|Mueller, Lothar - CEN FOR AG. LAND AND LAND|
|Schindler, Uwe - CEN FOR AG. LAND AND LAND|
|Lal, Rattan - OHIO STATE UNIVERSITY|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 2003
Publication Date: February 28, 2003
Citation: MUELLER, L., SCHINDLER, U., FAUSEY, N.R., LAL, R. COMPARISON OF METHODS FOR ESTIMATING MAXIMUM SOIL WATER CONTENT FOR OPTIMUM WORKABILITY. SOIL & TILLAGE RESEARCH. 2003. V. 72. P. 9-20. Interpretive Summary: Farmers are beginning to use more technology to help make decisions about farming. For activities that involve the interaction between the farming machines (tools) and the soil, it is desirable for the farmer to know whether or not the soil is workable before attempting these activities. This report tells about a way to predict the workability of the soil based on certain properties of the soil, and it defines the optimum water content for soil workability.. The result was developed using soils from the U.S. and Germany. With this technology, field sensors will be able to signal the readiness of the soil for being worked.
Technical Abstract: The objective of this study was to estimate and evaluate the optimum soil water content for workability of some typical soils in different regions. Parameters and data of water retention curves were compared with soil engineering properties data such as Atterberg limits and Proctor compaction tests. The database includes 70 topsoils, 37 from Germany and 33 from the North Central Region fo the U.S.A. Additionally, on three sites in Germany, the soil water content in the field was studied more intensively and related to workability estimates. The results show that suitable moisture contents for tillage are somewhat lower than the lower plastic limit, as a consistency index of 1.15 or about at 0.9 LPL. These suitable conditions are outside of the plastic range of cohesive soils. In terms of parameters valid for all soils, the optimum water content for workability is at the moisture content at maximum Proctor density or about at 70% of the water content at pF 1.7. At the water content of the inflection point of the water retention curve, in most cases the soil is too wet for tillage. Texture dependent tuning factors for estimating the optimum water content for workability from the inflection point of the water retention curve rage from 0.7 to 1. To estimate optimum workability water content from the maximum water content of the Proctor curve, tuning factors range from 0.9 to 1.2.