Produtividade e rentabilidade de rúcula adubada com espécie espontânea, em duas épocas de cultivo

Abstract

The rocket salad is sensitive to environmental conditions, presenting cycle e cultivation technique similar to coriander in Northeast of Brazil. However, there is little information on organic manuring and cultivation seasons. By research, a specie which occurs spontaneously in the Caatinga has demonstrated its feasibility in Vegetable Crops when incorporated to soil as green manure. Denominated rooster tree, this plant can increase productivity and profitability in cultivating rocket salad, especially in conditions of mild temperatures and reduced photoperiod. Due to the mineralization and immobilization process of the organic matter, the time of soil permanence of the rooster tree influences the availability of nutrients along the crop cycle. This sense, the objective of this research was to evaluate the agronomic performance and profitability in the production of rocket salad cv. Cultivada fertilized with different amounts of rooster tree and times of incorporation of green manure into the soil, in two cultivation seasons (spring-summer and autumn), in the conditions of Serra Talhada, Pernambuco state, Brazil. In both experiments, the experimental design was a randomized block, in factorial 4 x 4, with three replications, with the first factor consisting of quantity of rooster tree (5.4, 8.8, 12.2 and 15.6 t ha-1 on a dry basis), and the second by times of soil incorporation (0, 10, 20 and 30 days before sowing of rocket). The agronomic features evaluated were: plant height, number of leaves per plant, yield of green mass and dry mass. Economic indicators were also determined: gross income, net income, rate of return and profitability index. The homogeneity of variances was accepted for all variables, enabling the execution of a joint analysis of experiments. There was an increase in the productive response of rocket with rise of amount of rooster tree. A synchrony between supply of nutrients by green manure and the period of maximum demand by rocket salad was observed in the incorporation time of 20 days before planting. The close C/N ratio (25/1) of the rooster tree promoted this rapid mineralization of organic matter. Cultivation in autumn increased the cycle of rocket salad, providing greater vegetative growth due to the occurrence of average temperatures near 26 ºC and photoperiod below of 12 hours. The optimal agronomic performance of the rocket fertilized with rooster tree was translated into monetary terms. Expenditures on manpower corresponded on average to 69% of production costs. Due to the increase in the daily rate of rural workers, the costs of preparing the green manure were higher in autumn. The high yield of green mass in autumn allowed net income higher than in the spring-summer. The amount of 12.2 t ha-1 of rooster tree promoted greater profitability for the production of rocket salad. The incorporation of green manure 20 days before planting the crop was considered ideal to the economic viability of the activity. The net income of the rocket was higher in the autumn season.