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Fertilizer Use Efficiency: the North American Experience

Fertilizer Use Efficiency: the North American Experience. IFA Agriculture Committee Fertilizer Demand Meeting Philadelphia, PA May 26, 2003. David W. Dibb, Paul E. Fixen, and Mark D. Stauffer. Potash & Phosphate Institute/Potash & Phosphate Institute of Canada.

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Fertilizer Use Efficiency: the North American Experience

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  1. Fertilizer Use Efficiency:the North American Experience IFA Agriculture Committee Fertilizer Demand Meeting Philadelphia, PA May 26, 2003 David W. Dibb, Paul E. Fixen, and Mark D. Stauffer Potash & Phosphate Institute/Potash & Phosphate Institute of Canada

  2. Fertilizer Use Efficiency:An Old Topic but With New Importance • International Nitrogen Initiative (INI) • Goal: to optimize N’s beneficial role in sustainable food production and minimize N’s negative effects on human health and the environment resulting from food and energy production. • Will focus attention on improving fertilizer N efficiency at a global scale • Multiple Level Nutrient Management • NRCS program under development to subsidize farmer practices that improve nutrient use efficiency • Will test our collective understanding of nutrient use efficiency for N and P

  3. Traditional Nutrient Efficiency Terms • Recovery efficiency (RE) = Increase in uptake per unit nutrient added usually expressed as % • Agronomic efficiency (AE) = Crop yield increase per unit nutrient added such as bu/lb or kg grain/kg nutrient

  4. Agronomic efficiency of fertilizer N used on corn grain in the U.S., 1964-2002 59 43 39% increase in N efficiency 12% increase in fertilizer N per ha 40% increase in corn yields Since 1975:

  5. N fertilizer recovery efficiency using on-farm measurementsOpportunity for improvement Cassman et al., 2002

  6. Areas of opportunity for improvement in fertilizer N efficiency • Continued improvement in cropping system management • Realistic estimation of attainable yield • Yield potential protection – pest management and other cultural practices • Balanced nutrition

  7. Balanced nutrition in the U.S. • Ohio State University – dryland corn • 80 ppm soil test K 45% N recovery • 139 ppm soil test K 80% N recovery • Kansas State University – irrigated corn • No P applied 35% N recovery • 45 kg ha-1 75% N recovery

  8. Balanced nutrition in China

  9. Areas of opportunity for improvement in fertilizer N efficiency • Continued improvement in cropping system management • Use of site-specific precision ag technologies

  10. Site Specific Management:Accounting for spatial variability

  11. Year 3Variable N rate 11.3 t/ha average yield 28-39 39-50 50-62 62-73 Spatial variability in fertilizer N efficiency Year 1Uniform N rate 11.1 t/ha average yield Soybeans In year 2 Indiana; two N rates based on soil type N Efficiency,kg grain/kg N Murrell and Murrell, 2002

  12. Whole field year 1, 47 kg grain/kg N Variable rate year 3, 53 kg grain/kg N Variable N rate contributed to increased N efficiency 40 ha field divided into 10 zones 9 8 8 7 13% increase in fertilizer N efficiency 6 5 Frequency of zones 4 4 3 2 2 2 2 1 1 1 0 0 28-39 39-50 50-62 62-73 N use efficiency, kg grain/kg applied N Murrell and Murrell, 2002

  13. Areas of opportunity for improvement in fertilizer N efficiency • Continued improvement in cropping system management • Use of site-specific precision ag technologies • Better prediction of soil N mineralization • Improved timing of N application • Improved manure management and crediting • Improved fertilizers • Biotechnology?

  14. Is the concept of fertilizer use efficiency the same for P and K as it is with N?

  15. 120 * 100 80 ** P use efficiency, kg corn/kg P 60 40 20 ** * 0 5 10 15 20 25 Bray P-1, ppm Low High The result of applying the definition of agronomic efficiency for N to P • The highest “efficiency” occurs when inadequate amounts are applied at low soil test levels • Building soil test levels to optimum reduces “efficiency” • “Efficient” P use means reduced profitability, water use efficiency, N use efficiency, and land use efficiency

  16. We need to view P and K efficiency as different than N efficiency • A.E. Johnston and P Poulton “The difference method (RE) is appropriate for N … but is less useful for P and K where plant available reserves of these nutrients can accumulate in the soil from past applications of fertilizer.” • Sustainable efficiency (for P&K) – Nutrient input needed to sustain the system at optimum productivity expressed as a removal to use ratio

  17. P and K Sustainable Efficiency in N. America • Review current crop removal to use ratios • Review current soil test levels • Combine the two to assess efficiency • Information Sources: • Soil Test Levels in North America, PPI/PPIC/FAR Technical Bulletin 2001-1. • Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR Technical Bulletin 2002-1.

  18. Partial K budgets for the U.S. (average of 1998-2000) * USDA-NRCS, 2000; Due to manure distribution problems relative to crop demand, this likely overestimates the agronomic contribution.

  19. BC AB MB SK ON PQ PEI WA NB ME MT ND NS R/(F+M) MN OR VT 0.00-0.89 NH ID NY WI 0.90-1.09 SD MI MA 1.10-1.49 CT WY RI IA 1.50-4.99 PA NE OH NJ NV IL IN > 5.00 MD UT DE WV CO VA MO CA KS KY NC TN OK AZ NM AR SC MS AL GA TX LA FL Ratio of K removal by crops to fertilizer applied plus recoverable manure

  20. Percent of Soils Testing Medium or Lower in K in 2001 North America 43%

  21. Partial P budgets for the U.S. (average of 1998-2000) *USDA-NRCS, 2000; Due to manure distribution problems relative to crop demand and unavailability of a portion of manure P, this likely overestimates the agronomic contribution.

  22. BC AB MB SK ON PQ PEI WA NB ME MT ND R/(F+M) NS MN OR VT 0.00-0.49 ID NH NY WI 0.50-0.89 SD MI MA 0.90-1.09 CT WY RI IA 1.10-1.49 PA NE OH NJ NV IL IN >1.50 MD UT DE WV CO VA MO CA KS KY NC TN OK AZ NM AR SC MS AL GA TX LA FL Ratio of P removal by crops to fertilizer applied plus recoverable manure

  23. Percent of Soils Testing Medium or Lower in P in 2001 North America 47%

  24. Viewing removal to use in light of soil test levels • Large regional differences exist across North America in both current removal to use ratios and soil test levels • “1” is often not the appropriate removal to use ratio target for a state or for a field • Soil test levels < optimum: ratio should be < 1 • Soil test levels > optimum: ratio should probably be > 1 • Starter fertilizer needs are often independent of soil test levels or removal to use ratios

  25. SD High but decreasing Low and decreasing IA WI AR GA High and increasing Low and increasing State level P assessment: R/(F+M) 1.8 1.6 1.4 1.2 1.0 Est. crop removal / (fertilizer + manure use) 0.8 0.6 0.4 0.2 0.0 -15 -10 -5 0 5 10 15 20 25 State median soil test level - target level, ppm Target level = lower end of high category

  26. Estimating target removal/use ratio for a field • Target K test = 150 ppm Current test = 130 • Build: (150 - 130) x 9 kg K2O/ppm = 180 kg K2O/ha • To spread build over 4 yrs = 180/4 = 45 kg K2O/ha • Avg crop removal per year = 67 kg K2O/ha • Total to apply = 45 + 67 = 112 kg K2O/ha Target removal to use ratio = 67/112 = 0.60

  27. Examples of apparent recovery efficiency of P fertilizer in long term studies GH = Green house; F = Field. Fixen, 1992

  28. If a field is at its optimum soil test level, and replacement of the P and K removed by crops maintains that optimum level, what is the efficiency of P or K? 100% If use must exceed removal to maintain optimum productivity, soil erosion or fixation are often the cause: • Reduce erosion losses • Utilize banding and annual fertilizer application

  29. Impact of Improving Efficiency on Fertilizer Demand • Critical to properly define efficiency for the nutrient in question • Nitrogen • Good progress has been made in improving agronomic efficiency • Will be significant pressure to further improve agronomic efficiency without sacrificing yield potential • Research shows there is room for improvement • Yields will likely continue to increase faster than N use

  30. Impact of Improving Efficiency on Fertilizer Demand (continued) • Phosphorus and potassium • Will be increasing pressure to improve system efficiency by reducing P levels where excessive • Sustainable efficiency will translate into increased P and K demand in some major production regions • Pressure to improve N efficiency should result in increased support for balanced nutrition with P and K • Higher future crop yields could require higher target soil test levels and temporarily impact demand • The thermodynamic need to replace P and K removal at some soil level sets a lower limit for P and K use • As food needs increase … fundamentals of natural systems indicate a permanent and expanding role for fertilizers in food production

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