Produtividade, conteúdo de óleo e retorno econômico financeiro de cultivares de soja irrigada

Abstract

The objective of the present study was to investigate the technical and economic-financial viability of the production of soybean cultivars, under different water supplements for the production of soybean oil. Two experiments were carried out in the 2017/18 and 2018/19 agricultural years, in an experimental area belonging to the Polytechnic College of UFSM, in Santa Maria, RS. The experimental design was in a two-factor scheme, where the first factor was five irrigation depths plus the non-irrigated control (0, 25, 50, 75, 100 and 125% of the reference evapotranspiration, ETO) and the second factor was three soybean cultivars. (NIDERA 6909, BRASMAX Ponta and BRASMAX Valente). Grain yield, grain oil content, water yield and economic yield of water for grain production and oil content were evaluated. The economic-financial return was evaluated by the net present value, the internal rate of return, the benefit/cost ratio and the payback, in 72 scenarios, for four crude oil commercialization prices. The maximum technical efficiency for grain yield was obtained for depths of 73.03% (crop 1) and 77.94% of ETO (crop 2). There was a statistical difference for grain yield between the cultivars, and in both seasons, BRASMAX Valente presented the highest average values. In both seasons, water productivity and economic water productivity for grain production were higher for 50% and 25% of ETO, respectively. For the oil content, the maximum technical efficiency was obtained in the depths of 100.5% (crop 1) and 98.17% of ETO (crop 2) and the cultivar BRASMAX Ponta presented the highest results. The water productivity and the economic water productivity for grain and oil production presented higher average values with the use of a 50% ETO depth. BRASMAX Valente (crop 1) and BRASMAX Ponta (crop 2) obtained the highest results in water productivity and economic water productivity in oil production. The oil commercialization price at R$ 2.50 .kg-1 was not economically viable, in the different irrigation depths and cultivars. At the prices of R$ 6.50 and R$ 8.50 .kg-1, the economic return was satisfactory for all the conditions tested. Supplementary irrigation favored the increase in grain yield, oil production and oil yield. Economic water productivity is maximized by reducing the irrigation depth.