Cropside: Staying on top of NPK

AGRONOMIC INFORMATION FROM ONTARIO'S CROP SPECIALISTS

Greg Stewart, Corn Specialist, Ontario Ministry of Agriculture, Food and Rural Affairs

N CALCULATOR RECOMMENDATION for Corn

Factor Input
N Rate
(lb/acre)
Base N Requirement (select soil texture) Loam + 28
Yield Adjustment (enter proven yield) 175 + 135
Heat Unit Adjustment (enter CHU rating) 3000 + 7
Previous Crop Adjustment (enter previous crop) soybeans – 27
Prices: Enter Expected Corn Price ($/bushel) $4.85
Enter Fertilizer Price ($/lb of N) $0.59
Price Ratio Adjustment – 11
Total N Recommendation 132
Enter Starter N 12
Enter Manure N 0
Pre-plant Additional N Recommendation 120
Sidedress Additional N Recommendation 96

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TIP:
You can go to
www.gocorn.net to change the information to match your 2011 corn cropping scenarios.

omafra p recommenation table for corn

Soil Test P
Phosphate (P2O5) Required
(ppm) (kg/ha) (lb/ac)
0 – 3 110 99
4 – 5 100 90
6 – 7 90 81
8 – 9 70  63
10 – 12 50  45
13 – 15  20 18
16 – 20  20 18
21 – 30  20 18
31 – 60  0 0
61 +  0 0

 

 

 

 

 

 

 

 

 

 

 

TIP:
P deficiency is generally associated with early stages of corn growth and it will grow out of the purpling once the root system develops. But, early deficiency may reduce yield and/or delay maturity. Be sure there is enough early season P?available.

omafra k recommendation table for corn

Soil Test K
Potash (K2O) Required
(ppm) (kg/ha) (lb/ac)
0 – 15 170 153
16 – 30 160 144
31 – 45 140 126
46 – 60 110 99
61 – 80 80 72
81 – 100 50 45
101 – 120 30 27
121 – 150 0 0
151 – 250 0 0
251 + 0 0

 

 

 

 

 

 

 

 

 

 

 

tip:
Be aware of K soil tests that have dropped over the last five years. Recent plot work has shown significant yield advantage to corn starter fertilizers that have some K in them, especially when soil tests are below 80 PPM. •

About Greg Stewart 24 Articles

Corn Specialist, Ontario Ministry of Agriculture, Food and Rural Affairs