USING LAST FALL’S SOIL TEST FOR THIS SPRING’S BEST RESULTS
You got your soil test results back. You know how to properly read them. So now what?
You use them for #plant23.
Do you need more nitrogen? Phosphorus? Potassium? Your soil results will help you properly select your fertilizer types and amounts.
Let’s explore how to use your soil results and recommendations to correct issues in your fields.
CORRECT AND IMPROVE YOUR SOIL PH
Soil pH is a measure of the active acidity (or alkalinity) in the soil. Most crop soils prefer pH to be approximately 6.0-7.0.
Soil test results will report pH in two ways: soil pH and buffer pH. The soil pH measures the active acidity, or hydrogen ion concentration in the soil solution. The buffer pH measures the reserve acidity in the soil – which helps measure the soil’s resistance to change when lime is added. The higher the buffer pH, the easier it will be to correct your soil’s pH levels.
If your soil falls above the recommended pH level, you can apply calcitic limestone. Limestone is a very common purchase for farmers and can be applied with a granular spreader, or incorporated into the soil. A 1.0 improvement in pH requires approximately 40 pounds of lime per 1,000 square feet.
To accurately determine the amount of calcitic or dolomitic lime you need based on your soil’s pH levels, review your base saturation percentage. As base saturation increases or decreases, pH follows suit. Base saturation can also help you understand calcium, magnesium, and potassium levels in your soil.
UNDERSTANDING MACRONUTRIENT LEVELS: N,P, AND K
Some of the more complex soil test results include recommendations for raising your nitrogen (N), phosphorus (P), and potassium (K) levels. The type of test you used – Bray 2 or Mehlich 3 – will affect the recommendation amounts. Mehlich 3 will likely show higher amounts of macronutrients in your soil and will give a recommendation in lbs/ac, while Bray 2 shows a recommendation for Phosphorus in P2O5.
A soil test takes into account all forms (organic and inorganic) of N, P, and K. This does not represent a nutrient level that’s available for uptake by the plant. Rather, it’s the level of each source available in the soil. Because of this, be sure you’re following the soil report’s recommendations, as well as those from your local extension office, such as the Tri-State Fertilizer recommendation booklet.
After you’ve reviewed the recommendations for each nutrient, there are many different fertilizers that can address your nutrient needs. Work with your AgriGold agronomist to find the best fertilizer, plus advice on how it should be applied to your fields.
DON’T FORGET MICRONUTRIENTS
Although micronutrients aren’t at the forefront of plant needs and sometimes aren’t available on soil test results, it’s still important to review your sulfur, boron, and zinc levels. These can help ensure proper soil health and play a role in crop potential.
If your soils need sulfur, it’s recommended you do a pre-plant application of sulfate using a planter, or make a side-dress application.
Boron is very similar to nitrogen in terms of crop use and its cycle in the soil. Thankfully, if you have an urgent boron need, it’s quite easy to get the nutrient into the plant using a foliar fertilizer.
Meanwhile, zinc is quite difficult to get into the plant. It’s important to closely monitor zinc needs, as it plays a role in chlorophyll production and plant tissue growth.
BUYING AND APPLYING FERTILIZER
Choosing the right fertilizer for your soil is important for proper crop growth and next growing season’s fertility. To select a fertilizer that provides the best group of nutrients based on your soil test recommendations, look at the pounds of N-P-K your results recommend.
For example, if the recommendations show 20 lbs N + 5 lbs of P + 10 lbs K, you need to find a fertilizer with the same ratio. A 20, 5, and 10 ratio divides down to 4, 1, 2. So you will need a fertilizer that gives you nutrients in that specific ratio.
Once you’ve decided on the fertilizer you’re going to apply, make sure you know the best way to incorporate it into your soil for the best nutrient uptake. Work with your agronomist and local extension office to buy the amount that matches your specific nutrient poundage needs for each field. This ensures your soil is getting the proper nutrients, and you save time and money on inputs.
STILL HAVE QUESTIONS? WE CAN HELP.
To grow healthy plants and achieve high yields, you need to understand – and use – soil test results. If you have any questions about soil testing and fertilizer options, head to our Agronomy Article Library to learn more, or reach out to your local AgriGold agronomist for farm specific questions.
