Have you got your soil tests done for the year? If not, that’s just fine, as late fall is actually a great time to test soil nutrient levels, says Ross McKenzie, now-retired soil scientist (from Alberta Agriculture).
Without a soil test to guide the decision, farmers are choosing fertilizer rates “by guess and by golly,” Mckenzie says, even when that bill can be over $200,000 or more per year.
Some farmers end up using similar rates and amounts of fertilizer year over year, and so begin to think they know their soils, making soil testing a cost, not an investment. But Mckenzie says that that can, over time, cause some major issues. Crops are yielding more than they used to removing more pounds of each nutrient per acre, for example, and the western Canadian crop mix has changed to include big sulphur using crops, for example.
Fall is really the perfect time to sample, as soils are cooling later into fall, slowing down microbial activity. This means that what’s there now is likely to be there in early spring. Soil test taken in early September, in contrast, could be subject to quite a bit of nutrient change before freeze up (in perhaps warmer years).
In the video below, Mckenzie explains the value of soil testing, and how proper handling of soil samples once you’ve got them leads to the most accurate soil test results: