CHANGES IN SOIL FERTILITY, PRODUCTION OF BIOMASS AND NITROGEN BALANCE IN COFFEE AGROFORESTRY SYSTEMS IN NICARAGUA

Abstract

A coffee agroforestry experiment was established in 2001 in the Municipality of Masatepe, Nicaragua; main treatments were legume and non-legume arboreal species with subplots of intensive and moderate use of organic and conventional management of fertility, pests, diseases and weeds. Soil chemical characteristics, mineralization of nitrogen, carbon and microbial biomass were measured in each plot for a composite soil sample. To measure biomass production two trees per plots were pruned and N content determined. The N balance was calculated by determining the extracted N in the coffee berries, firewood production compared to the amount of N contributed by organic and chemical fertilizers. The results show that acidity fell under intensive organic management compared to moderate conventional, while phosphorus, potassium and the microbial biomass were all higher under organic than conventional. The CIC, total N and total C, were all lower in the 2004 with respect to the 2001. In both years there were no statistical differences between the treatments. The rate of mineralization of the N was lower under the sun treatment total with respect to the treatments with arboreal shade; and higher the intensive organic management than conventional management. The amounts of residues produced by pruning are greatest for Inga laurina, nevertheless, in the year when trees were thinned abebuia. rosea it surpasses it. The nitrogen balance was negative for Moderate Conventional and Organic Moderate management under Inga. laurina since the extractions by coffee berries harvest and firewood are superior to the additions of N via fertilization causing an impoverishment of this mineral element in the ground.

DOI: 10.5377/calera.v10i14.22