AMMONIA FERTILIZER INFLUENCES ATRAZINE ADSORPTION-DESORPTION CHARACTERISTICS

摘要

The application of ammonia-based fertilizer (anhydrous ammonia, aqua ammonia, and urea) initially increases soil pH. Changes in soil pH influence dissolved organic carbon (DOC) concentrations in soil solution and herbicide sorption characteristics to soil. A batch study was conducted to evaluate the influence of ammonia application on atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-1,3,5-triazine] adsorption and triazine] adsorption and desorption characteristics to a Brandt silty clay loam (fine silty, Pachic Udic Haploborolls) and Ves clay loam (fine silty, mixed mesic typic Hapludalf). Ammonia treatment rates were equivalent to N concentrations found in bands when 0, 100, and 200 kg of N ha(-1) were injected to soil. Atrazine treatments were 0 (0.01 M CaCl2), 2.08, 6.57, or 50.80 mu mol of atrazine L(-1). The application of 200 kg of N ha(-1) increased soil pH from 6 to 9 and increased the DOC concentrations from 60 to 700 ppm in the soil solution. The addition of ammonia decreased atrazine sorption by 50% and doubled atrazine desorption. Ammonia-induced changes in both pH and DOC concentration appeared to influence atrazine sorption characteristics. Ammonia-induced changes in atrazine sorption/desorption characteristics have the potential to increase atrazine movement through soil. These results suggest that atrazine movement may be reduced by physically separating the application of atrazine and ammonia-banded fertilizers.