Investigation of the behaviour of pesticides in soil environment by using isotope tracer techniques. Part of a coordinated programme on isotope-tracer-aided studies of agrochemical residue - soil biota interactions

Studies were conducted to characterize the behaviour of 14C-carboxyl-labelled 2,4-D (2,4-dichlorophenoxy acetic acid) in soil-plant systems under laboratory, greenhouse and field conditions. Results indicated that degradation, of the chemical was faster in soil rich in organic matter and that moisture content did not affect degradation rates significantly. Under greenhouse conditions, barley, wheat and oat plants took up less than 1% of the amount of herbicide applied to soil. Under field conditions, 15% of the applied 14C-activity was recovered in soil-methanol extracts prepared by Soxhlet extractor for 48 hours. Soil radioactivity, remaining after extraction, was determined by a wet combustion procedure and was found to account for 48% of the applied herbicide after four weeks. The balance of 37% was presumably lost as 14C-carbon dioxide