Soil compaction influences soil physical quality and soybean yield under long-term no-tillage

摘要

Soil compaction under no-tillage (NT) exerts a negative impact on the soil physical quality. The objective of this study was to quantify the influence of compaction on soil's physical quality and soybean crop yield in a Rhodic Ferralsol under NT in southern Brazil. Soil compaction was established through an increasing number of passes (0, 3, 6, and 9 passes) by a 4510 kg tractor, which promoted a degree of compactness of 84, 89, 94, and 99, respectively. Undisturbed soil samples were taken from depths of 0.0-0.1 and 0.1-0.2 m from row (R) and interrow (IR) after soybean harvests in 2014 and 2015 seasons. Soil bulk density (Bd) and least limiting water range (LLWR) were then determined. Also, soybean yields were evaluated. The contrast in Bd and LLWR observed between R and IR positions was restricted to the 0.0-0.1 m soil depth layer. The assessment of LLWR under NT must consider the sampling positions. The increase in the degree of compactness promoted soil physical quality degradation and decreasing soybean yield (up to 12 and 19 for 2013 and 2014 seasons, respectively). The LLWR has been correlated to soybean yield and could be a useful tool for soil management practices.