Placement of P & K on Corn

Jeff McCutcheon, Extension, Agriculture/Natural Resources, Agent
Keith Dennis, Perry County Producer.
Phil Rzewnicki, On Farm Research Coordinator
 

Objective

To compare corn yield under three different fertilizer programs.
 
 
Cooperator: Keith Dennis Soil Test: pH 6.5
County of Site: Perry                P 23 ppm
Nearest Town: Rushville                K 114 ppm
Major Soil Type: Centerberg & Luray               CEC 9 meq/100g
Drainage: Improved  Variety: Seed Consultants 1118
Tillage: Minimum Till Planting Rates: 27,000
Previous Crop: Corn Planting Date: May 11, 2000

Methods

A study was designed to compare corn yield under three different phosphorus and potassium fertilizer programs. Plots were field length (>750 ft.) and 54 ft. wide, replicated six times and completely randomized. 190 lb. actual nitrogen was applied as anhydrous in all three plots. One fertilizer program was 18-46-60 actual applied by broadcasting. The second fertilizer program was 18-46-60 actual applied with the anhydrous and placed about 8 inches in the soil profile. The third program was 9-23-30 actual applied with the anhydrous and placed at the same depth as the second. All fertilizer applications were made on April 27 or 14 days before planting.
 

All plots received a surface tillage pass with an Aerway unit. The shallow tillage probably incorporated the broadcasted fertilizer to a depth of two to three inches. This is the third year for this trial using the same treatment areas as the previous years.

Results
 
Treatment
Average
Yield Bu/Ac1
 Treatment
Cost/Ac.2
Broadcast Full Rate
161.98
$19.04
Full Rate Deep Placement
166.12
$24.40
Half Rate Deep Placement
160.18
  $16.15
                                                       NS3 
1 15% moisture.
2 Includes actual fertilizer cost, plus estimated machinery and fuel cost based on "Ohio Farm Machinery Economic Cost Estimates for 2000."
3 F= .98, CV=4.63%

Summary

Finding no significant differences between the three treatments was not surprising when you consider that the soil test values are above the critical level for both phosphorus and potassium. Past research indicates that if soil test values are above the critical level then specific placement of the fertilizer will have no significant effect on yield. This trial should also be done on a field that has soil test values below the critical level. In that case, past research indicates that fertilizer placement will have a greater effect on yield.