A common question often asked about no-till is whether any nutrient stratification occurs due to a lack of soil mixing. Many no-tillers wonder if stratification is a problem for effective crop access to soil nutrients.
Nutrient mobility plays a critical role in evaluating stratification. Nutrients that end up in a chemical form that is mobile, like nitrate and sulfate, generally are less stratified. Less mobile nutrients, like phosphorus and potassium, bind to the soil and are primarily found in the top 6 inches, regardless of tillage practices.
In research trials with no-till where both phosphorus and potassium were measured, these nutrient were generally found at a higher concentration in the top 2 to 3 inches of soil relative to conventional tillage.
In fact, some studies found the phosphorus and potassium accumulated at the same depth, which also happened to be the depth where the fertilizer had been banded. This is an interesting finding and confirmation about a lack of movement with these nutrients.
Did stratification impact nutrient uptake? Studies in northern Alberta and central Montana revealed that when nutrients were stratified in no-tilled soils, stratification did not impact the uptake of the nutrient by the next crop in the rotation. In one instance, phosphorus uptake was actually improved in the no-till plots. This is good news if you are concerned about soil nutrient changes with no-till.
Why would stratification of nutrients in no-till fields not impact crop uptake? First of all, many research projects have…