Compactação do solo e produção de massa seca de sorgo

Abstract

Sorghum (Sorghum bicolor L.) is a plant with high photosynthetic rates and can be cultivated in almost all national territory. This crop is very useful in very hot and very dry regions, where crops such as corn do not reach the maximum in grain or forage yield (Molina et al., 2000). The term soil compaction refers to the compression of the unsaturated soil during which there is an increase in its soil density (Ds) as a result of the reduction of its volume (Gupta et al., 1989). The experiment was conducted in the experimental area of the Federal University of Pampa, Campus Itaqui-RS, in the 2015/16 crop. The experimental design was randomized blocks with four treatments, four replications, plots of 12 m² (3 x 4 m). The four treatments were: a) zero tractor zero; b) one tractor pass; c) two tractor passes after soil preparation, d) control, without tillage and without machine traffic; For the physical analyzes, 4 x 3 subdivided plots were used, three of which were the soil layers (0-5, 5-10 and 15-20 cm). Ds occurred reduction of macroporosity. This results in lower soil physical quality, since it already has a number less than 10% macroporosity, which is the minimum necessary for crop development (Reinert & Reichert, 2006). There is no described percentage for sorghum crop, so the reduction of 7 to 4% of the macroporosity, in the treatment of zero past tractor for the treatment with two passes of tractor, reduces the gaseous exchanges and circulation of water in the soil, with reflections on productivity. When there is no machine traffic, the dry mass yield of sorghum is 12.2 t ha-¹.