Influence of Soil pH ons-Triazine Availability to Plants

Abstract

Field studies indicated that liming an acid Bladen silt loam from pH 5.5 to 7.5 increased the phytotoxicity of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and prometryn [2,4-bis-(isopropylamino)-6-methyoxy-s-triazine]. Liming greatly increased the persistence of atrazine, but did not affect prometryn dissipation. Liming increased the14C-concentration present in the shoots of corn (Zea MaysL. ‘Pioneer 3369A’), cotton (Gossypium hirsutumL. ‘Coker 201’), and soybeans [Glycine Max(L.) Merr. ‘Ransom’] from soil treated with14C-ring labeled atrazine, prometryn, and hydroxyatrazine [2-hydroxy-4-(ethylamino)-6-(isopropylamino)-s-triazine] in greenhouse studies. Decreases in14C-uptake by the crops were associated with adsorption and degradation of the compounds in the soil. Atrazine was taken up in much greater amounts than hydroxyatrazine. Cotton absorbed less of thes-triazines than soybeans or corn from soil.