Field Evaluation of Water and Solute Distribution from a Point Source

Abstract

Field measurements of water and solute distribution from a point source were made using the gravimetric method. The variables affecting water and solute distribution, including application rate (1.5, 2.0, and 2.5 L/h), applied volume (15, 20, and 25 L), and input concentration (100, 300, 500 mg/L) were studied and their effects are presented. There was an increased soil water content both with a higher application rate and applied volume up to about 25 cm depth and 30 cm radial distance, beyond which the difference was not significant. There was a clear relationship between application rate and shape of the wetted soil zone. An increase in rate resulted in an increase in the wetted horizontal area and decrease in the wetted soil depth for the same application volume. Solute concentration increased with higher input concentration, applied volume, and application rate up to about the same depth and radial distance as for soil water content. The wetted and chemigated soil volume was larger for higher volumes applied. This information is useful in the design, operation, and management of a chemigation system with microirrigation.