The Effect of Management of Crotalaria juncea green Manure on the Yield and Nitrogen Uptake of Maize

Abstract

In Hawaii, Crotalaria juncea green manure (GM) grown 2 months on an N-deficient soil and incorporated 1 month before sowing hybrid maize yielded 121 kg/ha Nin 5.8 t above-ground dry matter (tops) and resulted in maize yields equivalent to those obtained with 150 kg/ha urea N (N150). Tops alone (G) at rates of up to 180 kg/ha N were not as effective as GM but were equivalent to N100 ; low rates of tops (under 100 kg/ha N) were equivalent to similar urea rates. The below-ground GM component (green manure residue, GMR) provided rapidly available N and produced maize yields similar to N100, G120 and G180 • Application of tops as mulch was inferior to burial in soil. Response to urea was linear and significant between all rates. Combined GMR and G120 maize yields were greater than responses to GM. Results of intercropping maize with C. juncea and Sesbania cannabina were also reported. A second crop comparing residual effects with urea reapplications found significant maize yield responses to applied N but did not show strong differences in residual value among previously applied urea and legume N treatments.