|MULLER, LOTHAR - Leibniz Centre|
|LIPIEC, JERZY - Agricultural University Of Poland|
|GEBHARDT, STEPHAN - University Of Kiel|
Submitted to: Encyclopedia of Agrophysics
Publication Type: Book / Chapter
Publication Acceptance Date: 5/6/2010
Publication Date: 7/4/2011
Citation: Muller, L., Lipiec, J., Kornecki, T.S., Gebhardt, S. 2011. Trafficability and workability of soils. Encyclopedia of Agrophysics. P. 912-924.
Interpretive Summary: In agriculture, soil management for plant production can be influenced by the use of efficient machinery. Many operations like tillage, fertilization or harvesting require the use of tractors or other self–propelled and/or load bearing machinery. Trafficability is the capability of land to provide field traffic operations without degradation to agroecosystems, forests and grasslands. Degradation includes all detrimental effects to soil structure, fertility and vegetation. In agroecosystems, trafficability should be a precondition for soil tillage and is thus related to workability. Trafficability can be assessed by different parameters, characterizing shear strength, moisture and density of soil. Weather conditions and shallow water tables and drainage significantly influence trafficability. Based on available knowledge of field trafficking processes, evolving operational trafficability forecasting models seems to be feasible. Model combinations should include deterministic, probabilistic and auto-regressive statistical approaches. Workability is the capability of soil to be tilled, and it is largely dependent on soil moisture. Defining appropriate moisture criteria and calculating suitable field moisture may be important for planning tillage operations. Parameters used for indicating potential soil wetness in relation to workability may be derived from the field water capacity, soil water potentials, and inflection point of the water retention curve. In humid areas, soil moisture deficits for springtime tillage are critical and allow for only shallow operations. In sub-humid and semi-arid regions, restrictions of workability due to dry and hard soil conditions have to be considered. Besides existing recommendations for avoiding accelerated soil compaction, new measures should be taken into account. These include restricting loads of machinery by environmental impact assessment procedures for heavy vehicles and evolving operational forecasting of trafficability.
Technical Abstract: Trafficability and workability are soil capabilities supporting operations of agricultural machinery. Trafficability is a soil's capability to support agricultural traffic without degrading soils and ecosystems. Workability is a soil capability supporting tillage. Agriculture is associated with mechanical impacts on soils to provide optimum conditions for all processes relevant to plant production. Processes like tillage, seeding, fertilization or harvesting are highly mechanized and require agricultural traffic. Soils have to support those operations, but the soil conditions may include periods that are unsuitable for agricultural traffic and tillage. Agriculture is climate and weather-dependent. Due to basic soil properties, climatic and weather conditions and land use and management, the status of soils varies both temporally and spatially. Main limitations both of the mobility function of tractors and the risk of soil compaction are due to excessive soil water content. The term trafficability refers largely to soil moisture conditions providing or restricting field traffic by machinery. Trafficability is a significant factor in carrying out farm field operations, especially after rainfall events when poor trafficability can cause delays in planting, cultivating, harvesting, and transporting of field crops. But also in forests and on grassland, trafficability of soils is a necessary operation. Workability refers to soil tillage and is most relevant to agro-ecosystems. In cropping agriculture, soil structure of the main rooting zone can be influenced by primary tillage like ploughing or cultivating. Operational parameters depend on soil status, specific requirements of crops and the kind of general tillage purpose to be produced by special tillage implements. The desired result will only be achieved if the soil has an appropriate workability.