Produtividade e rentabilidade da forragem de sorgo sob lâminas de irrigação e níveis de cobertura morta em condições semiáridas

Abstract

The sorghum (Sorghum bicolor L.) crop has a wide use in the production of fodder, being harvested in the form of hay and silage and grazing. It is highly cultivated in arid and semi-arid regions, however, often with low yields in rainfed conditions, despite its high climatic adaptability. Therefore, the low regional water availability raises techniques to mitigate the effects of water stress, such as the use of mulch. The objective of this study was to evaluate the production and profitability indicators of forage sorghum (BRS Ponta Negra) under different irrigation levels (50, 75, 100, 125 and 150% of crop evapotranspiration, ETC) carnauba bagana (0.00, 2.50, 3.75, 5.00 and 6.25cm). The study was conducted in the Federal Institute of Education, Science and Technology - Umirim Campus, from September 2016 to January 2017. The experimental design was arranged in subdivided plots, 5 x 5, with 5 replications, totaling 125 experimental units . The analyzed variables were: plant height, stem and panicle diameters and panicle length; forage and dry mass production and water use efficiency; and indicators, beneficial relation / cost, net present value, internal rate of return and payback period. The morphological variables were significantly influenced by the applied slides, with increasing linear increase for the variables plant height and panicle length. The stem and panicle diameters showed maximum values with slides close to 100% ETc; Water and bagana levels significantly influenced the forage yield of sorghum, which increased with the increase of these factors. The adoption of deficit irrigation reduced forage production, however, increased the efficiency of water use; Sorghum production proved to be financially viable for all indicators under review, for all applied irrigation slides and for all levels of mulch, indicating that this crop is a promising crop for the region. However, the use of the highest applied blade, equivalent to 150% of the ETc and the non-use of mulching, proved to be the most economically feasible conditions for the sensitivity analysis of costs and revenues; As a strategy for the growth of the exploitation of this crop, it is necessary to valorize the policies of access to credits, such as Pronaf, as well as the association of techniques of conservation management mainly of soil and water.