Biomass production and chemical composition of Moringa oleifera under different planting densities and levels of nitrogen fertilization

The effect of different planting densities (100,000 and 167,000 plants ha−1) and levels of nitrogen fertilization (0, 261, 521, and 782 kg N ha−1 year−1) on biomass production and chemical composition of Moringa oleifera was studied in a split-plot design with four randomized complete blocks over 2 years with eight cuts year−1 at the National Agrarian University farm in Managua, Nicaragua (12°09′30.65″N, 86°10′06.32″W, altitude 50 m above sea level). Density 167,000 plants ha−1 produced significantly higher total dry matter yield (TDMY) and fine fraction yield (FFDM), 21.2 and 19.2 ton ha−1 respectively, compared with 11.6 and 11 ton ha−1 for 100,000 plants ha−1. Growth rate in 167,000 plants ha−1 was higher than in 100,000 plants ha−1 (0.06 compared with 0.03 ton ha−1 day−1). Average plant height was 119 cm irrespective of planting density. Fertilization at the 521 and 782 kg N ha−1 year−1 levels produced the highest TDMY and FFDM in both years of the study and along all cuts. The interaction between cut and year was significant, with the highest TDMY and FFDM during the rainy season in the second year. Chemical composition of fractions showed no significant differences between planting densities. Significantly higher crude protein content was found in the coarse fraction at fertilizer levels 521 and 782 kg N ha−1 year−1 (87.9 and 93.7 g kg−1 DM) compared with lower levels. The results indicate that Moringa can maintain up to 27 ton ha−1 dry matter yield under dry tropical forest conditions over time at a planting density of 167,000 plants ha−1 if the soil is regularly supplied with N at a level of approximately 521 kg ha year−1 in conditions where phosphorus and potassium are not limiting.