Equipments to manage soil and irrigated rice straw for the sequential sowing of soybean in tropical floodplains1

Abstract

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.

Management of rice straw in rice-soybean succession in tropical lowland

“…This management method employs a smaller number of machinery operations than the managements M7 and M8. These results corroborate those of Theisen et al (2018) and Silva et al (2019).…”

“…The increment in rice yield increases the production of straw and may hinder tillage operations and the sowing of soybean within the recommended period (Silva et al, 2019). Traditionally in Tocantins lowlands, rice straw is burned.…”

“…An alternative to burning would be the use of disc harrow and leveling disc harrow, which can incorporate the rice straw while also correcting the soil surface roughness. However, the increment in rice yield increases the production of straw and may hinder tillage operations and the sowing of soybean within the recommended period (Silva et al, 2019). Knoblauch et al (2014) report that the incorporation of rice straw in the soil should be carried out at least 30 days before sowing another crop in succession.…”

“…Therefore, it is necessary to assess whether using the knife-roller facilitates the soil tillage for the implementation of the soybean crop in Tocantins lowlands and preserves the possible benefits of rice straw incorporation, with less negative impact on the soil quality. Moreover, if the kniferoller method leads to the same agronomic results as burning and disc harrow-based tillage, the efûciency of the overall cropping system is increased, since the kniferoller demands less energy for soil preparation, reduces greenhouse gas emissions, and allows an earlier soil preparation for soybean crop than the traditional rice straw management used in the Tocantins lowlands (Theisen et al, 2018;Silva et al, 2019).…”