Soil surface roughness as influenced by selected soil physical properties

Abstract

Soil surface roughness affects infiltration, the storage of water in depressions on the soil surface, runoff and other processess. Roughness of soil after tillage or cultivation is affected by soil factors such as soil type, soil aggregation, water content and others. Specific soil properties that determine a soil's physical reaction to tillage should be identified, so that mechanistic relationships between those properties and the resultant roughness can be developed. The objective of this study was to determine relationships between soil surface roughness, measured using an MIF parameter (the product of a microrelief index and peak frequency), and water content, bulk density, soil texture, wet and dry aggregate size distributions, aggregate stability, organic matter content and other soil properties, measured after each of3 cultivations throughout a growing season. During the summer of 1984, soil physical properties at depths of 10.8 and 30.5 cm were measured prior to primary tillage, and at the surface immediately before 3 cultivations of soya beans, Glycine max (L.) Merr. An automated, non-contact profiler measured surface profiles along transects, 5 cm apart, of 1 × 1 m plots after each cultivation. With water content and dry bulk density at the soil surface ranging from 0.06 to 0.21 kg kg −1 and from 1.05 to 1.26 Mg m −3, respectively, roughness, as the common logarithm of MIF, ranged from −0.758 to −0.788. Dry and wet bulk density were found to account for 64 and 52% of the variation in the MIF parameter, respectively. Water content at cultivation, and at −33 kPa, accounted for 21 and 22%, respectively, of the variation in surface roughness.