Residual Effect of Green Manure with Different Grass/Legume Ratios on the Sequential Cultivation of Broccoli and Brachiaria

The objective of this research was to examine how the same amount of N provided by pure or mixture composition of legume and grass affects the growth and yield of the first following crop (broccoli) and two more subsequent crops (broccoli and brachiaria grass). The first broccoli crop was fertilized with jack bean (JB) and pearl millet (PM) in the following proportions (%): control, 100JB, 75JB25PM, 50JB50PM, 25JB75M, and 100PM. The treatment residual effect was measured on a second broccoli crop and brachiaria grass, with no addition of fertilizer. Biochemical metabolism, canopy area, dry matter production, fresh matter yield, and nitrogen (N) accumulation were evaluated. In broccoli crops (first and residual), higher canopy area, fresh matter yield, dry matter, N accumulation, protein, and amino acid concentrations were detected with 100JB and 75JP25PM compared to the control. In the third crop (brachiaria grass), a greater residual effect on the dry matter and N accumulation were obtained with 25JB75PM and 100PM compared to the control. Protein, amino acids, growth, yield, dry matter production, and N accumulation reached the highest values in two successive broccoli crops when fertilized with mixtures with a higher proportion of JB. A higher residual effect is obtained in brachiaria grass fertilized with higher proportion of pearl millet.