The influence of potassium supply on competition between Nandi setaria and Greenleaf desmodium

Abstract

The influence of potassium level on the growth of a Setaria anceps-Desmodium intortum mixture was studied in the glasshouse using a technique designed to allow or prevent association of the roots of the two species without initially altering above-ground relations. On an infertile, lateritic podzolic soil with all nutrients except potassium and nitrogen added, the yields of desmodium were significantly reduced when its roots were in association with those of setaria. Since this effect did not occur when potassium was added to the system or when their root systems were separated, the results are interpreted in terms of the superior competitive ability of setaria for potassium ; the mechanism involved remains uncertain.