Correlation of the least limiting water range with soil physical attributes, nutrient levels and soybean yield.

Abstract

In soils that are compacted or undergoing compaction, the interval of water available to the plants can decline to zero, which according to the least limiting water range (LLWR) method is called the critical soil bulk density (Bdcritical), when LLWR = 0. The aim of this study was to determine the LLWR of a highly clayey typic dystrophic Red Latosol (Oxisol) and to correlate it with the soil physical attributes, nutrient levels and soybean yield, because hypothetically if there is a negative correlation, the use of the LLWR associated with spatial variability maps can help reach decisions regarding intervention or modification of soil management. We observed that in no-till farming, limitation of plant development can occur as the soil dries out, mainly due to the higher resistance to mechanical penetration. Besides this, we found that the LLWR0- 0.10m and LLWR0.10- 0.20m values were correlated in greater numbers with macronutrients and micronutrients analyzed, and also with the land slope, compared the correlation with the soybean yield data. Therefore, nutritional analysis of the grains complemented by physical analysis of the soil can be used to identify nutritional imbalances that are not otherwise observable and thus, the LLWR can be useful for planning corrective actions regarding soil and crop management, based on measurement of the Bdcritical. Key words: No-tillage system, no-till farming system, soil physical quality indicator, spatial variability of soil water content.