Collaboratrices et collaborateurs

CONTEXT: Information on how crop yields are affected by weather variations and extreme weather is needed to develop climate adaptation measures for arable cropping systems. Here, we analysed the effects of weather anomalies and soil texture on crop yield anomalies across Sweden from 1965 to 2020. OBJECTIVE: The aims of this study were to (i) assess the effects of temperature and precipitation anomalies and extreme weather on crop yield anomalies for major field crops across Sweden, (ii) quantify how crop responses to weather anomalies vary along the north-south climate gradient across Sweden, and (iii) elucidate the impacts of soil texture on yield responses to weather anomalies. METHODS: We used daily mean air temperature, daily total precipitation, soil texture and crop yield data from public databases covering all 21 counties in Sweden. Yield data was detrended to account for the effects of agricultural intensification on crop productivity. To assess seasonal weather influences on crop yields, temporal trends of daily average temperature and daily total precipitation were detrended for each season containing a three-month period. We also used a water balance index and a heat wave index to evaluate the impact of extreme weather. RESULTS AND CONCLUSIONS: Our analyses showed that years with extreme weather during summer (i.e. heat waves, drought or water excess) resulted in the largest negative yield anomalies. Spring-sown crops were more negatively affected by extreme weather compared to autumn-sown crops, which we associate with differences in the lengths of the growth period for autumn- and spring-sown crops. Effects of soil texture on yield anomalies were found for spring-sown cereals, where negative effects of drought were exacerbated with increasing sand content. Moreover, we showed that the effects of weather conditions on crop yield anomalies differed between different regions within the country. In northern Sweden, crop yields were more sensitive to excess water, while drought effects were more pronounced in southern Sweden. Similarly, increased summer temperatures favoured crop yields in northern Sweden but had a negative impact on crop yields in the southern part of the country. SIGNIFICANCE: Our study demonstrates that weather impacts on yields vary between crops and locations, and that adaptation to future climate will require crop- and site-specific strategies.