Transferability of Lysimeter Results to Actual Field Situations

Transferability of lysimeter data to the field was investigated using the leaching and degradation behavior of14C-labeled metamitron [4-amino-3-methyl-6-phenyl-2,4-triazin-5(4H)-one] and methabenzthiazuron [1,3-dimethyl-3-(2-benzthiazolyl)-urea]. Forty-one to 53 days after application about 4% of the applied metamitron was detected in the upper 20 cm of the field soil either as active ingredient or the major metabolite desamino metamitron, whereas about 8% was found in the lysimeter soil. Forty percent and 33% of the applied methabenzthiazuron were identified in the 0- to 10-cm soil layer in the field and lysimeter 127 to 133 days after application, respectively. It is demonstrated that lysimeter experiments using14C-labeled compounds simulate actual field conditions and give further information about the amount of total14C-residues in the soil and percolate.