offer, particularly the maintenance of soil and ecosystem health. More importantly, there was generally an increase in cash crop yield with cover cropping (δyield = 1.15 ± 0.75), likely due to improvement in various soil processes. Despite its benefits, the complexity of cover crop management should not be overlooked, and site-specific factors such as climate, soil type, cover crop species and tillage practices must be considered in order to optimize the benefits of cover cropping. In addition to crop yield, detailed economic analyses are needed to calculate the direct (e.g., reduction in the amount of chemical fertilizer) and indirect monetary benefits (e.g., the improvement of soil quality) of cover crops. Such a comprehensive analysis could serve as incentive for producers to integrate cover crops into their management practices.

Quantitative synthesis on the ecosystem services of cover crops

Variations in the rainfall distribution during the growing season are a major limiting factor restricting the spring maize yield on the semiarid Loess Plateau of China. Conservation tillage can improve yield and water use efficiency but the specific effects of conservation tillage with differing rainfall distributions during the growing season remain unclear. Therefore, a 12-year experiment was conducted and the data were divided into two categories based on rainfall distribution type. If poor rainfall occurred during the jointing-tasseling stage of the maize growing season and adequate rainfall occurred in the filling-maturity stage, the rainfall was named type-A. In contrast, if adequate rainfall occurred in the jointing-tasseling stage and poor rainfall occurred in the filling-maturity stage during the maize growing season, the rainfall distribution was categorized as type-B. This research used conventional tillage (CT) as a control to study the productivity of no-tillage (NT) and subsoiling (ST) under the selected rainfall distributions. The results showed that the type-B rainfall distribution increased dry matter accumulation, yield, soil water use efficiency (WUE) and precipitation use efficiency (PUE) by 18.9%, 32.0%, 21.7% and 45.1%, respectively, when compared with the type-A rainfall distribution. However, under type-A rainfall distribution, NT increased soil water storage by 3.7% and 4.4% and ST increased the soil water storage by 6.0% and 7.0% in the tasseling and grain filling stages, respectively, compared with CT. Moreover, NT and ST increased the dry matter accumulation, yield, WUE and PUE. The relationships among the yield, soil water storage and precipitation showed that the water storage in the sowing stage indirectly affected the maize yield through soil water storage at the tasseling stage, and the increase in precipitation from the jointing to tasseling stages had a directly positive effect on the increase in yield. Based on soil water storage with a value of 202.3 mm in the 0–200 cm soil depth during the tasseling stage, the yield increased by 47.8 kg ha−1 as the soil water storage improved by 1 mm. In conclusion, no-tillage and subsoiling improved the soil water conditions, mitigated the soil drought stress caused by variable rainfall distribution and improved the yield. Therefore, no-tillage and subsoiling practices are recommended for agricultural production in semiarid areas.

Conservation tillage improves soil water storage, spring maize (Zea mays L.) yield and WUE in two types of seasonal rainfall distributions

Variations in the rainfall distribution during the growing season are a major limiting factor restricting the spring maize yield on the semiarid Loess Plateau of China. Conservation tillage can improve yield and water use efficiency but the specific effects of conservation tillage with differing rainfall distributions during the growing season remain unclear. Therefore, a 12-year experiment was conducted and the data were divided into two categories based on rainfall distribution type. If poor rainfall occurred during the jointing-tasseling stage of the maize growing season and adequate rainfall occurred in the filling-maturity stage, the rainfall was named type-A. In contrast, if adequate rainfall occurred in the jointing-tasseling stage and poor rainfall occurred in the filling-maturity stage during the maize growing season, the rainfall distribution was categorized as type-B. This research used conventional tillage (CT) as a control to study the productivity of no-tillage (NT) and subsoiling (ST) under the selected rainfall distributions. The results showed that the type-B rainfall distribution increased dry matter accumulation, yield, soil water use efficiency (WUE) and precipitation use efficiency (PUE) by 18.9%, 32.0%, 21.7% and 45.1%, respectively, when compared with the type-A rainfall distribution. However, under type-A rainfall distribution, NT increased soil water storage by 3.7% and 4.4% and ST increased the soil water storage by 6.0% and 7.0% in the tasseling and grain filling stages, respectively, compared with CT. Moreover, NT and ST increased the dry matter accumulation, yield, WUE and PUE. The relationships among the yield, soil water storage and precipitation showed that the water storage in the sowing stage indirectly affected the maize yield through soil water storage at the tasseling stage, and the increase in precipitation from the jointing to tasseling stages had a directly positive effect on the increase in yield. Based on soil water storage with a value of 202.3 mm in the 0–200 cm soil depth during the tasseling stage, the yield increased by 47.8 kg ha−1 as the soil water storage improved by 1 mm. In conclusion, no-tillage and subsoiling improved the soil water conditions, mitigated the soil drought stress caused by variable rainfall distribution and improved the yield. Therefore, no-tillage and subsoiling practices are recommended for agricultural production in semiarid areas. 

Soils form the basis for agricultural production and other ecosystem services, and soil management should aim at improving their quality and resilience. Within the SoilCare project, the concept of soil-improving cropping systems (SICS) was developed as a holistic approach to facilitate the adoption of soil management that is sustainable and profitable. SICS selected with stakeholders were monitored and evaluated for environmental, sociocultural, and economic effects to determine profitability and sustainability. Monitoring results were upscaled to European level using modelling and Europe-wide data, and a mapping tool was developed to assist in selection of appropriate SICS across Europe. Furthermore, biophysical, sociocultural, economic, and policy reasons for (non)adoption were studied. Results at the plot/farm scale showed a small positive impact of SICS on environment and soil, no effect on sustainability, and small negative impacts on economic and sociocultural dimensions. Modelling showed that different SICS had different impacts across Europe—indicating the importance of understanding local dynamics in Europe-wide assessments. Work on adoption of SICS confirmed the role economic considerations play in the uptake of SICS, but also highlighted social factors such as trust. The project’s results underlined the need for policies that support and enable a transition to more sustainable agricultural practices in a coherent way.

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Tiago Stumpf da Silva

Papers

Long-term soil quality effects of soil and crop management in organic and conventional arable cropping systems

Soil pore characteristics and gas transport properties of a no-tillage system in a subtropical climate