2018 Corn Product Response to High pH Soils – DEKALB

Trial Objective:

  • High pH soil is generally classified as having a soil pH of 7.6 or higher and may be caused by several different factors including excess lime, high soluble salt concentration, and high nitrate-nitrogen concentration.
  • In Western Kansas and Eastern Colorado, excess lime from high calcium carbonate concentrations in the soil parent material is the source of high pH soils, which are found on eroded hillsides and cut areas in fields.
  • Corn seed products often respond differently to high pH soils with some being susceptible, some moderately tolerant, and others tolerant.
  • Crops growing in high pH soils may express iron deficiency chlorosis (IDC). IDC symptoms include an overall paleyellow color, leaf interveinal chlorosis, stunted growth, and the inability to uptake key nutrients, which are tied up in high pH soils.
  • Better product characterization for tolerance to high pH soils allows for improved product placement to maximize yield potential.
  • The objective of this study was to evaluate visual growth and yield responses of DEKALB® brand blend products in moderate pH soils and high pH soils.

Research Site Details

  • Ten DEKALB® corn brand blend products were planted in two separate soil pH blocks in the same field. An additional 70 different commercial and experimental corn products were also planted in each soil pH block. All products were grouped into the following relative maturity (RM) categories shown in Table 1. Average product yields were compared to the average yield of all similar relative maturity products in each soil pH block.
  • The soil pH for the moderate pH block ranged from 7.3 to 7.6, while the high pH block ranged from 7.9 to 8.6. Soil pH was determined by collecting 28 soil samples in a grid pattern for each soil pH block.
  • Each block contained two replications of all corn products. 
  • A visual color rating was taken at the V8 (8 visible leaf collars) and VT (tasseling) growth stages. The color scale ranged from a very dark green, which was rated 2, to a pale-yellow color, which was rated 8. These ratings were then broken into three separate seed product placement recommendations: Highly Recommended, Recommended in Most Situations, and Not Recommended for high pH soil field conditions.







  • None of the products exhibited visual differences in soil pH tolerance when planted in moderate pH soil conditions (data not shown).
  • In high pH soils, DKC51-91RIB, DKC54-74RIB, and DKC58-34RIB brand blends all had a dark green, healthy plant color at V8 and VT growth stages and yielded above similar relative maturity products. These products are highly recommended on high pH soils.
  • In high pH soils, DKC55-84RIB and DKC57-97RIB brand blends had a slightly less than desired visual appearance throughout the growing season but yielded above or near similar maturity products. These products are recommended for most situations on high pH soils.n high pH soils, DKC51-91RIB, DKC54-74RIB, and DKC58-34RIB brand blends all had a dark green, healthy plant color at V8 and VT growth stages and yielded above similar relative maturity products. These products are highly recommended on high pH soils.n high pH soils, DKC51-91RIB, DKC54-74RIB, and DKC58-34RIB brand blends all had a dark green, healthy plant color at V8 and VT growth stages and yielded above similar relative maturity products. These products are highly recommended on high pH soils.
  • In high pH soils, DKC55-84RIB and DKC57-97RIB brand blends had a slightly less than desired visual appearance throughout the growing season but yielded above or near similar maturity products. These products are recommended for most situations on high pH soils.n high pH soils, DKC51-91RIB, DKC54-74RIB, and DKC58-34RIB brand blends all had a dark green, healthy plant color at V8 and VT growth stages and yielded above similar relative maturity products. These products are highly recommended on high pH soils.
  • In high pH soils, DKC55-84RIB and DKC57-97RIB brand blends had a slightly less than desired visual appearance throughout the growing season but yielded above or near similar maturity products. These products are recommended for most situations on high pH soils.
  • DKC55-53RIB and DKC56-45RIB brand blends had moderate visual appearances at the V8 and VT growth stages but, when compared against similar relative maturity corn products, yielded below average on high pH soils but yielded above average when planted on near moderate pH soils. These products are recommended in most situations on high pH soils.
  • DKC64-25RIB brand blend has average tolerance to high pH soils and is positioned for lower-yielding soil types and environments.
  • DKC61-98RIB and DKC63-57RIB brand blends had below average visual ratings during the season and yielded below similar relative maturity corn products in the high soil pH block. The products are not recommended on high pH soils.

What Does This Mean for Your Farm?

  • High pH soils are typically found in areas with eroded top soil and topography changes that make it difficult to achieve a direct yield comparison of how various seed products perform under high pH soils versus moderate pH soil conditions. Producers may want to keep this in mind when making product comparisons on their farm.
  • The importance of selecting a corn product that can tolerate high pH soil conditions can vary due to the proportion of acres in each field that have high pH soils. For example, in a field that is primarily comprised of high pH soils, selection of an IDC tolerant product will be key, whereas in a field comprised of only 1% high pH soils, seed product selection for IDC tolerance is less important.
  • Assessing a corn product’s high pH soil tolerance by a visual color rating is impacted by soil pH, but can also be influenced by other factors such as soil temperature, nutrient availability, and nutrient uptake. Producers should assess all potential causes when evaluating product performance under high pH soil conditions.
  • Farmers should work closely with their local sales team when selecting products to plant in high pH soil conditions.