Agronomic and Economic Response of Three Tropical Legumes to Lime and Phosphorus in an Acid Infertile Spodosol1

Abstract

AbstractNumerous potential benefits have been cited for the inclusion of tropical legumes in pastures, but few commercial successes have been realized. Information is needed on even the most basic aspects of tropical legume culture. The study herein was designed to determine rates of lime and P for maximum yield of three tropical legumes, and to estimate the rates resulting in maximum economic return under field conditions. An acid infertile Spodosol was amended with lime up to 4000 kg ha−1 and P up to 80 kg ha−1. Equations relating herbage yield during the first 2 years of growth to rates of lime and P were developed. All three legumes (Aeschynomene americana L., Macroptilium atropurpureum Urb., and Desmodium heterocarpon DC.) responded positively to both lime and P. Maximum yield of Desmodium was obtained at lime and P rates of 2740 and 75 kg ha−1, respectively. Maximum calculated herbage yields of Aeschynomene and Macroptilium were obtained at lime and P rates somewhat in excess of maximum treatment levels. An economic analysis that considered hay as the produced product revealed that maximum economic returns occurred at lime and P rates only slightly lower than those for maximum yield. Considering protein as the product, for all three legumes lime and P rates of approximately 3000 and 75 kg ha−1 produced maximum yield and maximum economic return.