Research Progress Report 329 March, 1968
Fertilization of Continuous Corn on Crosby Silt Loam Lafayette, Indiana 1963-66
R.K. Stivers, Agronomy Department

Summary
Nitrogen (N) Fertilizer Experiments -Even though 200 pounds per acre of N had been broadcast prior to planting, ten pounds per acre of row N from ammonium sulfate gave a 4 bushel per acre yield increase in 1965 which is significant at the 5 per cent level. The same amount of row N from ammonium nitrate resulted in a 3.8 bushel yield increase which is significant at the 10 per cent level. There was no meaningful yield difference associated with row N fertilizer in either 1963 or in 1966.

Of the five annual rates of broadcast N for corn on this Crosby silt loam the 100 pounds per acre rate was most profitable on this relatively low (75 bushel) yield level. A deficiency of soil moisture limited yields in two of the three years.

Phosphorus (P) and Potassium (K) Fertilizer Experiments - One initial broadcast application of 66 pounds per acre resulted in about the same amount of vegetative growth and yield of corn as an equal amount of P applied in three annual row applications.

Increasing rates of row P up to and including 11 pounds (25 pounds P2O5 per acre)
were profitable where no broadcast P had been applied. Where 66 or more pounds per acre of P had been broadcast, there was no meaningful response to annual row P.

There was neither a height nor a yield increase from either row or broadcast K fertilizer. Had the yield level been higher, this might not have been true.

Soil test values of P and K increased after large broadcast applications. Two pounds per acre of P fertilizer were required to obtain an average net change in soil test values of 1 pound per acre of P one year after the fertilizer was applied. The amount of K fertilizer required to obtain an average net change of 1 pound per acre of K was quite variable.

Procedure
The purpose of this research was to compare rates of nitrogen (N), phosphorus (P), and potassium (K) fertilization of continuous corn on Crosby silt loam.

A field testing very low in both available P (10 pounds per acre) and K (80 pounds per acre) was selected on the farm of E.R. Brown in Tippecanoe County, near Lafayette.

PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana