Soil Test Phosphorus and Potassium Levels in the Corn Belt
Background and Objectives
- Balanced soil fertility management is critical for achieving crop genetic yield potential and maximizing profitability.
- Recent evidence suggests that P and K fertilizer rates in some areas may not be keeping pace with increasing crop yields that are accompanied by higher nutrient removal.
- The objective of this study was to assess soil fertility levels in Pioneer GrowingPoint Agronomy on-farm corn research trials and fields enrolled in EncircaSM Yield services in the Corn Belt.
- DuPont Pioneer agronomists and Encirca certified services agents collected soil samples from 8,925 fields in 12 Corn Belt states between fall 2015 and spring 2016.
- Soil samples were submitted to Waypoint Analytical for P and K analysis and test results were compared to University fertility recommendations to determine the percent of samples that fell below state optimum levels.
Phosphorus Deficient Soils
Figure 2. Percent of soil samples that fell below state optimum levels for P in the Corn Belt.
- Phosphorus deficiency was prevalent throughout the Corn Belt, with the greatest frequency of deficient soils observed in western Corn Belt states.
Potassium Deficient Soils
Figure 3. Percent of soil samples that fell below state optimum levels for K in the Corn Belt.
- Potassium deficiency was most frequently observed in the central Corn Belt and Michigan. Note that university-recommended optimum K levels are significantly higher in Iowa compared to other states in the region.
Authors: Marissah Schulte and Andy Heggenstaller
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Results are based on observations made at 8,925 locations through June 30, 2016. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary.