Soil moisture and workability of heavy arable soils

Abstract

The objective of this study was (i) to quantify the workability of soils as a function of the soil moisture status, and (ii) to derive moisture related threshold values of workability for modelling purposes. On two sites with clay contents of 18% (sandy clay loam) and 53% (clay) located in a Holocene landscape near Berlin, soil moisture parameters were measured and the actual workability of the soils was evaluated. These data were used to derive soil moisture threshold values of workability for different tillage operations and working depths. Results showed that the stickiness of the soils, particularly of the soil surface, was the limiting factor for workability. Loose topsoils began to stick at about the lower plastic limit which occured at about 20% soil moisture at the sandy clay loam and 28% at the clay site. The derived soil moisture threshold values of workability were found to be close to the lower plastic limit. Hand‐hoeing and digging by spade were considered to be less sensitive to the soil moisture status.