Release of Soil-Bound Prometryne Residues Under Different Soil pH and Nitrogen Fertilizer Regimes

Abstract

The release of soil-bound14C-prometryne [N,N′-bis(l-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] residues was affected by soil pH, fertilizer treatments (with or without plants), and the crop species wheat [Triticum aestivum(L.) Merr. ‘Marquis’] and soybean [Glycine max(L.) Merr. ‘Maple Presto’]. More of the bound radioactivity was released following large pH changes in the soil than with small deviations. In addition, more14C-prometryne was found in the extracts of the soil incubated with large pH alterations. Fertilizing with ionic nitrogen sources (NO3–and NH4+) in the absence of plants was also responsible for releasing higher levels of radioactivity than with the nonionic fertilizer urea. These fertilizer-induced differences in release were not apparent when wheat plants were added to the system. Release of the bound radioactivity, however, was plant specific, particularly in the rhizoplane, since soybean roots elicited a greater release in the rhizoplane than wheat roots. Transport and metabolism of these residues were also plant specific.