If soil pH is below 5.2, managing soil acidity should have a high priority. Soil acidity prevents development of a strong vigorous root system, that in turn prevents normal wheat growth and development. Consequently, the effectiveness of other inputs vital to efficient and profitable wheat production will be impaired. Frequently, elevated soil test levels of other nutrients will be evident on strongly acidic fields since the uptake, and subsequent removal, of essential nutrients will be much lower.
Soil acidity is easily corrected with liming. However, lime application rates needed to correct the soil pH (increase pH to 6.5-6.8) are often very high. Also, economical sources of lime are often not available in most of the Great Plains. As a general rule, if the soil pH is less than 5.5 and 25 percent of the lime required to bring the pH up to 6.8 is applied (most generally the normal lab recommendation), the resulting soil pH should increase to about 5.5, and little yield loss will occur. Keep in mind, however, at reduced rates lime will need to be applied more frequently. Lime applied at 25 percent of the recommended rate should keep the soil pH high enough to alleviate aluminum toxicity for 2 to 5 years, but fields should be carefully monitored to prevent yield loss. Applying about 50 percent of the lime required to increase soil pH to 6.8 should result in a soil pH of about 6.0.
All liming materials will neutralize soil acidity equally as long as equivalent rates of effective lime are applied. Regardless of the source of lime (dry agricultural, fluid, or commercial pelleted lime), the appropriate rate should be based on the Effective Calcium Carbonate Equivalent (ECCE) content of the lime (also referred to as ECC, ENV, etc.). The ECCE of liming materials vary depending on the composition, fineness of grind, and purity of the material. Purchase decisions should be based on the ECCE value provided by lime vendors. There are no short cuts or miracle liming materials for correcting soil pH. In order to neutralize soil acidity, a given amount of ECCE will be required, regardless of source.
Another practice proven to be helpful in managing soil aluminum toxicity problems are drill-row applications of 30 to 40 pounds of P205 with seed. When soluble phosphate fertilizer is placed with the seed, relatively insoluble aluminum phosphates form, which take the soluble Al out of soil solution in the area of the developing seedling. The seedling root system can then develop normally. Keep in mind, however, the soil acidity has not been neutralized and lime or P fertilizer application will be necessary for the next crop. Drill-row phosphate applications are one year, stop-gap measures when it is not practical to lime before planting.