Nitrogen and molybdenum uptake and dry matter relationships of soybeans and forage legumes in response to applied molybdenum on acid soil

Increased emphasis on biological fixation of N has resulted in increased soybean acreage and establishment of legumes for pastures in the Southeastern United States. Many of the soils in this region are acid and therefore may be marginal in available Mo, which is involved in symbiotic N fixation by legumes. A greenhouse experiment was conducted to determine relative response to applied Mo of two cultivars of soybeans and six species of forage legumes on acid and limed soil. Decatur sil (Rhodic Paleudult), at pH 5 and limed to pH 6 and 7, was fertilized with 0 and 2 ppm of Mo, P, K, and a micronutrient mixture minus Mo, inoculated with appropriate rhizobia, and seeded to legumes. Soybean tops were harvested after 6 weeks and three clippings of the forage legumes were made after 6, 9, and 13 weeks’ growth. Dry forage yields of all species increased with soil pH level without applied Mo. Soil application of Mo resulted in increased growth and uptake of N and Mo of most species at pH 5. Crop response...