The cause of the formation of acidic subsurface layers in urine patches was examined.The rate and magnitude of N processes occurring under simulated urine patches in column studies in the glasshouse and laboratory were examined in 2 cm depth increments and related to the observed changes in soil pH. A H+ balance model was used to determine the magnitude of the soil pH change attributed to the N processes of urea hydrolysis, NH3 volatilisation, nitrification, and net mineralisation/ immobilisation in a soil column study in the absence of plants. The influence of plant growth on soil pH change after application of simulated urine was investigated in a soil column system. The effect of varying concentrations of simulated urine constituents (urea-N and KCl) on soil pH after application to soil under actively growing plants was also determined. A field study was conducted to substantiate the formation of acidic subsurface layers in a ryegrass pasture during two varying environmental seasons. Acidic subsurface layers were produced in both spring and summer as a result of N transformations occurring after the application of simulated urine solutions.
|Qualification||Doctor of Philosophy|
|Award date||01 Mar 2002|
|Place of Publication||Australia|
|Publication status||Published - 2002|