Opportunities for Mitigating Soil Compaction in Europe—Case Studies from the SoilCare Project Using Soil-Improving Cropping Systems

Abstract

Soil compaction (SC) is a major threat for agriculture in Europe that affects many ecosystem functions, such as water and air circulation in soils, root growth, and crop production. Our objective was to present the results from five short-term (<5 years) case studies located along the north–south and east–west gradients and conducted within the SoilCare project using soil-improving cropping systems (SICSs) for mitigating topsoil and subsoil SC. Two study sites (SSs) focused on natural subsoil (˃25 cm) compaction using subsoiling tillage treatments to depths of 35 cm (Sweden) and 60 cm (Romania). The other SSs addressed both topsoil and subsoil SC (˃25 cm, Norway and United Kingdom; ˃30 cm, Italy) using deep-rooted bio-drilling crops and different tillage types or a combination of both. Each SS evaluated the effectiveness of the SICSs by measuring the soil physical properties, and we calculated SC indices. The SICSs showed promising results—for example, alfalfa in Norway showed good potential for alleviating SC (the subsoil density decreased from 1.69 to 1.45 g cm−1) and subsoiling at the Swedish SS improved root penetration into the subsoil by about 10 cm—but the effects of SICSs on yields were generally small. These case studies also reflected difficulties in implementing SICSs, some of which are under development, and we discuss methodological issues for measuring their effectiveness. There is a need for refining these SICSs and for evaluating their longer-term effect under a wider range of pedoclimatic conditions.

Soil-Improving Cropping Systems for Sustainable and Profitable Farming in Europe

“…Soil compaction: Subsoiling is a means to alleviating compaction [112] by breaking up the compaction of deeper soil layers. In a Romanian experiment, subsoiling was suggested to a depth of 60 cm every 3 to 4 years to improve the aggregate stability and hydraulic conductivity and reduce the soil bulk density while maintaining a good crop yield.…”

Do Agricultural Advisory Services in Europe Have the Capacity to Support the Transition to Healthy Soils?

“…SHM is underpinned by the following management principles identified in the SoilCare project: integrate crop rotation, maintain continuous soil cover, build organic matter, minimise soil disturbance, prevent soil compaction, manage water for soil, use soil-friendly weed/pest control and consider landscape-scale management. These were derived by scientific review [52] and experimentation [53], as documented in this Special Issue, and have proven soil health benefits [54,55]. The focus of this study is on Characteristics of the system of agricultural advisory services (C in blue in Figure 1) and the implications for SHM.…”

The Effects of Soil Improving Cropping Systems (SICS) on Soil Erosion and Soil Organic Carbon Stocks across Europe: A Simulation Study

“…The SoilCare project (https://www.soilcare-project.eu/ (accessed on 12 April 2022) [24]) aimed to identify and evaluate promising soil improving cropping systems and agronomic techniques that increase the profitability and sustainability of agriculture across Europe. In addition to field trials [50,51], the project used a modelling approach to upscale the effects of SICS to EU scale, in a spatially explicit way. To ensure that sufficient healthy food for expanding human populations can be grown within planetary boundaries [52], soil management should aim at improving the health and resilience of land and soil [8].…”

“…Compaction alleviation: reduced use of heavy machinery, preventing soil compaction and therefore improving soil water holding capacity and rooting depth [51,83].…”