The effect of lateral movement of water in soil on infiltration measurements

Abstract

The effect of lateral movement on minimum infiltration capacity was examined using small flooded plots of various sizes without buffer zones and using small sprayed and flooded plots surrounded by wetted buffer zones. When no buffer zones were used, the minimum infiltration capacity of a given soil decreased with increasing size of plot and there was a corresponding increase in the fraction of applied water remaining beneath the plot at the conclusion of the trial. An expression for the relation between plot size and lateral movement is discussed. Although buffer zones around flooded plots effected some reduction in lateral movement, the measurements were subject to considerable error and the method was considered unduly cumbersome for routine work. In a spray infiltrometer procedure, a sprayed buffer zone surrounding a small test plot was found to be effective on the soils examined. When all data from flooded plots with and without buffer zones were examined, it was found that the minimum infiltration capacity of a soil varied inversely with the fraction of applied water remaining beneath the plot a t the conclusion of a trial. When the minimum infiltration capacity was multiplied by the corresponding value of this fraction, the effect of lateral movement was reduced considerably. It is shown that results from small plots then approximate more closely to those to be expected from large ones and there is also a reduction in variability due to causes other than variation in size of plot. Limitations in the use of this correction factor are discussed fully and the general limitations of infiltration data derived from small plots are briefly considered.