Exploratory experiment on fertilization of six tropical legumes on dark-red latosol from a "cerrado" area

Abstract

A greenhouse experiment was carried out to investigate nutrient deficiencies which restrict the development of six tropical legumes on a dark-red latosol from a "cerrado" area. The legumes were: Glycine javanica L. (common var.), Glycine javanica L. (tinaroo var.), Phaseolus atropurpureus DC. (siratro), Pueraria javanica Benth (tropical kudzu), Centrosema pubescens Benth and Stylosanthes gracilis H.B.K (IRI 1022), S. gracilis was tested of two pH levels to verify the acidity effect on its growth. Both dry matter production of legumes and nodule production increased with phosphorus fertilization. There was no difference in total nitrogen accumulation by plants, when the treatments without phosphorus and complete (all nutrients included) were compared. Dry matter production and nitrogen fixation were not affected by the omission of potassium, sulfur or micronutrients. Both symbiotic nitrogen fixation and dry matter production in the legumes decreased with the absence of liming, althrough average number and weight of nodules were not affected in relation to the complete treatment. Mineral nitrogen application increased nitrogen and dry matter production, but number and weight of nodules were reduced in all the legumes. This nitrogen application resulted in complete inhibition of nodule production on both common and Tinaroo perennial soybeans. The application of two levels of lime did not affect significantly S. gracilis.