Update from the Field: Get the Dirt on Your Soil
Posted by Dave Dyson, Agronomist on October 31, 2019
Following the season, it is important to sample your soils to best understand your pH and nutrient levels. In our busy lives, it is hard to take a few days and hit the pause button while waiting for the soil test results. However, waiting these few days can be the difference between dumping your money down the drain or applying the right product, at the right rate, in the right place. Measuring and correctly adjusting soil pH is an important step to having a successful crop season next year.
Soil pH is defined as a measure of acidity and alkalinity in the soil. The range of pH levels varies from 0 to 14, with 7 being neutral. The pH level is calculated by measuring the activity of hydronium ions in a soil/water solution. The pH level usually falls within a range of 3-10 pH. Acid soils have a pH below 7, and alkaline soils have a pH above 7. This is a negative logarithmic scale, so as pH increases from 5 to 6, the number of hydronium ions decreases by a factor of 10. This is where changing the pH a little is good, but changing it too much can cause some real damage to your field. I always recommend a soil sample before thinking about amending the soil’s pH. We must know where our starting point is before launching up or down the pH scale.
One might ask the question “why are we so worried about pH in the soil?” Soil pH is considered a master variable in the soil as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of nutrients and influencing the chemical reactions they undergo. The essential nutrients for crop production are most available in the soil between the 6-7 pH range, Figure 1. Correcting the soil pH is like steering a ship; small course changes are much more manageable.
Figure 1: Nutrient availability vs. pH chart by Purdue University.
Normal activity in a cropping system will drive soil pH lower. Soils become acidic when elements such as calcium, magnesium, sodium, and potassium held by the soil are replaced by hydrogen ions. Soils formed under conditions of higher annual rainfall are more acidic than soils formed under more arid conditions. Nitrogen applications affect pH levels as well. The greater the nitrogen rate, the greater the soil acidification.
There are two ways soil pH can be increased. The first method is with adding ag lime. Ag lime requires specialized equipment to apply to the soil and may take up to four years to see the full benefit. The second option is adding NutraLime® DG or NutraLime OP, which is approved for organic production (Figure 2). These products have a uniform size and weight which make it possible to be spread with fertilizer. Due to their dispersing granule technology, which increases their nutrient-use efficiency and in-season availability, NutraLime DG or NutraLime OP can be spread at a lower rate of 200-300lb/ac. As a result, they are excellent options to blend and apply with fertilizer every year to keep your pH from the catastrophic high and low swings.
| PRODUCTS MENTIONED | PRODUCT SHEET |
| NutraLime® DG (Hi-Cal) |  |
| NutraLime DG (Hi-Mag) | |
| NutraLime OP (Hi-Cal) OMRI Certified |  |
| NutraLime OP (Hi-Mag) OMRI Certified | |
Figure 2: NutraLime product offering and the corresponding information.
In conclusion, be patient this fall as you wait for your soil sample results. The insight you receive will help guide your fall management decisions and save you money in the long-run. Remember to keep your soil’s pH between 6-7. Within this range, essential nutrients will be in a useable form for the plant. Contact your local representative from The Andersons for more information about NutraLime DG or NutraLime OP.
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Dave Dyson is a regional agronomist for The Andersons’ Farm Centers which are located throughout Ohio, Michigan, and Indiana. He is an Indiana native and grew up on a dairy farm in Miami County. A graduate of Purdue University with a degree in Crop & Soil Science, Dave has a deep knowledge of various agronomic topics and is committed to helping growers improve their crops. If you have any questions, Dave can be reached at david_dyson@andersonsinc.com.
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