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Optimal Utilization of Phosphorus, Potassium and Sulfur Fertilization in Corn-Soybean Rotations

Start Date: 2011
Principal Investigator: Daniel Kaiser
Organization: University of Minnesota, Department of Soil, Water, and Climate
Status: Complete

Background Info

Making sure appropriate nutrients are applied in cropping rotations is key to maximizing both yield and profit potential. Past research has shown yield benefits for phosphorus (P), potassium (K) and sulfur (S) applied to corn and potentially to soybeans. This study examines the effect of the application of these nutrients on corn and the following soybean crop to determine if higher nutrient levels and specific combinations of nutrients are necessary to obtain optimum yields.


Examine the effects of K rates applied before corn with and without P or S, on grain and stover quality and yield

Determine if K nutrition differs when either P or S is applied to corn

Examine interactions between P, K, and S when applied in combination by measuring the uptake of macro- and micronutrients and their relationship with corn grain yield

Determine the impact of previous nutrient applications and varying concentrations of K in soils on soybean growth, nutrient uptake, yield, and grain quality following one cropping year of corn

Examine impacts of fertilization on sub-soil P and K levels over long-term corn-soybean rotations

Study how sulfur cycles within a corn-soybean rotation

Evaluate the effect of multiple nutrient deficiencies on remote sensing data as multi-spectral cameras or ground based active sensors (crop circle)

Study the impact of P, K, and S fertilization on soil test K measured on air dried and field moist samples

Key Findings

Corn plants tended to take up more K than was needed from the high application rate, and most of that uptake was in the plant stover at the end of the season. Uptake in the stover provides a source of K that could be available to the following soybean crop.

There was no consistent evidence in the first year of the study of an interaction between P, K or S on yield of corn.

Studying the second-year soybeans showed no clear effect of the previous fertilizer applications on yield, but differences could be seen in soybean grain protein, oil and amino acid concentrations.

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