TECHNICAL-ECONOMIC EFFICIENCY OF THE YIELD OF GREEN GRAINS OF COWPEA FERTILIZED WITH ROOSTERTREE

<div><p>ABSTRACT This study aimed to determine the doses of maximum agronomic and economic efficiency as a function of different amounts of roostertree [Calotropis procera (Ait.) R.Br.] biomass added to the soil, that results in the maximum yield of green grains of cowpea in the semi-arid of Rio Grande do Norte state, Brazil. The experiment was conducted at the “Rafael Fernandes” Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Alagoinha, RN, from August to November 2013. In the experiment was used a randomized completely block design with 5 replicates. The treatments consisted of 20, 35, 50, and 65 t ha-1 (on a dry matter basis) of roostertree biomass added to the soil. The evaluated characteristics were: number of green pods per m2, productivity and dry mass of green pods, number of green grains per pod, weight of 100 green grains, and dry mass of green grains. The following economic indicators were determined: gross and net incomes, production operational costs, rate of return, and profit margin. The maximum agronomic efficiency of the yield of cowpea green grain was reached at the yield of 3.05 t ha-1, using 61.0 t ha-1 of roostertree biomass in the soil. The maximum economic efficiency yielded a net income of R$ 8,701.42, at the production of 3.02 t ha-1 green grains with 53.57 t ha-1 of roostertree biomass added to the soil. The use of roostertree as a green manure presents technical-economic feasibility in cowpea cultivation for green grains in the semi-arid conditions of Rio Grande do Norte.</p>