Update from the Field: Profitability & pH
Posted by Dave Dyson on November 14, 2017
Talking to clients about liming or fixing a pH problem can be a little dull or boring. It is definitely not as appealing as a fertilizer or chemical recommendation. You may not see the full effect of your lime application for 2-4 years, but once you get your pH within a good range (between 6 and 7), the results are sure to impress.
Soil pH is defined as the measure of acidity and alkalinity in the soil, and pH levels range from 0 to 14, with 7 being neutral. When we measure the activity of hydronium ions in a soil-water solution, it typically falls within the range of 3-10 pH. Acidic soils have a pH below 7 and alkaline soils have a pH above 7. This is a negative logarithmic scale, so as you increase from 5 to 6 pH you have a drop in the amount of hydronium ions by a factor of 10. This is why changing the pH slightly is good, but too much can cause real damage to your farm. I always recommend a soil sample before thinking about amending the soil’s pH. We have to know our starting point 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 as it affects many chemical processes. It affects plant nutrient availability by controlling the chemical forms of various nutrients and influencing the chemical reactions they undergo. In The Andersons Farm Centers’ territories, with the exception of blueberries, all of our crops grow best between a pH between 5.5 and 7 (figure 1). The nutrients we need to grow our crops are most available in soils with a pH between 6 and 7(figure 2). Correcting soil pH is like steering a ship; small course changes are much more manageable.
Normal activity in a cropping system will drive soil pH lower. Soils become acidic when basic 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.
It is important to keep our soil’s pH between 6 and 7 so essential nutrients will be in a useable form for the plant. There are two ways we can increase the pH. The first is through the application of ag lime, which requires specialized equipment. It may take up to 4 years to see the full benefit of ag lime, but it will have a long lasting effect in the soil. The second option is NutraLime DG pelletized limestone. This product has a uniform size and weight which makes it possible to be spread with fertilizer. At a rate of 200-300 pounds per acre, NutraLime DG pelletized limestone is an excellent product to apply with fertilizer every year to keep your pH from catastrophic high and low swings.
Summary:
- pH is the lynchpin that connects fertilizer with nutrients available to the plant
- Soil pH should be maintained between 6-7
- Use NutraLime® DG every year to maintain a constant pH
Figure 1: pH range most suitable for different crops
Figure 2: Nutrient availability vs. pH chart by Purdue University
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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.
NutraLime is a registered trademark of The Andersons, Inc.
