AGRO-ECONOMIC EFFICIENCY OF THE INTERCROPPING OF CARROT X COWPEA-VEGETABLE UNDER DIFFERENT SPATIAL ARRANGEMENTS AND POPULATION DENSITIES

ABSTRACT The objective of this study was to evaluate the agro-economic efficiency of the intercropping of carrot with cowpea-vegetable under different spatial arrangements and population densities in the semi-arid conditions of the Brazilian Northeast. The study was conducted at the "Rafael Fernandes" Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA) during the period July 2013 to February 2014. The experimental design was of randomized complete blocks with four replications and treatments arranged in a 3 × 4 factorial scheme, where the first factor consisted of spatial arrangements (2:2; 3:3 and 4:4) and the second factor by population densities of cowpea-vegetables (100, 80, 60 and 40% of the recommended population in sole crop [RPSC]). All treatments were fertilized with roostertree (Calotropis procera [Ait.] R.Br.), which is a spontaneous species of the Caatinga biome. The indices of agronomic efficiency of the intercropping systems assessed were: land equivalent ratio, productive efficiency index and score of the canonical variable. The following economic indicators were also evaluated: gross income, net income, rate of return and profit margin. The agro-economic efficiency of the intercropping system of carrot with cowpea- vegetable was influenced by the spatial arrangements, with the 2:2 arrangements standing out from the others. The greatest agro-economic efficiency of the intercropping of carrot with cowpea-vegetable was obtained in the population density of 100% of the RPSC when the value of the productive efficiency index was 0.75.摘要 本研究旨在评估巴西东北部半干旱条件下，胡萝卜与菜用豇豆间作在不同空间配置与种群密度下的农业经济效率。本试验于2013年7月至2014年2月期间，在巴西半干旱区联邦农村大学（Universidade Federal Rural do Semi-Árido，UFERSA）的“拉斐尔·费尔南德斯”试验农场开展。试验采用随机完全区组设计，设置4次重复，处理采用3×4因子排列方案：第一因子为空间配置（2:2、3:3与4:4），第二因子为菜用豇豆种群密度（为单作推荐种群密度（Recommended Population in Sole Crop，RPSC）的100%、80%、60%与40%）。所有处理均施用牛角瓜（Calotropis procera [Ait.] R.Br.）制成的肥料，该物种为卡廷加（Caatinga）生物群系的本土自发物种。本研究评估的间作系统农艺效率指标包括：土地当量比、生产效率指数及典范变量得分。同时评估了以下经济指标：总收入、净收入、收益率及利润率。结果表明，胡萝卜与菜用豇豆间作系统的农业经济效率受空间配置影响，其中2:2配置表现最优。当生产效率指数为0.75时，采用单作推荐种群密度100%的处理，可获得胡萝卜与菜用豇豆间作系统最高的农业经济效率。