Effects of biological and technical subsoil amelioration on root growth and crop performance in cereal crops

For more comprehensive exploration of soil nutrients and water, one option is to promote root growth into the subsoil. As this is limited by subsoil compaction, technical amelioration (deep tillage) may be used to enhance subsoil access. Alternatively, or additionally, deep-rooted crops may form biopores which support deeper root growth of subsequent crops. In the presented study, a field experiment was conducted in Germany to compare and evaluate the effects of biological (2 years continuous cultivation of deep-rooting perennial lucerne as a pre-crop) and technical subsoil amelioration (strip-wise deep tillage combined with subsoil compost application) on root growth and crop performance of cereals. Subsequent spring barley and winter wheat were analysed for shoot biomass, nutrient uptake, crop yield, maximum rooting depth and root length density. Results indicate a positive combined effect of lucerne as pre-crop and deep tillage with compost on root growth in the subsoil as well as shoot growth, nutrient uptake and grain yield of spring barley in a comparatively dry year. However, in the following experimental year with abundant water supply, winter wheat shoot biomass and grain yield were not affected. These results highlight the potential of increasing access to subsoil nutrient and water resources in mitigating impacts of drought. • Biological amelioration was 2 years cultivation of deep-rooting perennial lucerne as pre-crop. • Technical subsoil amelioration was strip-wise deep loosening plus subsoil compost. • Combined effect of lucerne and deep tillage with compost improved subsoil root growth. • Shoot growth and grain yield was improved in spring barley in dry year, but not in winter wheat.