Limited capability of organic farming and conservation tillage to enhance agroecosystem resilience to severe drought

Abstract

CONTEXT: Climate change increasingly threatens food security, particularly through prolonged phases of drought. It is therefore important to evaluate and develop arable cropping systems with an enhanced capability to withstand severe drought events to ensure food production. However, it is still poorly understood whether specific management strategies, in particular organic farming and conservation tillage that are thought to be more resilient to drought, can enhance the ability of agroecosystem to withstand drought.OBJECTIVE: The main objective of this study was, therefore, to test the ability of organic farming and conservation tillage practices to withstand drought within expected boundaries of climate scenarios for the end of the century.METHODS: This study summarizes the effects of drought (both natural and experimental) on the productivity of three arable crops (maize, pea-barley mixture and winter wheat) assessed in three consecutive years in a long-term cropping system field experiment. We tested whether four relevant cropping systems (i.e., conventional and organic with and without soil conservation tillage) differ in their ability to reduce the impact of drought on plant yield and crop performance. We studied conditions of moderate natural drought (summer 2018) and severe experimental droughts using rainout shelters (3 years) after 8 years of contrasting field management.RESULTS AND CONCLUSIONS: We found pronounced and consistent yield reductions due to experimental drought events for all cropping systems (34% for maize, 23% for pea-barley, and 17% for winter wheat). Drought induced yield reductions were largely similar across the four cropping systems, suggesting very limited capacity of any cropping system to buffer severe drought. Yet, there was an obvious but insignificant trend in maize in 2018 where under moderate and experimental drought conservation tillage resulted in a higher on-average yield compared to the plowed systems. Furthermore, drought resulted in lower nitrogen (N) uptake by the crops and a positive N budget, which could result in higher N losses after a drought period.SIGNIFICANCE: This study demonstrates that drought has consistent and adverse effects on crop productivity under conventional, organic and soil conservation arable cropping. It further demonstrates that it is difficult to find effective adaptation strategies for arable systems under realistic future scenarios and underlines the need to combine all available practices, from soil management to crop and cultivar choice, to mitigate drought impacts on crop productivity.