Sustainability of carrot-cowpea intercropping systems through optimization of green manuring and spatial arrangements

One of the biggest challenges in intercropping of two or more crops is to maintain their productivity as that of their sole counterparts. In order to obtain sustainable intercropping systems in a semi-arid environment, this study evaluated the agro-economic advantage and sustainability of intercropped systems of carrot and cowpea, optimizing the green manuring and spatial arrangements. Experiments were conducted in the period from July to October 2017 and 2018, using a randomized complete block design with the treatments arranged in a 4 x 3 factorial scheme, with four replications. Treatments included four amounts of M. aegyptia incorporated into the soil (20, 35, 50, and 65 t ha-1 on dry basis) with three spatial arrangements (2:2, 3:3, and 4:4) between the components cultures formed from cowpea rows alternated with carrot rows. The agro-economic advantage indices evaluated in the intercropping systems were: land equivalent ratio (LER), area-time equivalent ratio (ATER), score of the canonical variable (Z), actual yield loss (AYL), intercropping advantage (IA), gross income (GI), net income (NI), rate of return (RR), and profit margin (PM). The highest agro-economic advantages of the carrot and cowpea intercropping were obtained for LER, ATER, NI, and RR of 2.60, 4.16, US$ 8,720.99 ha-1, and US$ 2.21, respectively, for M. aegyptia biomass amounts of 46.42, 47.82, 32.60 and 31.51t ha-1 added to the soil. The 2: 2 spatial arrangement was the one with the best productive performance, with higher net income and rate of return in the intercropping of carrot-cowpea. RESUMO: Um dos maiores desafios no consórcio de duas ou mais culturas é manter sua produtividade como a de suas únicas contrapartes. Com o objetivo de obter sistemas de consórcio sustentáveis em ambiente semiárido, este estudo avaliou vantagem agroeconômica e a sustentabilidade de sistemas consorciados de cenoura e feijão-caupi, otimizando a adubação verde e os arranjos espaciais. Experimentos foram conduzidos no período de julho a outubro de 2017 e 2018, em delineamento de blocos ao acaso, com os tratamentos dispostos em esquema fatorial 4 x 3, com quatro repetições. Os tratamentos incluíram quatro quantidades de M. aegyptia incorporadas ao solo (20, 35, 50 e 65 t ha-1 em base seca) com três arranjos espaciais (2: 2, 3: 3 e 4: 4) entre as culturas componentes formadas a partir de fileiras de feijão-caupi alternadas com fileiras de cenoura. Os índices de vantagem agroeconômica avaliados nos sistemas