Equipments to manage soil and irrigated rice straw for the sequential sowing of soybean in tropical floodplains

The presence of straw hinders the sowing of soybean cultivated in succession to rice, in areas irrigated by flooding. This study aimed to evaluate the combination of different configurations of a rice harvester and subsequent activities in the operational and energetic demand of rice straw management and in the soil surface roughness, in order to cultivate soybean in succession. Three independent experiments were conducted in a completely randomized design, as well as evaluated the fuel consumption, effective operating speed, working capacity and final surface roughness of the ground. The energy costs of harvesting rice do not increase when the automated harvester operates with a spreader to distribute the straw on the ground and to avoid the formation of furrows. The presence of rice plant residues in the field increases the skidding of the tractor when pulling the knife-roller, with a consequent reduction of the operating speed, but this does not affect the operational capacity and the fuel consumption. The increase in the number of light harrowings, from one to two operations, in areas worked with knife-roller or intermediate harrow, requires more time and fuel in the management of the soil and rice straw, but leaves the ground with less surface roughness. The management system with knife-roller operation and two light harrowings is the most appropriate method to prepare the soil for soybean cultivation after rice, because it provides the best combination of technical and energetic performance.