ABSTRACT In this study, the objective was to determine the post-harvest indexes of arugula leaves and beet roots in intercropping under a biomass mixture of different green manures at diverse arugula population densities in two cropping seasons in a semi-arid environment. The experimental design was a randomised complete block design, with treatments arranged in a 4 × 4 factorial scheme with four replications. Treatments consisted of the combination of equitable amounts of Merremia aegyptia and Calotropis procera biomass (20, 35, 50 and 65 t ha-1 on a dry basis) and arugula population densities (400,000, 600,000, 800,000 and 1,000,000 plants ha-1). The characteristics evaluated in the arugula culture were titratable acidity, pH, and soluble solid and total soluble sugar content. In the beet crop, the same characteristics were evaluated in arugula, in addition to the betalain concentration and the internal colour parameters of the tuberose roots. Arugula showed the best post-harvest indexes when fertilised with green manure biomass amounts of 20, 20 and 65 t ha-1 at a population density of 1,000,000 plants ha-1, while beet showed the best indices with green manure amounts of 65, 41, 36 and 40 t ha-1 with an arugula density of 1,000,000 plants ha-1. The best colour parameters of beet roots were obtained with green manure amounts of 30 and 32 t ha-1 at an arugula density of 400,000 plants ha-1.

RESUMO Diante da falta de informações sobre o uso de plantas espontâneas do bioma Caatinga como adubos verdes para produção de grãos verdes, esse trabalho teve como objetivo otimizar agronômica e economicamente a produção de feijão-caupi para grãos verdes e de seus componentes quando adubado com quantidades equitativas de biomassa das espécies jitirana (Merremia aegyptia L.) e flor-de-seda (Calotropis procera Ait.) em duas estações de cultivos em ambiente semiárido. O delineamento experimental utilizado foi em blocos completos casualizados, com cinco tratamentos e cinco repetições. Os tratamentos consistiram de quantidades equitativas de biomassa de jitirana (Merremia aegyptia) e de flor-de-seda (Calotropis procera) nas doses de 16, 29, 42, 55 e 68 t ha-1 em base seca. Em cada experimento foi plantado um tratamento adicional com feijão-caupi sem adubo (testemunha absoluta) e outro adubado com fertilizante mineral para efeito de comparação com o tratamento de máxima eficiência fisica ou econômica. As máximas eficiências físicas (agronômicas) otimizadas da produção de vagens e grãos verdes de feijão-caupi foram alcançadas na produtividade de vagens verdes de 3,90 t ha-1 e na produtividade de grãos verdes de 4,06 t ha-1, com a incorporação ao solo de 45,07 e 50,48 t ha-1 de biomassa dos adubos verdes, respectivamente. A máxima eficiência econômica da produção de grãos verdes do feijão-caupi foi alcançada na renda líquida de 5.826,12 R$ ha-1 e na taxa de retorno 1,29 reais por cada real investido com aplicação ao solo de 38,74 e 37,85 t ha-1 de biomassa dos adubos verdes testados.

ABSTRACT Given the lack of information on the use of spontaneous plants from the Caatinga biome as green manure to produce green grains, the present work aimed to agronomically and economically optimize cowpea production for green grains and their components when fertilized with equitable biomass amounts of hairy woodrose (Merremia aegyptia L.) and roostertree (Calotropis procera Ait.) in two cropping seasons in a semi-arid environment. The experiment used a randomized complete block design, with five treatments and five replicates. The treatments consisted of equitable amounts of dry M. aegyptia and C. procera biomass of 16, 29, 42, 55 and 68 t ha-1. In each experiment, an additional treatment was planted with cowpea without fertilizer (absolute control), and another was fertilized with mineral fertilizer for the purpose of comparison with the treatment of maximum physical or economic efficiency. The maximum optimized physical (agronomic) efficiencies of cowpea green pods and grain production were reached in the productivity of green pods at 3.90 t ha-1 and green grains at 4.06 t ha-1, with incorporation into the soil of 45.07 and 50.48 t ha-1 of green manure, respectively. The maximum economic efficiency of cowpea green grain production was reached at a net income of R$5826.12 ha-1 and at a rate of return of 1.29 reals for each real invested with application to the soil of 38.74 and 37.85 t ha-1 of the tested green manure biomass.

ABSTRACT. One of the great challenges of the beet and cowpea cultivation in crop association is to maintain their productivity as that of their sole counterparts in semi-arid environment. In this context, the objective of this work is to assess whether there is bio-agroeconomic return in associations of beet-cowpea by the optimization of population densities and spatial arrangements of the component crops. Experiments were performed in randomised complete block designs with treatments arranged in a 4 × 3 factorial scheme, with four replications. The first factor was the population densities of cowpea (100, 80, 60, and 40% of the recommended population in single crop - RPSC) in association with beet, and the second factor was the spatial arrangements (2:2, 3:3, and 4:4), formed by beet (B) rows alternating with cowpea (C) rows. The competition and agronomic indices evaluated were aggressiveness, competitive ratio, land equivalent ratio, actual yield loss, intercropping advantage and the productive efficiency index. The economic indicators evaluated were gross income, net income, rate of return and profit margin. High agro-economic efficiency can be obtained in the cultivation of beet and cowpea intercropping when well-managing the factors of production, population densities and spatial arrangement of the component crops. The greatest agro-economic return of the cowpea and beet intercropping was obtained in the population densities of 40 and 100% of RPSC for cowpea and beet, respectively. The 2:2 spatial arrangement between beet and cowpea crops was the one with the best productive performance and higher indicators of economic return. The cowpea was the dominant crop while the beet was dominated.

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 de consorciação foram: índice de uso eficiente da terra (UET), razão de área equivalente no tempo (RAET), escore da variável canônica (Z), perda de rendimento real (PRR), vantagem do consórcio (VC), renda bruta (RB), renda líquida (RL), taxa de retorno (TR) e margem de lucro (ML). As maiores vantagens agroeconômicas do consórcio de cenoura e feijão-caupi foram obtidas para UET, RAET, RL e TR de 2,60, 4,16, US$ 8.720,99 ha-1 e US$ 2,21, respectivamente, para as quantidades de biomassa de M. aegyptia de 46,42, 47,82, 32,60 e 31,51 t ha-1, adicionadas ao solo. O arranjo espacial 2: 2 foi o de melhor desempenho produtivo, com maior receita líquida e taxa de retorno no consórcio entre feijão-caupi e cenoura.

ABSTRACT: 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.