Seeding density of Brachiaria ruziziensis intercropped with grain sorghum and effects on soybean in succession

Sorghum is an alternative crop to produce grains in the off-season in Brazilian Cerrado and the intercropping with Brachiaria species enable to produce dry matter on the soil surface for a longer time. However, there is limited information on Brachiaria ruziziensis seed density to be applied to intercropping with sorghum without causing decreases in sorghum grain yield. The objective of the study was to evaluate the seeding density of B. ruziziensis in different intercropped systems with grain sorghum grown after soybean harvest, in off-season cultivation, to produce grains and the effects of straw on the agronomic performance of the soybean crop in succession to intercropping. This study was conducted in the field during the 2014 off-season in Rio Verde, Goiás. The experimental design was complete randomized blocks in a 3×5 factorial arranged with four replications corresponded to intercropping on rows, inter-rows and broadcast sowing with the densities of 2, 4, 6, 8 and 10 viable pure seeds m-2 of B. ruziziensis. Monocultures of sorghum and these forage crop were also evaluated. The results demonstrated the absence of effects of intercropping systems and seeding density on the yield of sorghum grains and on the cultivation of soybean in succession. The intercropping was effective in producing straw on soil surface to Cerrado no-tillage system. Key words: Brachiaria species, Glycine max, straw, off-season crop, Sorghum bicolor.