European long-term field experiments: knowledge gained about alternative management practices

Alternative management practices such as no-tillage compared to conventional tillage are expected to recover or increase soil quality and productivity, even though all of these aspects are rarely studied together. Long-term field experiments (LTEs) enable analysis of alternative management practices over time. This study investigated a total of 251 European LTEs in which alternative management practices such as crop rotation, catch crops, cover crops/green manure, no-tillage, non-inversion tillage and organic fertilization were applied. Response ratios of indicators for soil quality, climate change and productivity between alternative and reference management practices were derived from a total of 260 publications. Both positive and negative effects of alternative management practices on the different indicators were shown and, as expected, no alternative management practice could comply with all objectives simultaneously. Productivity was hampered by non-inversion tillage, FYM amendments and incorporation of crop residues. SOC contents were increased significantly following organic fertilizers and non-inversion tillage. GHG emissions were increased by slurry application and incorporation of crop residues. Our study showed that alternative management practices beneficial to one group of indicators (e.g. organic fertilizers for biological soil quality indicators) are not necessarily beneficial to other indicators (e.g. increase of crop yields). We conclude that LTEs are valuable for finding ways forward in protecting European soils as well as finding evidence-based alternative management practices for the future; however, experiments should focus more on biological soil quality indicators as well as GHG emissions to enable better evaluation of trade-offs and mutual benefits of management practices.