Nutritional factors limiting growth of tropical forage species in two soils from "zona da mata", MG. I. Red-Yellow latosol

Abstract

Two experiments were undertaken concurrently in a glasshouse to identify the nutritional factors which limit the growth of molasses grass (Melinis minutiflora Beauv.) and Centrosema pubescens Benth, in a Red-Yellow Latosol. A subtractive technique was used to compare the effect of the omission of: lime, N, K, S, Ca, Mg and micronutrients, against a complete nutrient control. A basal P application was made of 150 kg P₂O₅/ha. Both experiments were harvested twice. Molasses-grass growth was seriously limited in the absence of calcium, and symptoms of calcium deficiency were observed in both growth periods. In addition, K deficiency in the two growth periods, and N deficiency in the second one, also limited molasses-grass growth. The omission of micronutrients or S had no detrimental effect on the grass growth. Nodulation and growth of C. pubescens were practicaly inhibited in the simultaneous absence of soil acidity amendment and Ca + Mg (as sulphate). The application of Ca + Mg to the noncorrected soil increased yield and nodulation only slightly. The omission of K, S or micronutrients had no effect on nodulation or growth of the leguminous plant. However, micronutrients contributed to increase N concentration in tops of Centrosema in the second harvest.