A case study on the effect of soil compaction on potato growth in a loamy sand soil. 1. Physical measurements and rooting patterns.

Abstract

An interdisciplinary field study, including consideration of soil tillage, soil physics, pedology and crop science was made to study the effect of soil compaction on potato growth in a young alluvial loamy sand soil in the very dry growing season of 1976. The treatments consisted of different degrees of compaction in or just below the arable layer and also consider the effect of irrigation. Compaction decreased soil pore vol. whereas the volumetric water content at any given pressure potential was increased or decreased depending on the degree of compaction. A high mechanical resistance encountered by the roots proved to be the primary factor affecting root elongation. Roots penetrated the compacted layers in all treatments but at very different rates. As a result the pressure potential at the rooting front was relatively low as long as roots were growing in the compacted layers. Moisture flow to the roots by capillary rise from the water table occurred during the entire growing season but varied significantly among treatments as a function of the distance above the water table and hydraulic conductivity of the various layers. Moderate compaction increased, but severe compaction decreased, the potential for capillary rise in the topsoil. The plough pan in the subsoil increased the potential for capillary rise. Critical groundwater levels at a given rooting depth were calculated for different steady upward fluxes for some of the treatments. (Abstract retrieved from CAB Abstracts by CABI’s permission)