Know Your Soils

Knowing your soils is very important.  Having quality information about your soils can help you overcome some of the biggest yield limiting factors on your farm.  We look at the things that will affect your yields, and there are many things you cannot control; things like rainfall, growing degree days, soil texture, and soil temperature.  There are also things we can control; like fertility, crop varieties, weed control, insect control, and disease control.  These are the things you can manage, and these are the things you need to concentrate on.

Fertility is probably the most important thing that you can control, when targeting high yields on your farm.  Knowing how much fertilizer and what type of fertilizer you should use is crucial to what your yield limit is. Firstly, you need to know the amount of nutrients left in the soil when determining the amount and type of fertilizer you need. This can be done by doing soil tests on your farm.  Soil tests will give you crucial information about pH, organic matter (OM), Cation Exchange Capacity (CEC) and all the macro (N, P, K, S) and micro (B, Cu, Zn, Cl, Mg, etc) nutrients you have in your soil.

Organic matter is important because the higher your OM, the more nutrient cycling you will have, and the more N, P and S you can expect to get each year.  OM is also important in determining how much water holding capacity a soil has.  Soils high in organic matter have the ability to hold more water which can be a huge advantage during dry cycles and drought conditions.  Typically the higher your organic matter content, the higher the yield potential the field has.

pH is also a measurement you get by doing a soil sample.  This gives you a measure of how acidic or basic your soil is.  Different plants favour different pH’s and you can get an indication of what the pH is by looking at the native vegetation in and around the field.  For most agricultural crops the ideal range of pH is between 6.5 and 7.5.  Some crops however will do really well in basic pHs like Alfalfa, and some plants like blueberries or Saskatoon berries will do well in acidic conditions.  pH is also important when looking at the availability of your nutrients.  As you get further away from neutral (7) pH you will typically have less nutrients available.  However, some nutrients are more available at lower pHs, and some are more available at higher pHs. Your agronomist can help you sort through these details with your soil test reports.  pH will also affect how quickly some herbicides will break down in the soil, so it is something you should always be looking at.

The final thing that you need to look at is how much macro and micro nutrients are left over from last year’s crop, and what has been lost. When crop yields are high or higher than you had fertilized for, you must realize that your crop may have removed a great deal of available nutrients.  There may not be much for reserves left in the soil, and you should plan on satisfying the crop requirements for next year.  The other thing that may leave you with fewer nutrients is loss to the environment. Environmental losses occur through volatilization (gassing off) or more likely moving out of the rooting zone (leaching).  Luckily not all nutrients are lost this way.  Only nutrients that are water soluble are lost to leaching these include Nitrogen, Sulfur, Chloride, and Boron.  Soil testing will tell you exactly what is left in your soil, and you can now work with your local Cavalier Agrow agronomist to determine a plan to maximize your yield and profit on your farm.


By Duane Horvey