Nutrient Transformations in Soils Under Aerobic and Anaerobic Conditions

Poultry litter is most commonly land applied as a fertilizer for pastures. Soils vary according to landscape position and the biogeochemistry changes within the soils depending on the landscape position. This research focuses on nutrient speciation in aerobic and anaerobic environments. A 3.4 kg Ha-1 chicken litter application rate was used to determine the speciation of nutrients in these two environments. A 50 g sample of Ruston soil was placed in 250 mL centrifuge tubes and continuously stirred in anaerobic and aerobic environments. The Eh and pH were measured daily and a sample was collected at 0, 3, 7, 14 and 21 days. The Eh decreased from around 600 mV at day 0 to near 100 at day 2; whereas the aerobic sample had a decrease to around 450 mV. The pH increased from 6.5 to 7.0 in the anaerobic soil and from 6.5 to around 8.0 in the aerobic soil. The anaerobic soils had a rapid decrease in NO3- and a sharp increase in NH4+ to around 100 mg NH4+ kg-1 soil at day 7. The aerobic soil had an increase in NH4+ to 70 mg Nh4+ kg-1 soil at day 7 then decrease in NH4+ with a corresponding increase in NO3-. Both the anaerobic and aerobic soil had a rapid decrease in PO42- concentrations and remained low for 21 d.