Field beans are an indeterminate crop, thus producing flowers, pods and seed over a period of time throughout crop development whilst vegetative growth is continuing. This may be a benefit to a crop that is sensitive to drought so that later formed pods may compensate for poor growth of earlier produced pods. Temperature is the main determinant of crop development and determines the duration of each developmental phase. However, high temperatures may be linked with drought conditions, which shorten developmental periods and may reduce yield.
The response of field beans to soil moisture may explain why soil conditions are an important determinant of yield. Research at Nottingham University during the 1980’s showed that crops established in compacted soils develop small, shallow root systems that exploit a smaller volume of soil and take up less water than those grown in a well structured soil. Yields were reduced by up to 15% in experiments over a number of seasons. Winter beans are suited to soils with good water holding capacity and generally yield better in heavy clays than on light, drought prone land.