increased, while profit and MEY decreased. Profit also decreased

as N rate decreased. Zero profit occurred with 120 lb of N/A and

a fixed cost of $200/A. However, a net loss of $58/A was the

result of zero N rate and $200/A fixed cost. The break even corn

price with zero N and $200/A fixed cost is $2.82/bu or the fixed

cost would have to be reduced to $142/A in order to break even with

zero N at $2.00/bu. Fixed costs can vary between locations due to

pest control and land cost differences. A higher N rate was

required to break even with a $300/A fixed cost than with a $200/A

fixed cost (198 vs. 120 lb/A). The influence of corn price on

profit and MEY of irrigated corn is shown in table 2. At $3.00/bu

MEY is equal to maximum yield which requires about 270 lb N/A.

However, further increases in corn price do not justify additional

production inputs because maximum yield has occurred and additional

inputs only decrease profit.


Table 1. Influence of N cost on MEY and net profit for corn
 production at two levels of fixed input costs.
 Calculations are based on functions shown in figure 1.
 Corn price is $2.00 per bushel.


N Rate Cost of N Cost/price MEYt Fixed Input Costs
lb/acre $/lb ratio bu/acre $200/acre $300/acre

 ---profit $/acre---

 261 0.25 0.13 242 218.75 118.75
 232 0.50 0.25 237 158.00 58.00
 199 0.75 0.38 226 102.75 2.75
 169 1.00 0.50 213 57.00 43.00
 107 1.50 0.75 174 -12.50 -112.50
 45 2.00 1.00 120 -50.00 -159.00

 tUnder certain cost structures MEY represents the minimum loss.
iProfit = (bu/acre x $/bu) (lb N/acre x $/lb N + other input
 costs).