Fall is a good time to do soil tests. Growers may have a extra few hours to take samples, unlike in spring. And with results and recommendations in hand before winter, growers have more time to plan their fertilizer programs for 2012, to order fertilizer, and to take advantage of reduced pricing opportunities that may occur.
The ideal time is to take samples when soil temperatures drop below 7 C. Because microbial processes in the soil slow down as temperatures cool, sampling late in the fall will provide a better indication of what nutrient levels will be next spring.
Growers can use results from soil nutrient analysis to determine if the fertilizer rates they have been applying are in line with current industry recommendations.
Which lab to choose? Different labs may use different chemical extraction methods for determining nutrient levels in soil samples, so labs will not always come up with the same recommendations. If you already have a favorite lab, it’s important to send samples to the same lab for year to year comparison of test results. Many labs base recommendations for next year on soil test analysis plus yields for the current year. If, for example, wheat yielded 50 bushels per acre, the lab will consider the nutrients removed by that wheat crop when setting canola fertilizer recommendations for next year. The CCC factsheet “Understanding Soil Test Recommendations” has more information.