With harvest completed many farmers are planning next year’s crop. This often means planning crop rotations, seeing which seed treatments (if any) you’d like to apply, and determining what fertilizer applications you will be applying. Many of you have also been told that you should do some soil testing before planning next year’s crop. But why should you do it? In this week’s edition of Growing Possibilities, we will discuss the benefits of soil testing and why you should do it.
There are several important nutrients in the soil, macro-nutrients like nitrogen (N), phosphorus (P) potassium (K) & sulfur (S) and micronutrients like Ca, Mg, Cu, Zn, Mo, etc. In order to have a healthy crop, the soil must have enough nutrients to be fertile. Soil testing measures the nutrient and pH levels in the samples, giving you vital information for deciding how much and what kind of fertilizer your fields need. Knowing your nutrient levels in the fields reduces the likelihood of over fertilizing and prevents you from buying expensive fertilizer that you don’t need (1). Soil testing should be done yearly to help track nutrient levels and to ensure that your current nutrient application is ideal for your fields (3).
This is particularly important after a drought year. During a drought, crops don’t get enough water to grow to their full potential, which means the plants have less biomass and fewer yields. Since the plants are smaller, they use fewer nutrients from the soil. This means more N, P, K and other micronutrients are left in the soil after harvest than normal years. The N and K will be readily available for uptake in the following spring, but the P likely will not be. Phosphorous reacts with minerals (like Ca, Mg, Al, Fe) in the soil, making it unavailable for the plants to use. This process quickens the colder the weather gets, so less P will be available for the plants in the spring when compared to the fall (2).
Since a large portion of the P in the soil is unavailable for plants by spring, farmers often have to apply P fertilizer every year to ensure the plants have access to enough P. But you are not required to rely on P fertilizers alone. The P solubilizing PGPR (e.g., XiteBio® Yield+) make soil-bound P available for plant uptake. This creates more plant available P from the natural phosphate reserves present in the soil or increasing the efficiency of fertilizer applied. Because P is one of the most expensive inputs you use on your crops, making sure you don’t apply more then you have to can save your cost of production, especially a year like this when cost of fertilizer is going through the roof.
References
- https://www.agrocares.com/2020/11/02/5-reasons-to-test-your-soils-2/
- https://www.manitobacooperator.ca/news-opinion/news/soil-testing-even-more-crucial-after-drought-year/
- https://www.cropnutrition.com/resource-library/soil-testing-when-why-and-how