Wetting patterns and associated Pdistribution under drip emitters in two Oxisols

Laboratory studies of two-dimensional water movement and P-distribution from line source water application were conducted using clay and sandy loam Oxisols. Horizontal advance of the wetting-front approached a limit in distance with prolonged application time in both soils. A linear relationship between the vertical advance and the square root of time was observed. Increasing application rates resulted in more lateral water movement and shallower downward movement. Phosphorus was found as far as 30 cm from the application point in the sandy soil profile, but no significant movement of phosphorus was observed in the clay. Simple equations are suggested to aid in the design and operation of drip systems on Oxisols. Supplementary P-application and/or organic phosphorus fertilizer are recommended for use with drip irrigation.