Percolation of Surface‐applied Water in the Field

Abstract

AbstractPercolation of surface‐applied water tagged with chloride was studied in Maury silt loam and Huntington silty clay loam under field conditions. Soil samples were taken in small increments to the 90‐cm depth several times following application of water. Analyses of chloride content with depth indicated the position of the applied water relative to the initial soil water in the profile.Three percolation studies were conducted on Maury silt loam soil. In study 1 an application of 4.2 cm of water increased the water content to the 60‐cm depth within 1 hour following irrigation even though the volumetric water profile averaged 5% below the upper limit of the water holding capacity through this depth. A second study conducted at a slightly higher initial water content showed that 20% of a 4.2‐cm application had penetrated below the 90‐cm depth immediately after application and 40% penetrated below this depth within 1 hour.Similar results were measured in Huntington silty clay loam. Simulated rainfall increased the water content significantly to approximately the 15 cm depth in each of three studies. A large percentage of the water passing this depth apparently percolated past the 90‐cm depth with very little adsorption of water and chloride between these depths.Location of chloride in the profile and movement of chloride past the 90‐cm depth indicated that a large percentage of the applied water percolated past the water initially present with little displacement of the initial water.