I heard recently that only an estimated 20% of the fields across the Canadian Prairies are soil sampled. This is a surprisingly low number to me, as soil testing is the base on which many components of a farm plan for the year are built. What’s worse is that of the 20% of fields sampled, many are likely not sampled properly or analyzed fully. In my mind, a soil sampling routine is a first step in maximizing crop outputs to feed a growing population.
If you’re thinking of soil testing, it’s important to first put a plan together. To start, there are many different types of soil test strategies — random, benchmark, zone — I may delve into these at a later date, but talk to your agronomist (or watch this video) and determine which strategy is going to best suit you and your farm’s needs.
The first and foremost benefit of a soil test is the ability to understand what is in your soil. My favorite metaphor is to look at your fields like a bank account, and a soil test as the statement. You can’t just keep pulling out nutrients without putting a sufficient amount back or eventually you are going to run into problems. What’s more, without an actual measure now and again, estimating crop removal could lead to some wrecks — just like we under estimate our spending each month, wet, dry or ideal conditions can impact removal or losses, skewing those estimates. A soil test, at least now and again, will take out that guess work.
Once you have a handle on nutrient levels, it’s important to apply fertilizer based on targeted yields. This starts with the macronutrients (N,P,K, S), of course, but don’t forget to look at your micronutrients and monitor their levels as well. Depending on a field’s history or crop rotation, one or more micronutrients can get depleted, like sulpher, manganese or copper.
Organic Matter is another very important component to look at on a soil test, as this is an important source of nutrients and can help things like soil water holding and nutrient holding capacity. It also releases nutrients back into the available form every year through mineralization. You can have an additional 7 lb per percent organic matter of nitrogen released every year available to your crop (Note: 7 lb is a general rule, actual mineralization is going to vary based on conditions).
The soil pH number is a way of telling if your soil is more or less acidic. This is important for a number of reasons, a big one being you getting the inside scoop on whether your nutrients could become less available to the plant. For example, in a higher pH soil, say one that is 7.9, phosphorous is going to become much less available to crops roots than a soil that is 6.8 pH, for example.
The Cation Exchange Capacity (CEC) is a fancy way of determining if you have a heavy or clay soil vs. a light or sandy soil. This is important for a number of reasons, but one key reason is to help determine safe seed-placed fertilizer amounts. A heavier soil can have more fertilizer safely put with the seed than a lighter one.
At the end of the day, a soil test that has been taken and properly analyzed might be one of the best investments you make all year. Do you have an under-performing field? Your answer could just be a soil test away.