Dye tracers aid rice chemical residue studies

Small-scale rectangular plots at Davis are being used to determine how long chemicals applied in rice fields persist in flood and seepage waters, where the chemical residues go, and how fast they get there. This article presents data from some dye tracer experiments using two chemical application techniques (uniform application on the water surface and slug injection at the point of water inflow) and three water management practices (static, flow-through, and recycled systems). The distribution, persistence, and movement of a rhodamine dye tracer in flood waters was found to be greatly affected by these different water management systems.