By Quinton Cubbon, BSc, AAg, Crop Extension Specialist, Regional Services Branch, Ministry of Agriculture, North Battleford
and Kim Stonehouse, MSc, PAg, Crop Extension Specialist, Regional Services Branch, Ministry of Agriculture, Tisdale
Harvest is in full swing across the province, and the southern parts of the province may even be close to wrapping up for the season and beginning fall work. With fall work comes the decision of whether to soil test for the following season. It may be difficult to predict how many leftover nutrients are in the soil for next year's crop. The weather in Saskatchewan has been unpredictable, with a cool and wet June followed by a scorching hot July with minimal rainfall. The weather has been challenging, as yields may not meet expectations, even though the crop canopy may have indicated otherwise.
in the field avoiding nonrepresentative areas.
Over the past few years of dry conditions, there has been an increase in the carryover of phosphorus and potassium, as these nutrients were not fully utilized by the crop. However, sulfur and nitrogen are less predictable because they are mobile within the soil. Because of this, both are prone to leaching and nitrogen has the potential to suffer further losses due to immobilization, volatilization, and denitrification.
In June, the high amount of moisture may have led to greater nutrient uptake and higher leaching. The moisture helped move nutrients into the rooting zone, making them available for plant uptake. By July, with minimal moisture in many parts of the province, the high plant matter from June might have resulted in unexpected high losses of fertility. Utilizing a soil test will help determine how many nutrients are left for the following season. Soil testing can commence once the soil temperature has dropped below 10°C, as this reduces the risk of nitrogen mineralization. For accurate results, it is important to take soil samples to a depth of 6"-12" and to sample 15-20 times throughout the field, while avoiding irregular areas such as dips and hilltops.
The test results can help plan for the next growing season by indicating the remaining available nutrients and identifying potential deficiencies. Fall soil testing can assist with nutrient management as it provides an accurate depiction of the nutrients remaining in the soil. Some nutrients may be present in higher amounts, requiring less application of fertilizer which can reduce expenses and limit the risk of over-application.
For more information on fall soil testing, please contact the Agriculture Knowledge Centre at 1-866-457-2377 or your local crops extension specialist.