Soil nutrient studies

Soil nutrient studies have been conducted for agronomic and environmental purposes, in three regions of British Columbia: Hullcar Valley (annually from 2016-2019), the Lower Fraser Valley (2012 and 2005), and the Okanagan-Similkameen Valley (2007).

2019-2020 Post-Harvest Nitrate Study: Hullcar Valley

Highlights

Monitoring the year-to-year trends of post-harvest soil nitrate is useful for improving the efficiency of nitrogen use
In the fall of 2019, 39 agricultural fields over or near the Hullcar Aquifer 103 were sampled for a Post-Harvest (Soil) Nitrate Test (PHNT) to compare with 2018 results
The area-weighted average PHNT of the overall study area was similar in 2019 compared to 2018 (78 to 75 kg NO₃-N ha^-1, respectively), as was the median PHNT in 2019 compared to 2018 (70 to 68 kg NO₃-N ha^-1, respectively)
The area-weighted average and median PHNT increased for fields cropped with corn silage while these values decreased for fields crop with alfalfa/grass
Among the fields sampled, 51% of the nitrate in the top 90 cm of soil was found in the 0-30 cm layer on average, while 22% and 27% was found in the 30-60 cm and 60-90 cm layers, respectively.
From October 2019 to April 2020, six sites were monitored more intensively as benchmark sites, nitrate concentration decreased in the 60-90 cm depth in one of the six benchmark sites over the course of the study period, indicating leaching of NO₃-N below the 90-cm depth