Field response of three subtropical pasture legumes to lime, P and K on an acid sandy soil

Abstract

A field study was undertaken to determine the response of Macroptilium atropurpureum cv. Siratro, Stylosanthes guianensis CM. Oxley and Aeschynomene falcata cv. Bargoo to lime P and K on an acid soil, very low in minerals. The trial extended over four seasons. Significant yield differences between species occurred in all seasons. Although the soil was very acid (c. pH 4,0 in KCI), neither P nor lime application had any significant effect an DM production. A potassium treatment, which was introduced in the last season of the trial, resulted in a significant increase in DM production. The average DM yields of Siratro, Oxley and Bargoo for the four seasons were 5 780, 5 510 and 4 410 kg ha⁻¹, respectively. Analyses for P, K, Ca and Mg showed that plant mineral content was hardly influenced by lime and P applications. Significant differences in mineral content did, however, occur between species. It was concluded that Siratro, Oxley and Bargoo can be grown on soils of inherently low fertility and high acidity without much expenditure on soil amendments, and that these legumes contained sufficient minerals to meet ruminant nutritional requirements.