Model studies on upheaval and reconsolidation of tilled soils in a laboratory soil bin

Abstract

Upheaval due to primary tillage operations, generally carried out in autumn, and reconsolidation by gravity and shrinkage and by rain of a silty clay, a sandy loam and a sand soil, tilled with a rotary cultivator, a reciprocating harrow and a subsoiler, with an overall working intensity ranging from 220 to 10 m 2 m −3 and a set working depth of 0.07 m, was studied under laboratory conditions in an indoor, small-scale soil bin. The average upheaval caused by tillage was 45% of the working depth; on the silty clay upheaval seemed to be slightly higher. Reconsolidation was mainly due to disintegration of soil particles by rain and was positively correlated with the upheaval; reconsolidation by gravity and shrinkage played only a minor role. The rate of reconsolidation by rain increased with decreasing clay content and with decreasing working intensity (degree of crumbling) of the implement.