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Soil Acidity Solution

Posted Dec. 1, 1997

Introduction. Hello, my name is Jeff Ball the new soil fertility and crops specialist on the NF3 team along with Clay Wright, Dan Childs, Grant Huggins, Cat Taylor, and Matt Mattox. I am replacing Randy Bowman who left in March to pursue a career with Texas A&M.

I began work in October and have greatly enjoyed interacting with the other specialists. For the previous two years I have been an agronomist for Farmland Industries and my background is primarily in wheat, soybeans, corn, grain sorghum, alfalfa, sunflowers, and some experience in bermudagrass production.

Most of my experience has come from working with row crop producers out of a local cooperative in northeast Kansas. I received my education from OSU, where I also obtained considerable experience in soil fertility research. I am really excited about being a part of the Noble Research Institute and I am looking forward to the opportunity of working with cooperators in solving their production problems.

Liming Wheat. One of the most common and overlooked limitations in crop production is soil acidity. With the cultivation of the land and the harvest of high yielding crops, soil acidity has gradually increased and is becoming a problem throughout the region. As soil pH decreases, metal toxicity (aluminum and manganese) increases. Metal toxicity is the major contributor to poor plant performance and yield loss in low pH soils. These metals remain in a solid form and are unavailable for plant uptake at a pH above 5.5. However, as pH decreases these metals become more soluble and available for plant uptake.

Aluminum and manganese toxicity limits the plant's ability to absorb essential nutrients, such as phosphorus, which disrupts the normal growth processes in the roots and above ground portions of the plant. Other problems, such as poor herbicide performance and microbial populations, can also be affected by soil acidity.

The first step in correcting a soil acidity problem is to soil sample. Soil testing not only recognizes nutrient levels, it also identifies the pH level and buffer index. Soil pH is a measurement of the active acidity and the buffer index is an estimate of the reserve acidity or the soil's resistance to change. Use this measurement to determine the amount of lime that will be needed to move the soil pH to a more productive level.

Liming is the only effective way to correct soil acidity. The active ingredient in lime is calcium and/or magnesium carbonate (CaCO3, MgCO3). Lime works at lowering the soil's reserve acidity by reducing the amount of hydrogen ions (H+) tied to the soil and increasing the concentration of nonacidic elements such as calcium and magnesium.

Carbonate (CO3) reacts with the hydrogen ions and neutralizes the active acidity by changing it to water and carbon dioxide. Placement of lime is critical for the rate of speed and effectiveness of changing the soil pH. Lime works best when it is incorporated into the soil, so that it is distributed evenly throughout the soil profile. In addition, incorporation will place lime in direct contact with soil moisture, which is needed for activation. Under normal climate conditions it take an average time of 12 to 18 months before the benefits of liming can be observed after incorporation. If a perennial crop is established, such as alfalfa or bermudagrass, small amounts of lime can be applied to the soil surface over time. Rainfall will be the source of incorporation under these conditions.

There are several liming sources on the market. Some are more cost effective than others. Quarry Ag lime has traditionally been the most effective and economical source. Several factors should be evaluated when choosing a liming agent. The effective calcium carbonate equivalent (ECCE) is the most important factor. Other factors include the transportation cost from the quarry to the field and the cost of application.

Should you need any assistance in figuring the amount of lime that is needed or calculating the most economical source, I would be more than willing to provide assistance.