Corn products often respond differently to high pH soils with some being susceptible, some semi-tolerant, and others tolerant in how they respond both in terms of yield and visual appearance. Hybrids that are susceptible usually express iron deficiency chlorosis (IDC) with symptoms including yellow leaves, interveinal chlorosis, and stunted growth.
Key nutrients, including iron, phosphorus, copper, and zinc are tied up in high pH soils.1 A high soil pH for corn is generally classified as having a soil pH of 7.6 or higher and can be caused from either excess calcium carbonate, excess lime, high soluble salt concentration, and/or high nitrate-nitrogen concentration.2 In Western Kansas and Eastern Colorado, excess lime from high calcium carbonate concentrations in the soil parent material is the source of the high pH, which can be found on eroded sidehills and cut areas in fields.
Better product characterization of response to soil pH allows for better product placement to maximize yield potential.
The objective of this study was to determine the visual and yield response of corn products to moderate (6.7 to 7.5) and high (7.6+) pH soils.
RESEARCH SITE DETAILS:
|Location||Burlington, CO||Soil pH Range||6.7 to 8.1|
|Soil Type||Silt Loam||Harvest Date||10/21/19
|Tillage Type||Strip tillage||Seeding Rate
- For this trial, a total of 75 different commercial and experimental corn products of varying relative maturities (RMs) were each planted in two separate pH blocks in the same field (See Table 3 for list of additional products). One block has a soil type with a high pH and the other block has a moderate pH:
- 42 products had RMs ranging from 103- to 107-day and were grouped as 105 RM
- 33 products had RMs ranging from 108- to 113-day and were grouped as 110 RM
Ten of these products were DEKALB® brand blend corn products; only the results of the DEKALB products are shown in this report.
- A visual color rating of the foliage was taken at the V8 and VT growth stage:
- very dark green = 2
- pale-yellow color = 8
For each pH block, the average yield of each individual product was compared to the average yield of all the products within the RM group. This allowed us to better identify those products which performed above average on the high pH soil.
Trial was replicated: 4 replications in the high pH zone and 4 replications in the moderate pH zone at each location.
Soil pH was determined by grid sampling each trial area at a 1/10th acre density.
UNDERSTANDING THE RESULTS
In this trial year, the lower than expected yields are attributed to cold, wet soils early in the growing season followed by extensive wind and heat during grain fill.
Across all products tested, the average yield of the 105 RM group was 0.5 bu/acre greater compared to the average yield of the 110 RM group in the high pH block.
On the moderate pH block, the average yield of the 110 RM group was 8.8 bu/acre greater compared to the average yield of the 105 RM group. In optimal growing conditions, longer RM products generally have greater yield potential.
Visual estimations during vegetative stages closely correlated to the yield results (see Tables 1 and 2).
WHAT DOES THIS MEAN FOR YOUR FARM?
The importance of selecting a product able to tolerate high pH soils varies based on soil pH level and the proportion of high pH soil acres in each field.
High pH soils are typically found in areas with eroded top soil and topography changes, which make it difficult to compare yields between neutral and high pH areas of the field. Producers need to keep this in mind while making yield comparisons on their own farm.
DEKALB® offers corn products for high pH soils, talk with your local seed representative for more information on product placement with your operation.
1 National Soil Survey Center. 1998. Soil quality indicators : pH. United States Department of Agriculture Natural Resources Conservation Service.
2 Ferguson, R.B. 2006. Nutrient management for agronomic crops in Nebraska. EC06-155.