The use of spontaneous plants of the Caatinga biome as green manure is becoming a viable option for vegetable production in northeastern Brazil. Among these plants, the scarlet starglory is a spontaneous plant adapted to the climatic and soil conditions of the region, with high biomass production, rapid growth and low C/N ratio. We evaluated the agroeconomic performance of carrot (cv. Brasília) depending on added amounts of scarlet starglory under the ground and of its moment of incorporation. The study was carried out in a rural area, in Mossoró, Rio Grande do Norte state, Brazil, from September to December 2009. The experimental design was randomized complete blocks with the treatments arranged in a factorial scheme (4x4) + 1, with three replications. The first factor was comprised of amounts of scarlet starglory placed between the carrot rows, in a depth of 15 cm (5.4, 8.8, 12.2 and 15.6 t ha-1 on a dry basis) and the second factor, of the incorporation moment of this material (0, 15, 30 and 45 days after sowing carrots). The additional treatment (control) was 40 t ha-1 of cattle manure applied 10 days before sowing. We evaluated the marketable and total yield of roots, percentage of the different classes of roots and the economic indicators of gross income, net income, rate of return and profit margin. No significant interaction between the amounts of scarlet starglory under the soil and the incorporation moment was determined in any of the characteristics examined for carrot. The best agroeconomic performance of carrot cropping was obtained by adding 15.6 t ha-1 of scarlet starglory to the soil. The optimization of this performance was achieved with the incorporation moment of 26 days after carrot sowing.
Daucus carota; green manure; agronomic efficiency
