Effect of No-till, Conventional and Vertical Tillage Practices on Nitrate and Phosphorus Losses in Southern Ontario.

Effect of no-till, conventional and vertical tillage practices on nitrate and phosphorus losses in Southern Ontario C. S. Tan1, T. Q. Zhang1, K. Stammler2 and M. Dick2 1Agriculture & Agri-Food Canada, GPCRC, Harrow, Ont. Canada, N0R 1G0 2Essex Region Conservation Authority, Essex, Ont. N8M 1Y6 ASA/CSSA/SSSA International Annual Meeting, Oct. 22-25, 2017, Tampa, Florida, USA Concerns have been raised with respect to the losses of phosphorus (P) and nitrogen (N) to surfaces waters from tile-drained lands under different tillage treatments. There have been little data collected to date that consider the entire annual nutrient losses for both surface & tile drainage water from agricultural lands as impacted by various tillage treatments and drainage systems. In particular, there is not much information available on pathway distribution between surface and sub-surface tile drain to tillage practices. Studies were conducted on clay loam soils at two different field sites to evaluate total N and P losses under various tillage management practices with a corn-soybean rotation. The experiment at site 1 was conducted from 1995 to 1998, only subsurface tile drainage water quality was measured under control drainage (CD) and regular free drainage (RFD) with both no-tillage (NT) and conventional tillage (CT) practices. The new experiment at site 2 was conducted in 2016, both surface and subsurface tile drainage water quality were measured under free drainage with both NT and vertical tillage (VT) practices. The experiments conducted at both sites were equipped with automatic flow volume measurement and sampling systems. The results for site 1 showed that the CD system under NT reduced total P and N losses by 25 % and 16 %, respectively, compared to RFD. However, the CD system under CT reduced total P and N losses by 13% and 7 % relative to RFD, respectively. There was subtle yield increase from CD system under both NT and CT treatments. The preliminary results for site 2 indicated that the VT produced 13 % less total flow volume than the NT treatment. The VT also decreased flow weighted mean dissolved reactive P (DRP) and nitrate concentrations by 8 and 19 %, respectively relative to NT treatment. Therefore, the VT reduced DRP and nitrate losses by 21 and 30 %, respectively, relative to NT treatments. There was 5.4 % yield increased from vertical till treatment.