Test No. 502: Metabolism in Rotational Crops

Metabolism in rotational crops studies are conducted to determine the nature and amount of pesticide residue uptake in rotational crops that are used as human food or as livestock feed.

The provide an estimate of total radioactive residues in the various raw agricultural commodities (RACs); identify the major components of the terminal residue in the various RACs; elucidate the degradation pathway of the active ingredient in rotated crops; provide data to determine appropriate rotational intervals and/or rotational crop restrictions based on residue uptake levels; provide information for determining if limited field trials for rotational crops should be performed. The active ingredient should be labelled, to allow for quantification; the preferred radioisotope is 14C, although 32P, 35S can be used. The study should be performed using a sandy loam soil treated with the radiolabelled test substance. The study may be performed either in a greenhouse or in an outdoor plot or container or a combination of the two. Three appropriate rotational intervals should be used (7-30 days for rotated crops, 60-270 days to reflect a typical rotation after harvest of the primary crop and 270-365 days for crops rotated the following year). Three Rotational crops should be used and be representative of each of the following crop groupings: root and tuber vegetable; small grain; and leafy vegetable.

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