Effect of Climate, Crop Protection, and Fertilization on Disease Severity, Growth, and Grain Yield Parameters of Faba Beans (Vicia faba L.) in Northern Britain: Results from the Long-Term NFSC Trials

Faba beans are one of the most suitable grain legume crop for colder, maritime climates. However, there is limited information on the effect of changing from conventional to organic production methods and potential impacts of global warming on the health and performance of faba bean crops in Northern Europe. We therefore assessed the performance of faba beans grown with contrasting crop protection (with and without pesticides) and fertilization (with and without P and K fertilizer input) regimes used in organic and conventional production in seven growing seasons. Conventional crop protection and fertilization regimes had no effect on foliar disease severity, but resulted in small, but significant increases in faba bean yields. The overall yield gap between organic and conventional production regimes was relatively small (similar to 10%), but there was substantial variation in yields between growing seasons/years. Redundancy analysis (RDA) showed that climate explanatory variables/drivers explained the largest proportion of the variation in crop performance and identified strong positive associations between (i) temperature and both straw and grain yield and (ii) precipitation and foliar disease severity. However, RDA also identified crop protection and variety as significant explanatory variables for faba bean performance. The relatively small effect of using P and K fertilizers on yields and the lack of a measurable effect of fungicide applications on foliar disease severity indicate that the use of these inputs in conventional faba beans may not be economical. Results also suggest that the yield gap between organic and conventional faba bean production is significant, but smaller than for other field crops.