Irrigation

All legumes require regular, uniform watering during the growing season. Wet or waterlogged soils during establishment can limit seed germination, cause root rot problems, and poor or nonuniform stands. Inconsistent watering around flowering can cause misshapen pods, split set, poor seed fill or sizing, and stringy pods. Overwatering encourages root rots and foliar diseases. Sprinklers can be used to germinate seeds, then after the first cultivation, switch to furrow or drip irrigation. For small production areas, use drip irrigation.

Monitor soil water status to maintain consistent, uniform water supply. Use soil moisture monitoring sensors and weather-based irrigation scheduling to monitor plant needs. Place sensors at various locations in the field and at several depths in the soil profile to accurately measure of soil water content. Start irrigating at 20%-25% depletion when irrigating by drip and at 35%-45% depletion for furrow or sprinkler systems. Water extraction estimates using reference evapotranspiration adjusted with a crop coefficient (kc) are closely related to row canopy cover. The kc is about 0.4 for a legume crop with 25% row cover; 0.8 for 50% cover; 1.1 during flowering and pod growth; and 0.8 during the late season seed maturity (dry bean/pea) period. Find low-cost tools and methods to monitor soil water at ATTRA Sustainable Agriculture.