Resposta da irrigação na produção de forragem de milheto

Abstract

Irrigation is a technique that seeks to ensure high yields and reduce periods of forage scarcity. With the inclusion of irrigation, there is an increase in the cost of production, this should be less than the income added to ensure sustainability in their use. The objective of this study was to evaluate the technical and economic performance of irrigated millet forage production. The study was developed in the agricultural crops of 2014/2015, in Santiago, RS and 2015/2016, in Santa Maria, RS. The experimental design was organized in randomized blocks with four replicates and six levels of supplementary irrigation: 0, 25, 50, 75, 100 and 125 % of the reference evapotranspiration (ETo). The ETo was determined by the Penman-Monteith method (ALLEN et al., 1998). The millet crop (cultivar ADR500) was sown in the months of November 2014 and 2015, under no-tillage system, with spacing of 0.36 m between rows. The dry matter yield of forage was evaluated, being the collections at 50, 80, 110 and 140 days after sowing (DAS) at a height of 0.15 m in relation to the soil surface. With the conversion of forage yields of millet to animal live weight and the quantification of forage production costs, the benefit-cost ratios of the non-irrigated and irrigated production of five agricultural crops were compared (2012/2013, 2013/2014, 2014/2015, 2015/2016 and 2016/2017) for the two regions. Significant effect was observed for the production of millet fodder in the two agricultural seasons 2014/2015 and 2015/2016, adjusting to the quadratic equation. The maximum technical efficiencies among the treatments were found for the two crops on the 125 % ETo level, with forage yields of 15,494.47 and 14,779.50 kg DM ha-1, respectively. The water productivity did not present statistical difference for the different treatments, with averages of 1.86 and 1.69 kg of DM m-3, respectively. It was verified that the inclusion of irrigation in the forage productive system increased the total cost of production, on average, by 13.42 %. Fixed conventional sprinkler irrigation is economically viable, increasing the economic return, for the conditions of this study.