Formulating Suggestions for Phosphorus and Potassium Use in Agricultural Field Crops
The Tri-State Fertilizer Recommendations framework offers tailored nutrient application guidelines for crops such as corn, soybean, wheat, and alfalfa. This system, which covers parts of Illinois, Indiana, and Ohio, bases its nutrient recommendations primarily on soil test levels and the expected yield response of the specific crop.
Key aspects of the framework include:
- **Soil Test Levels**: Soil P and K levels are measured through standardized soil tests, categorizing soil nutrient availability into levels such as low, medium, or high.
- **Crop Yield Response**: Nutrient recommendations are adjusted according to the likelihood of crop yield increase based on soil nutrient status. For example, soils with low P or K test levels generally require higher fertilizer inputs to realize optimal yield, whereas soils with high nutrient status require little or no additional fertilizer to avoid over-application and environmental risks.
- **Crop-Specific Recommendations**: Each crop has distinct nutrient requirement profiles and uptake patterns. The Tri-State recommendations account for these differences by specifying different P and K rates depending on the crop species and its expected yield goal.
The framework aims to optimize fertilizer use efficiency, enhance crop productivity, and minimize environmental impact. While the exact rates and decision charts are detailed in extension publications from the Tri-State region, the core principle remains consistent: apply fertilizer P and K at rates that reflect soil test status and the economic return from yield increases.
In the example provided, the soil test K for corn is below the "optimal" range of 120-170 ppm, making it "deficient" according to the tri-state recommendations. The potassium recommendation in this case is based on the potassium buildup equation provided in the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa, resulting in a recommendation of 85 pounds of KO per acre.
Similarly, the phosphorus (P) recommendation for a corn yield potential of 150 bushels/acre and a soil test result of 23 ppm is 55 pounds of PO/acre, based on the phosphorus maintenance equation in the same guidelines.
To calculate the amount of fertilizer needed, the first step is to read the fertilizer label and locate the percentage of the target nutrient in the fertilizer source. The framework defines an "optimal" soil test range, "deficient" soil test values, and "sufficient" soil test values higher than the optimal range. If soil test levels for corn P are in the "deficient" categories, extra fertilizer is recommended to build up soil test levels to the optimal range in four applications. The optimal soil test range for corn P is 20-40 ppm.
The tables in the Tri-State Fertilizer Recommendations have a consistent layout that follows the tri-state recommendation framework, with soil test values shown on the left-hand side of the chart. The tables are a quick tool to use in developing P and K recommendations for a variety of row and forage crops, including the tri-state recommendations for corn, soybean, wheat, and alfalfa.
- The Tri-State Fertilizer Recommendations framework, rooted in agriculture science and health-and-wellness, focuses on tailoring nutrient application guidelines for crops like corn, soybean, wheat, and alfalfa, considering both soil test levels and crop yield response.
- To optimize nutrient uptake, the framework factors in not only soil test levels but also the distinct nutrient requirements and uptake patterns of each crop species, which is essential for crop-specific recommendations.
- The application of P and K fertilizers in the Tri-State region is guided by science-based equations, such as the potassium buildup equation for corn, which helps determine the precise amount of fertilizer needed when soil test levels are deficient, aiming for improved nutrition, crop productivity, and environmental sustainability.
