Utilização agroecológica de fibra de coco (Coccus Nucifera l.) Verde para melhoria da produção de Alface (Lactuca sativa L.) Cv. Rafaela

Abstract

Organic culture of lettuce (Lactuca sativa L.) with green coconut fiber (Coccus nucifera L.), in natura. This agricultural by-product is an ambiental degradation as a result of its diffuse distribution and high decomposition time. The coconut fiber was processed in a crushing machine and added with hen manure (4% v/v) in the ratios of 0, 10, 20 and 30% by comparing it with the pure soil and the soil with 20% of fiber until the depth of 20 cm, each one with four repetitions to verify a possible improvement of the fresh mass, dry mass, the foliar area and the diameter of the plants. The experiment was carried through in two stages: (i) in the greenhouse of UEMA, in vases of 4L, and (ii) under field conditions, in a small farm in the city of Paço de Lumiar, Maranhão, in seedbeds of 36 plants each. The two experiments soils were from this small farm. This soil which has not been submitted to any previous culture is classified as oxysoil, presented 36 g dm-3 of organic matter (OM) and bases addition (BA) of 30,4, low potassium rate (0,035 g kg-1), and reasonable rates of calcium (0,38 g kg-1) and magnesium (0,12 g kg-1), and critical values of phosphorus (2 mg dm-3), for the texture between loam and silty-loam presented. The pH value of 5,4 is classified as good and may have been slightly acidified by the irrigation water with a pH of 4,6. The low mineralization rates explain the low electrical conductivity, of 0,06 mS cm-1. This soil was enriched with hen manure with a high concentration of OM (483,5 g kg-1) and C/N relation of 12,5, and with green coconut fiber with expressive amounts of calcium, magnesium and potassium (4,58; 2,21 and 1,27 g kg-1). In general, the treatments with 20% and 30% of fiber had better results in both cases. The statistical design employed was the DMS (minimum difference significative) with 5% of probability. We conclude that the utilization of the green coconut fiber is a factor of optimization for the culture of lettuce in organic conditions.