Effects of Combination of Cover Crops and Controlled Agricultural Machinery Traffic on Soybean Performance and Yield

Climate change is one of the current challenges for agricultural production, and sustainable cultivation strategies that mitigate these effects are essential. This study aimed to evaluate the effect of soil cover combined with the intensity of controlled agricultural machinery traffic on soybean development and productivity in two production cycles. The experimental design was a randomized complete block design with a split-plot arrangement with six replications. The main plots consisted of three soil management systems: brachiaria straw, millet straw and spontaneous species straw. The subplots created for agricultural machinery were passed through along the controlled traffic lines (two, four, six, and eight times, and four, eight, twelve, and sixteen times in the first and second years of cultivation, respectively). According to the Köppen classification, the region’s climate is tropical rainy (Aw), with a rainy summer and a dry winter, with an average annual precipitation and temperature of 1520 mm and 24.1 °C, respectively. The traits evaluated were CO2 assimilation rate, stomatal conductance, transpiration rate, internal CO2 concentration, water use efficiency, carboxylation efficiency, stem diameter, plant height, number of branches, number of pods, number of grains, and grain yield. The highest soybean yield was achieved with twice the agricultural traffic, a 22% increase compared to sixteen times the agricultural traffic. With the increase in machinery traffic, the water use efficiency of soybean plants decreased. The stem diameter, number of branches, number of pods, and grains were higher in the spontaneous species straw; however, they did not reflect a higher soybean yield, which was achieved with soil cover with brachiaria and millet, which also promoted greater water use efficiency. It was concluded that the combination of soil cover and agricultural machinery traffic is an effective and sustainable strategy for promoting a higher soybean yield.