Critical potassium deficiency levels for a grass/ legume pasture grown on soils of the subhumid zone of Nigeria

Abstract

A greenhouse experiment was conducted to determine the critical deficiency levels of potassium (K) in the subhumid zone soils for predicting response of a mixture of Andropogon gayanus and Stylosanthes hamata cv. Verano to K application. Twenty coarse textured soils, having loamy sand to sandy loam textures and with exchangeable K contents ranging from 0.08 to 0.97 cmol/kg, were used. Two rates of K applied were 0 and 80 mg K/kg. Application of K on soils testing less than 0.18 cmol/kg significantly increased the dry matter yields of both Andropogon and stylo tops. Soil K was significantly related to relative yields of Sole Andropogon (r = 0.60**), sole stylo (r = 0.78***), and Andropogon/stylo mixture (r = 0.77***). There was a high correlation between the K concentration in plant tissue and the relative yields of sole Andropogon (r = 0.68**), sole stylo (r = 0.67**), Andropogon in mixture (r = 0.65**), and stylo in mixture (r = 0.64**). The graphical model of Gate and Nelson indicated the critical levels of the available form of K in soil to be 0.18, 0.20, and 0.21 cmol/kg for sole Andropogon, sole stylo and Andropogon/stylo mixture, respectively. The critical levels for K in plant tissues were also determined to be 1.30, 2.03, 1.38 and 1.86% for sole Andropogon, sole stylo Andropogon in mixture, and stylo in mixture, respectively.

Notes

Department of Agronomy, University of Ibadan, Ibadan, Nigeria

International Livestock Centre for Africa (ILCA) Subhumid Research Site, PMB 2248, Kaduna, Nigeria

Corresponding author.