Evaluation of Corn Yield & Nutrient Composition Response to P & K


  • Assess corn yield response to phosphorus (P) and potassium (K) fertilizer applications.
  • Assess the effect of P and K fertilizer applications on corn plant nutrient concentrations at V4, V10-12, VT-R1 and in the harvested grain.

Leaf yellowing on corn plant.

K-deficient plants exhibit leaf yellowing, beginning at the margins and moving in toward the midrib. Symptoms start at bottom of the plant and progress upward. K deficiency can also result in stunted plants with short internodes.



Study Description

  • Plot Layout: 4-row randomized small plots
  • Replicates: 4
  • Location: Arlington, Wis.
  • Tillage: No-till
  • Treatments:
    • Broadcast in spring of 2012
    • 4 rates of P (0, 30, 60, 90 lbs P2O5/acre) as 0-46-0 at each rate of K (0, 40, 80, 120, 160 lbs K2O/acre) as 0-0-60
    • The same treatments were applied to the same plots in spring 2011 before soybean.
  • Soil Tests:
    • Prior to application in spring 2013
    • Soil test P: 6-13 ppm (v. low and low)
    • Soil test K: 48-67 ppm (v. low)


  • Even though soil test P levels were low, P deficiency symptoms were not apparent and there was no significant corn yield response to applied P.
  • There was a significant yield response to K applied at rates up to 120 lbs K2O/acre.
  • These results suggest that:
    • K is more yield-limiting than P at low soil test levels, or
    • Surface application of P in no-till is not effective at increasing yield, regardless of the rate of P applied.
  • Tissue nutrient concentrations at V4, V10 and R1, as well as grain and silage nutrient composition, are not available at this time.

Table - Effect of No-Till Surace Broadcast P and K Rates on Corn Grain Yield

Research conducted by Carrie Laboski, Associate Professor & Extension Nutrient Management Specialist, University of Wisconsin-Madison, as a part of the Pioneer Crop Management Research Awards (CMRA) Program. This program provides funds for agronomic and precision farming studies by university and USDA cooperators throughout North America. The awards extend for up to 4 years and address crop management information needs of Pioneer agronomists, Pioneer sales professionals and customers.

2013 data are based on average of all comparisons made in one location through November 15, 2013. 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.