Effect of Lime, Sulfur, and Molybdenum on N2 Fixation and Yield of Dark Red Kidney Beans1

Abstract

AbstractSymbiotic nitrogen fixation by the Rhizobium‐legume association of fieldbeans does not provide sufficient nitrogen for optimum yield under Michigan growing conditions. Consequently, an average of 44.8 kg/ha (40 lbs/A) of supplemental nitrogen is applied to these legume crops each year. This results in a sizeable investment for the growers and also increases the potential for N loss by leaching and runoff.The purpose of this study was to determine whether lime, S, and/or Mo might be limiting N2 fixation and bean yield of dark red kidney beans (Phaseolus vulgaris L.) in the field. Two acid sandy soils 40.2 km (25 miles) apart, N‐S direction, suspected of being deficient in S and Mo, were selected for this study. Lime rates (0, 2,800, and 5,600 kg/ha), S rates (0 and 45 kg/ha), and Mo rates (0 and .07 kg/ha) were compared in a factorial design. Symbiotic nitrogen fixation was measured by the acetylene reduction assay. Soil samples were collected and bean yields were recorded.Sulfur increased nitrogen fixation (acetylene reduction activity) nearly 60%. The lime and Mo treatments had little influence on nodule activity. The average yield of beans was increased 10% by the 2,800 kg/ha lime rate and 26% by the 5,600 kg/ha lime rate. The Mo seed treatment reduced yield 7%. Yield response to S was 26% at the zero lime rate, 12% at the 2,800 kg/ha lime rate, and 10% at the 5,600 kg/ha lime rate. Soil test results showed that lime increased the amount of available S in the soil.These data suggest that lime and S are limiting bean yield on certain acid sandy soils in Michigan. It also appears that where soils are S deficient symbiotic nitrogen fixation is being restricted.