AMMONIA VOLATILIZATION FROM UREA AMENDED WITH LIGNOSULFONATE AND PHOSPHOROAMIDE

Concern about losses Of fertilizer N and pollution of the environment has stimulated research to find compounds that will reduce these problems by effectively inhibiting urease activity and nitrification. Laboratory studies were carried out to evaluate the effects of ammonium lignosulfonate (LS), thiophosphoric triamide (NBPT), and phenylphosphorodiamide (PPD) on NH, loss from urea fertilizer. We examined NH, losses from surface-applied urea and from banded urea (2 cm below the soil surface) in samples of Ste. Rosalie clay soil (fine, mixed, nonacid, mesic Typic Humaquept) exposed to an initial water pressure of - 0.01 MPa. Formulations of solution, physical dry blend, and tablets were used. Measurements of NH, volatilization were carried out using an air train system. Ammonia loss from surface-applied unamended urea ranged from 16 to 21% of urea-N applied. Amending urea with LS induced between 46 and 85% reduction in NH, losses compared with the unamended urea. For tablet and physical dry blend formulations, banding reduced NH, loss compared with the surface application. There were no significant differences in NH, losses between surface-applied and banded treatments of solid fertilizer. Comparison of the effects of LS, NBPT, and PPD on NH3 volatilization showed that both NBPT and PPD were more effective in reducing NH, loss than LS, but no significant differences between NBPT and PPD were found.