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Keep soil pH in mind when selecting hybrids and fertilizer.

Agronomy Bulletin 121 - MAXIMIZE YIELD IN HIGH pH SOILS

Influence of soil pH on plant nutrient availability

Situation

Corn hybrid selection and fertility planning are key in alkaline, or high pH, soils. High-pH soils reduce the availability of plant nutrients, including zinc, iron and phosphorus. Interveinal yellow stripes on middle to upper leaves are signs of iron deficiency, while white stripes on young leaves are characteristic of zinc deficiency. Dark green or purple coloring of lower leaves indicates phosphorus deficiencies.

Factors to Consider

  • Hybrid performance in high-pH conditions
  • Field soil types and textures
  • Soil sampling
  • Organic matter

Action Plan

  1. UNDERSTAND HIGH-pH SOILS. Soil pH is a measure of the relative acidity or alkalinity of the soil solution. Soil acidity increases as pH drops below 7.0; soil alkalinity increases as pH increases above 7.0. Soil pH is expressed on a 14-point scale where 7.0 is considered neutral.
  2. CHOOSE HYBRIDS FOR HIGH-pH SOILS. With the genetic advances of today’s hybrids, it’s possible to raise a viable crop in high-pH soils. For instance, Mycogen Seeds rates hybrids for visual interveinal chlorosis and yield potential, among other key crop characteristics. When planting into high-pH soils, growers should select a hybrid with the right combination of visual chlorosis rating score and above-average yield potential under these conditions. Your local Mycogen Seeds commercial agronomist can help with hybrid selection.
  3. COLLECT SOIL SAMPLES. Soil sampling is the most proactive way to determine how to best manage a field’s nutrients. After harvest, sample the top 6 to 12 inches of soil and send to a professional soil laboratory for a complete analysis. Collect samples, at minimum, every two years. Read more about soil sampling here.
  4. APPLY THE RIGHT NUTRIENTS IN THE CORRECT LOCATION. When dealing with high-pH soils, it’s important to manage plant nutrients to maximize yield. High-pH soils require higher levels of zinc, sulfur, iron and phosphorus. Follow the soil lab’s recommendation for your yield goal and gather input from your trusted agronomist. For a healthy crop, combine zinc, iron, sulfur and some phosphorus in a starter fertilizer blend during planting. The sulfur will amend the soil and lower pH in the root zone, making the zinc, iron and phosphorus more available to the corn plant.
  5. CORRECT EXCESS ALKALINITY. Elemental sulfur combines with oxygen and water to form sulfuric acid, lowering the pH. Applying elemental sulfur to acidify alkaline soil to a desirable pH range requires large quantities of sulfur due to the buffering capacity of high-pH soils. This is generally not a recommended practice, and the economics should be carefully evaluated before considering this option.

Summary

Proper nutrients paired with the right hybrids are critical to reaching full yield potential in high-pH soils. For more information, contact your local Mycogen Seeds commercial agronomist or trusted agronomic adviser.

Resources

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Published on Friday, July 22, 2016