Safe rates of liquid starter for corn

Submitted by John Heard, MAFRD Soil Fertility Specialist

Safe rates of liquid starter for corn

Phosphorus availability is very important for the corn plant when seeding early in cool soils. But when those soils are dry, the risk of seedling toxicity increases when fertilizer is placed in the seed furrow. Using the South Dakota State University calculator http://www.ipni.net/article/IPNI-3268 , here are the estimated rates of 10-34-0 that would lead to a possible 5% stand reduction under various soil and moisture conditions.

Rate of fertilizer (10-34-0) estimated to cause 5% stand reduction in 30” row corn.

Soil moisture at seeding Fine-medium texture

(clay and loam)

Coarse texture

(sand)

Dry 23 lb P2O5 (5.8 gpa) 18 lb P2O5 (4.7 gpa)
Borderline 31 lb P2O5 (7.8 gpa) 23 lb P2O5 (5.8 gpa)
Moist 46 lb P2O5 (11.6 gpa) 31 lb P2O5 (7.8 gpa)

 

This calculator can be used to assess other fertilizers, seeding configurations, etc.

Note – the removal of phosphate by corn is about 45 lb P2O5 per bushel. So unless yield expectation is low, other placement methods are usually needed to make up this difference on soils testing medium or less in P.

 

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