Soil nutrient studies

Soil nutrient studies have been conducted for agronomic and environmental purposes, in several regions of British Columbia: Hullcar Valley (annually from 2016-2025), the Lower Fraser Valley (2012 and 2005), the Okanagan-Similkameen Valley (2007, 2020), Vancouver Island (2020) and selected areas of the Thompson River Regional District (TNRD, 2020).

What's new

A Decade of Post-Harvest Nitrate Monitoring in the Hullcar Valley

This report reviews a decade (2016-2025) of post-harvest soil nitrate monitoring in 40 – 50 agricultural fields within the Hullcar Valley.

Highlights:

• Mean post-harvest soil nitrate throughout the 2016-2025 monitoring period ranged from 35-57 kg NO₃-N ha^-1 which is acceptable for a properly fertilized crop. The mean post-harvest soil nitrate is below a provincial 100 kg kg NO₃-N ha^-1 threshold
• Over the study period, only 4.6% of the 40-50 fields had post harvest nitrate levels exceeding 100 kg NO₃-N ha^-1 in the top 30 cm. Notably, no field exceeded the 100 kg NO₃-N ha^-1 provincial threshold for more than one year
• Approximately two-thirds of the nitrate was consistently in the top 30 cm
• Annual crops generally had higher residual nitrate compared to the perennial forage crops in the 0-90 cm profile
• A benchmark study from fall 2016 to spring 2020 showed downward redistribution of soil nitrate mainly from the 0-30 cm to 30-60 cm soil layers during the non-growing season. Despite this, soil nitrate remained very low below 60 cm
• From 2016 onwards, mean soil nitrate levels declined but have been increasing in recent years

2024 Soil 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
• Post-harvest soil sampling after the 2024 growing season was completed on 50 fields lying above Aquifer 103 in the Hullcar Valley of the North Okanagan to a 90-cm depth
• The area-weighted average soil nitrate value for the entire sampling area for 2024 was similar to 2023 (76 and 78 kg NO3-N ha-1, respectively), as was the median soil nitrate value (62 and 62 kg NO3-N ha-1, respectively)
• Among the fields sampled, 62% of the nitrate in the sampled 90 cm of soil was found in the 0-30 cm layer on average, while 21% and 16% was found in the 30-60 and 60-90 cm layers, respectively.

Read the final report:

• NEW A Decade of Post-Harvest Nitrate Monitoring in the Hullcar Valley (PDF, 1.3 MB)
• NEW Soil Nitrate Survey of Agricultural Fields in the Hullcar Valley in 2024 (PDF, 291 KB)

Past reports:

• 2023 Post Harvest Nitrate Survey - Final Report (PDF, 277 KB)
• 2022 Post Harvest Nitrate Survey – Final Report (PDF, 312 KB)
• 2021 Post Harvest Nitrate Survey – Final Report (PDF, 287 KB)
• 2020 Post-Harvest Nitrate Study - Final Report (PDF, 274 KB)
• 2019-20  Post-Harvest Nitrate Study - Final Report (PDF, 1.7 MB)
• 2018-19  Post-Harvest Nitrate Study - Final Report (PDF, 1.3 MB)
• 2017-18  Post-Harvest Nitrate Study - Final Report (PDF, 1.7 MB)
• 2016 Post-Harvest Nitrate Study - Final Report (PDF, 2MB)
• 2016 Post-Harvest Nitrate Study - Questions and Answers (PDF, 486 KB) Updated December, 2017

Raw data:

• 2019 Post-Harvest Nitrate Study - Individual Field Test Results (Excel Spreadsheet, 177 KB)
• 2018 Post-Harvest Nitrate Study - Individual Field Test Results (Excel Spreadsheet, 131 KB)
• 2017 Post-Harvest Nitrate Study - Individual Field Test Results (PDF, 2 MB)
• 2016 Post-Harvest Nitrate Study - Individual Field Test Results (PDF, 2.4MB)
• 2016 Post-Harvest Nitrate Study - Individual Field Test Results (Excel spreadsheet, 153 KB)

• 2019 Post-Harvest Nitrate Study - Benchmark Test Results (Excel spreadsheet, 50 KB) 
• 2018 Post-Harvest Nitrate Study - Benchmark Test Results (Excel spreadsheet, 35 KB) 
• 2017 Post-Harvest Nitrate Study - Benchmark Test Results (Excel spreadsheet, 291 KB)
• 2016 Post-Harvest Nitrate Study - Benchmark Test Results (Excel spreadsheet, 153 KB)

Soil Nutrient Study 2020

The Soil Nutrient Study 2020 (PDF, 1 MB) was conducted in selected areas of the Okanagan-Similkameen Valley, Vancouver Island and the Thompson River Regional District (TNRD)

Previous Studies

• 2012 Fraser Valley Soil Nutrient Survey (PDF, 1.2 MB)

2012 Fraser Valley Soil Nutrient Survey - Results by Crop Group:

• Blueberries (PDF, 427 KB)
• Raspberries (PDF, 416 KB)
• Field Vegetables (PDF, 268 KB)

• 2007 Okanagan Agricultural Soil Study  (PDF, 1.1 MB)
• 2005 Fraser Valley Soil Nutrient Study  (PDF, 1.5 MB)