Agric Horizon - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 76

9.4 Processes Leading to the Formation
of the Agric Horizon

The key process leading to the formation of the agric horizon is compaction from
trafficking of heavy equipment or cultivation of the soil when it is wet.

9.5 Summary

The agric horizon is a compacted layer below the plow zone that is 10 cm thick

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and contains either 5 % lamellae. The agric horizon is not

used currently as a prefix in classifying soils in ST. No soil series with agric
horizons have been identified to date. The key process leading to the formation of
the agric horizon is compaction from trafficking of heavy equipment.

5 % wormholes or

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References

Arvidsson J (2001) Subsoil compaction caused by heavy sugar beet harvesters in southern Sweden.
1. Soil physical properties and crop yield in six experiments. Soil Tillage Res 60:67-78
Assouline S, Tavares-Filho J, Tessier D (1997) Effect of compaction on soil physical and hydraulic
properties: experimental results and modeling. Soil Sci Soc Am J 61:390-398
House ML, Powers WL, Eisenhouwer DE, Marx DB, Fekersillassie D (2001) Spatial analysis of
machine-wheel traffic effects on soil physical properties. Soil Sci Soc Am J 65:1376-1384
Pagliai M, Marsili A, Servadio P, Vignossi N, Pellegrini S (2003) Changes in some physical
properties of a clay soil in central Italy following the passage of rubber tracked and wheeled
tractors of medium power. Soil Tillage Res 73:119-129
Smith CW, Johnston MA, Lorentz S (1997) The effect of soil compaction and soil physical
properties on the mechanical resistance of South African forestry soils. Geoderma 78:93-111
Verbist K, Cornelis WM, Schiettecatte W, Oltenfreiter G, van Miervenne M, Gabriels D (2007)
The influence of a compacted plow sole on saturation excess runoff. Soil Tillage Res
96:292-302