ISSUE 15 August 15, 2002
HARVEST AND SOIL TESTING GO HAND IN HAND
Wheat, barley, and canola harvest are underway in parts of North Dakota and with it comes the first opportunity to look forward to next years crop. Soil sampling may begin as soon as the early crop is removed. The adjustment on soil test reports known as the "sampling date adjustment" is valid for all three of our early crops, including canola. I have been leery of recommending early sampling following canola due to the possibility of higher N release following harvest than from wheat or barley, but a recent residue study including canola has suggested that no special treatment is necessary to delay sampling following this crop.
The question of whether to sample before or after tillage is largely up to the farmer. Some practically follow the combine with a tillage tool, while others do not till at all. Sampling before tillage results in a more consistent 0-6 inch core for P, K and soil pH, while tillage reduces the possibility of fire hazard to tall residue. In drier areas of the state, samplers need to be aware of fire possibilities. Many sampling vehicles sit high enough off of the ground to avoid a danger, but lower profile samplers may need to wait until after a rain to safely travel the field.
Delay in sampling often results in spring guess work in nitrogen recommendations. There is no need to wait until September to begin this important activity.
NDSU Extension Soil Specialist