Effects of nitrogen fertilizer and white clover on dry matter and nitrogen yields of Digitaria decumbens and Setaria sphacelata var. sericea in south-eastern Queensland

Abstract

An experiment was conducted to evaluate yield dynamics of three candidate grasses that could replace Pangola (Digitaria decumbens CPI 18578). The grasses were Digitaria pentzii cn. Nelspruit and Setaria sphacelata var. sericea cvv. Nandi and Kazungula, grown in association with white clover (Trifolium repens), or at three levels of fertilizer nitrogen. Cumulative dry matter yields in t ha-1 taken from nine cuts between August 1965 and January 1967, differed (P< 0.05) as follows. For grasses, Pangola (26) > Kazungula (24) > Nelspruit (22) > Nandi (20); and for associated clover, Pangola (10.5) and Nelspruit (10.5) > Kazungula (6.8) and Nandi (6.7). Pangola and Nelspruit reached peak yields in December, Nandi and Kazungula in April. Clover yields peaked in September and again in December. Clover in Kazungula-clover plots became severely depressed after 14 months. When grown in association with grasses, clover smoothed out peaks and troughs characteristic of infrequent applications of nitrogen fertilizer. Periodicity of nitrogen yields was similar to that of DM yields. Clover produced more DM than either Pangola or Nelspruit. Conversely, clover was severely suppressed by Kazungula, less by Nandi. Except for reservations about Kazungula where grown with clover, any one of the three candidate grasses would be a suitable replacement for Pangola.