Tillage in relation to rainfall intensity and infiltration capacity of soils.

Abstract

Starting from Darcy's law, the rate of infiltration of water into homogeneous and layered soils is given. At field capacity the rate of infiltration approaches that of percolation. The influence of an upper layer of high permeability on infiltration rate of the subsoil is small; loosening the surface layer increases infiltration capacity until it is saturated and further infiltration is limited by the percolation rate of the subsoil at field capacity. Stagnation of water at the soil surface during periods of high rainfall intensity may be prevented by cultivation. A graph shows maximum rainfall surplus to be dependent on percolation rate. Cultivating soil in view of infiltration capacity is not important if the percolation rate of the subsoil is >1.5 cm/hr, since corresponding high rainfall intensities occur in summer when soil is not bare and potential evapo-transpiration is high. With low percolation rate and a potential storage capacity of the upper layer X'p = 0.25, a depth of 11-22 cm of the upper layer is sufficient to store the maximum surplus rain in Holland even during extreme wet periods. The total storage capacity of subsoil is only limiting with small depths or very low values of potential storage capacity. (Abstract retrieved from CAB Abstracts by CABI’s permission)