Yield Models Implied by Traditional Fertilizer Recommendations and a Framework for Including Nontraditional Information
Terry L. Kastens*,a,
John P. Schmidtb and
Kevin C. Dhuyvetterc
a 304F Waters Hall, Dep. of Agricultural Economics, Kansas State University, Manhattan, KS 66506
b 2004 Throckmorton Plant Sciences Center, Dep. of Agronomy, Kansas State University, Manhattan, KS 66506
c 306B Waters Hall, Dep. of Agricultural Economics, Kansas State University, Manhattan, KS 66506
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Fig. 1. Fertilizer N recommendation from four laboratories as a function of soil test N. The yield goal was 2.83 Mg ha-1 (42 bu acre-1).
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Fig. 2. Fertilizer P recommendation from four laboratories as a function of soil test P. The yield goal was 2.83 Mg ha-1 (42 bu acre-1).
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Fig. 3. Fertilizer N recommendation as a function of soil test N for Kansas State University (KSU) Laboratory and KSU-based Model. Soil test P was fixed at 16 mg kg-1; fertilizer P was optimized; yield goal was fixed at 2.83 Mg ha-1 (42 bu acre-1); AZ simulation term was fixed at its mean.
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Fig. 4. Fertilizer P recommendation as a function of soil test P for Kansas State University (KSU) laboratory and KSU-based Model. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N was optimized;yield goal was fixed at 2.83 Mg ha-1 (42 bu acre-1); AZ simulation term was fixed at its mean.
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Fig. 5. Predicted wheat yield response to fertilizer P at different levels of soil test P (mg kg-1) for the Kansas State University-based Yield Model. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N was optimized; AZ simulation term was fixed at its mean.
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Fig. 6. Optimal fertilizer P as a function of time for the four lab-based models. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N and fertilizer P were optimized annually; initial soil test P was 5 mg kg-1; AZ simulation term was fixed at its mean.
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Fig. 7. Soil test P as a function of time for the four lab-based models. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N and P were optimized annually; initial soil test P was 5 mg kg-1; AZ simulation term was fixed at its mean.
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Fig. 8. Profit (crop revenue less fertilizer cost) as a function of time for the four lab-based models. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N and P were optimized annually; initial soil test P was 5 mg kg-1; AZ simulation term was fixed at its mean.
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Fig. 9. Annually amortized profit (crop revenue less fertilizer cost) as a function of time for the four lab-based models if following the program for the number of years shown on the x-axis. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N and P were optimized annually; initial soil test P was 5 mg kg-1; AZ simulation term was fixed at its mean.
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Fig. 10. Optimal fertilizer P as a function of time for the Olsen's Agriculture Laboratory-based Model, based on a 1-yr and a 10-yr time horizon. Soil test N was fixed at 45 kg ha-1 (40 lb acre-1); fertilizer N was optimized annually; initial soil test P was 5 mg kg-1; AZ simulation term was fixed at its mean.
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Copyright © 2003 by the Soil Science Society of America.
