Spring, Summer, Fall or Winter? According to Dale Cowan of Agri –Food Laboratories the right time is directly after harvest. The next best time would be spring when soil conditions allow. The only exception is nitrate sampling. Dale also mentioned that after the wheat crop this year. Post harvest sampling would ideal for growers who have manure or lime to spread or who want to get back in a routine. The turn around time should be about 5 working days.

For consistency, it would be good idea to soil sample the same time each year and following the same crops in the rotation. Sampling every 3 years is adequate for most soils. You may need to sample coarse textured soils and problem spots more often. This is especially true when certain crops remove high amounts of nutrients like potassium in alfalfa or if a particular fertility problem occurs. It’s a good idea to sample good areas of the field separately from the poor. Also take separate samples from different soil types and if different crops are to be grown.

Watch out for sampling to deep, 6 inches is considered the correct depth. One should use a stainless steel probe and stay away from products that could contaminate your sample. Use a clean plastic pail to mix your samples in. Throw out any foreign objects such as seeds or stones in your sample. Don’t sample to close to a gravel road because of dust. Also stay away from dead furrows, highly eroded knolls, and where lime or organic waste has been piled. If curious take a separate sample of these areas.

When sampling, get a composite sample for every 25 acres or less. The number of probes or cores should be a minimum of 20 per sample. These are some suggestions to review before sampling is to done. If you have any questions or fields to be sampled, please contact one of the crop specialists at your local coop.

Mike Parker CCA-ON