Effect of treated farm dairy effluent on E. coli, phosphorus and nitrogen leaching and greenhouse gas emissions: a field lysimeter study

Purpose Land application of farm dairy effluent (FDE) to pasture soils is the preferred practice in New Zealand. Recently, a new FDE treatment technology has been developed to recycle the water for washing the yard Cameron and Di (J Soils Sediments 2018 ). Here we report a lysimeter study to compare the leaching losses of Escherichia coli , phosphorus (P), and nitrogen (N) and emissions of greenhouse gases from the treated FDE compared with the untreated original FDE. Materials and methods Lysimeters were collected from a Balmoral silt loam soil (Typic Dystrudept, USDA) and installed in a field trench facility. Treatments included (1) treated effluent (TE), (2) a mixture of TE and recycled water (M), (3) untreated original FDE (FDE), and (4) water as control. The effluents were applied at a surface application rate of 24 mm on each lysimeter in May and again in September 2017. Measurements included leaching losses of E. coli , total phosphorus (TP), dissolved reactive phosphorus (DRP), total mineral nitrogen (TN), ammonium-N (NH 4 + -N), and nitrate-N (NO 3 − -N); emissions of nitrous oxide (N 2 O), carbon dioxide (CO 2 ), and methane (CH 4 ); herbage yield; and N uptake. Results and discussion The results showed that E. coli , TP, and DRP leaching losses from the TE were 1.31 × 10 10 cfu/ha, 0.26 kg P/ha, and 0.009 kg DRP/ha and from M treatments were 6.96 × 10 8 cfu/ha, 0.18 kg P/ha, and 0.004 kg DRP/ha, respectively, which were significantly ( P