Avaliação de um sistema agroflorestal na região de Itaparica, semiárido pernambucano

Abstract

The objective of this research was to evaluate the economic return and development of four forest crops (two clones of eucalyptus, angico and aroeira) in an agroforestry system with beans, fertilized with two nutrient sources: fish tank residues and sediment of the lake of Itaparica, and the biochar as soil conditioner. The experiment was carried out at the Experimental Station of the Instituto Agronômico de Pernambuco (IPA) in Belém de São Francisco - PE. The heights of all trees were measured every three months until 15 months, and from that period, height and CAP measurements were performed every six months, totaling 36 months. A total of 192 plots were distributed in tree spacing: 3 m x 2 m in monoculture, 4 m x 2 m in monoculture and 4 m x 2 m in a consortium, randomly distributed with 4 replicates, including the control (without fertilization). Each plot had 28 plants, of which 10 occupied the useful area. Fertilization of forest crops with nutrient sources and biochar was carried out during the experiment and a second fertilization was carried out 12 months after the implantation. The cowpea beans was sown at a spacing of 0.80 m x 0.30 m, being planted in the useful area of each plot of the agroforestry system. The multivariate statistical method of repeated measurements was used to analyze the growth in height of forest crops. For the economic analysis of the agroforestry system and the monocultures, the costs and revenues with the production of cowpea throughout the evaluation period of the system were considered, as well as the simulation carried out with the production and sale of firewood and stakes. The sources of nutrients, fish tank residues and sediments from Itaparica lake, contributed significantly to the growth in forest height and cowpea crop, becoming alternatives to be used as biofertilizers in forest and agricultural plantations in the region of Itaparica. Biochar did not present significant results in the development of forest and cowpea crops. The highest height averages for forest crops were reached in the spacing 3 m x 2 m, with 7,62 m at 36 months. The clone MA 2001 presented the highest average height growth for the evaluated eucalyptus clones. Between the native species evaluated, the highest average was verified for the angico. The consortium between native species, angico and aroeira, presented the best results in relation to cowpea bean productivity. Cowpea in monoculture obtained the highest yields and the highest in relation to agroforestry systems. In the economic analysis of the systems evaluated, the combination of “firewood and stakes" provided the highest revenues and was therefore more profitable compared to the sale of only firewood.