Benefits of diverse agriculture on crop yield

Using yield data from multiple long-term experiments (LTEs) covering a period ranging between 20 to 55 years, I first investigated how a specialized cropping system compared with diverse systems and whether a crop-livestock system provided added benefits compared to a stockless diverse system in terms of yield and stability (Paper I). Stockless diversification provided a valid alternative to crop-livestock systems to maintain high yields. Specifically, diverse stockless and crop-livestock systems enhanced winter cereal yield by 15% compared to the specialized system. \nAs a second step, I examined how crop rotation and fertilization affected yield responses in the long-term (Paper II). I found a beneficial effect of diverse crop rotation on cereal yield especially in combination with mineral fertilization. \nI further investigated how cereal yields in contrasting crop rotations responded to past climatic variation, to identify the potential of diverse crop rotation to provide an adaptation to climate change (Paper III). Diversifying crop rotation represents an adaptation strategy for enhancing cereal yields, both at northern latitudes where precipitation and temperature is expected to increase, and at southern latitudes where precipitation is expected to decrease. \nFinally, using soil collected in a LTE, I examined how contrasting crop rotations and soil compaction, a factor known to limit yield, influence the contribution of insect pollination to yield as well as the nitrogen acquisition of faba beans via nitrogen fixing (Paper IV). Insect pollination contributed to seed quality and the combination of crop monoculture and soil compaction reduced the capacity of the legume crop to biologically fix nitrogen. \nIn conclusion, diversification of cropping systems and of the crop rotation offers opportunities to maintain or enhance yield in a changing climate.