Comparison of type and depth of lysimeter for measuring the leaching losses of nitrogen under urine patches

A study of the leaching losses of nitrate under urine patches in irrigated and non-irrigated dairy pastures in the South East of South Australia was u ndertaken with repacked and monolith lysimeters 1 m deep, and with monolith lysimeters 150, 300 and 450 mm deep. The aim was to quantify differences i n measurements of drainage and nitrogen fluxes for these different lysimete rs. Drainage of water and N flux were found to vary significantly between t ypes and depths of lysimeters. Drainage volumes in repacked lysimeters were 78% and 33% more than in monolith lysimeters in irrigated and non-irrigate d paddocks, and N fluxes were 5 and 3 times higher in repacked lysimeters r espectively. The results indicate that lysimeter estimates of recharge rate s and N fluxes to water tables are best determined by leaching studies whic h are longer term, and use deep monolith lysimeters. Shorter term studies a nd the use of shallow or repacked lysimeters have potential to distort conc lusions.