BROMIDE TRANSPORT UNDER SPRINKLER AND PONDED IRRIGATION

Chemical irrigation is being used increasingly as a means of applying agricultural chemicals, but the effects of different irrigation practi ces on the movement and distribution of these chemicals in the soil ar e not well understood. This paper reports the results of a field study where bromide is applied as a tracer under both sprinkler and ponded irrigation. The travel-depth bromide concentration curves under sprink ler irrigation were smooth and unimodal, with very little variability between soil cores. For ponded irrigation, however, the curves were bi modal and showed much greater variability between cores. The writers a ttribute the differences in shape and variability to the presence of p referential flow in the ponded case. Results of this study have import ant implications for ground-water pollution potential and monitoring o f the vadose zone,