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Illinois Fertilizer Conference Proceedings
January 27-29, 1992

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Table 3: Optimum fertilizer rate for corn yield determined by regressionspacer

  Nitrogen Rate lb/Acre     Coeff. Sig.
Year
Y/T		 Yield ECON QD LN Model Prob. R. Square
63-66 2/4 174 134 * .10 .0001 .5770
67-72 6/6 159 133 .10 .10 .0001 .7390
73-82 4/7 182 151 .10 .10 .0001 .6576
83-87 2/4 164 138 .10 .10 .0001 .7404
  P2O5 Rate #/Acre     Coeff. Sig.
Year
Y/T		 Yield ECON QD LN Model Prob. R. Square
63-66 3/4 118 93 .25 .25 .0001 .6512
67-72 5/6 95 78 .10 .10 .0001 .6053
73-82+ 5/8 90 74 .10 .10 .0001 .6373
73-82- 3/8 68 52 .10 .10 .0001 .3248
83-87+ 2/5 100 76 .25 .10 .0030 .3494
83-87- 2/5 69 51 .25 .25 .0808 .1700
  K2O Rate #/Acre     Coeff. Sig.
Year
Y/T		 Yield ECON QD LN Model Prob. R. Square
63-66 3/4 59 49 * * .0226 .0696
67-72 3/6 76 65 * .10 .0001 .2302
73-82 2/8 117 102 * * .0603 .1878
83-87? 1/4 60 52 .25 .25 .3754 .1507

Y/T = No. Yrs. Combined/No. Yrs. in Group

* = Probability > .25

+ = @ 240 lb N/acre = @ 60 lb N#/acre

? = 1983, Only year w/typical curve

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