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

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.

摘要 本研究旨在明确以土壤施入不同用量的牛角瓜（roostertree，学名*Calotropis procera* (Ait.) R.Br.）生物质为变量，实现巴西北里奥格兰德州半干旱区豇豆鲜籽粒产量最大化时，对应最大农艺效率与经济效率的施用量。试验于2013年8月至11月在巴西北里奥格兰德州阿拉戈辛哈市的半干旱区联邦农村大学（Universidade Federal Rural do Semi-Árido, UFERSA）“拉斐尔·费尔南德斯”试验农场开展。试验采用完全随机区组设计，设置5次重复。处理组设置为以干物质计的20、35、50及65 t·ha⁻¹的牛角瓜生物质施用量。本试验测定的指标包括：每平方米鲜荚数、鲜荚产量与干质量、每荚鲜籽粒数、百粒鲜籽粒质量，以及鲜籽粒干质量。同时测定了以下经济指标：总营收与净收益、生产运营成本、投资回报率以及利润率。研究结果表明：当土壤施入61.0 t·ha⁻¹牛角瓜生物质时，豇豆鲜籽粒产量达3.05 t·ha⁻¹，此时农艺效率达到最优；当土壤施入53.57 t·ha⁻¹牛角瓜生物质、鲜籽粒产量为3.02 t·ha⁻¹时，净收益可达8701.42巴西雷亚尔（R$），此时经济效率达到最优。在北里奥格兰德州半干旱种植条件下，将牛角瓜作为绿肥应用于鲜食豇豆栽培具备技术经济可行性。