Proper soil sampling needed

Agri-Food Laboratories of Guelph has received a significant number of soil samples recently where the accompanying paper work asks for analysis of organic matter, pH, and nitrogen.
OMAF staff and the soil lab reps are concerned producers, retailers, and/or crop consultants are not conducting proper soil sampling for nitrogen testing.
For the proper analysis of organic matter, pH, P, and K, a six-inch soil core depth is required.
However, for proper nitrate sampling, it is essential that a 12-inch core sample be taken.
If analysis is required for various components as outlined above, then two separate soil samples are required–one from six inches and one from 12 inches.
The recommendation systems developed for Ontario are calibrated to the appropriate soil sample depth.
To have the correct information and get meaningful results, ensure you are matching the sampling technique to the information you are seeking.
To obtain a representative sample for a field, take at least 20 12-inch cores for each 10 ha (25 acre) area. Mix the cores thoroughly and send a composite sample to the lab for analysis.
Samples must be kept cool (refrigerated or frozen) and sent by courier to the lab. There usually is a two-three day turnaround for the results.
Where obvious differences in soil type or topography are evident in a field, it is advisable to take separate soil samples for these areas.
Although this increases the lab costs, it can significantly impact the amount of nitrogen fertilizer you may need to apply.

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