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Are We Managing for Higher Yields?

Are We Managing for Higher Yields?. Should We Strive for Higher Yields Symposium American Society of Agronomy Annual Meeting November 11, 2002 Indianapolis, IN Paul Fixen Potash & Phosphate Institute pfixen@ppi-far.org Web: www.ppi-ppic.org. Yield trends in the U.S. Corn

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Are We Managing for Higher Yields?

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  1. Are We Managing for Higher Yields? Should We Strive for Higher Yields Symposium American Society of Agronomy Annual Meeting November 11, 2002 Indianapolis, IN Paul Fixen Potash & Phosphate Institute pfixen@ppi-far.org Web: www.ppi-ppic.org

  2. Yield trends in the U.S. Corn 1.9 bu/A/yr Wheat 0.41 bu/A/yr We are managing for higher yields Alfalfa 52 lb/A/yr Soybeans 0.38 bu/A/yr

  3. Are we managing for attainable yields? • What yields are attainable? • A site-specific question • Highest research yields • Farmer examples – rain fed corn in IA and IL • What management practices were used to get them? • Does not tell us what was required • Does offer research direction • What practices are currently being used?

  4. Top corn yields from researchers in 1982 Dr. Roy Flannery New Jersey 338 bu/A Dr. Sterling Olsen Colorado 332 bu/A

  5. Exploitable yield potential in corn H. Warsaw Saybrook, IL F. Childs Manchester, IA 1992-2001 20.1 bu/A/yr 1965-1991 2.0 bu/A/yr IA Contest Winners A yield gap does exist IA State Average 1.6 bu/A/yr

  6. Herman Warsaw yield history, 1966-1985 Saybrook, IL 7.4 bu/A/yr

  7. Rain fed corn yields & rainfall - Herman Warsaw Saybrook, IL 15-year average 274 bu/A Variable rainfall

  8. From Saybrook, IL to Manchester, IA: Climate Growing season climate, 1971-2000 PrecipTempGDD Month Man Urbana Man Urbana Man Urbana Inches F Base 50 Apr 3.3 3.7 47 51 162 212 May 3.9 4.8 59 62 367 436 Jun 4.6 4.2 68 72 557 641 Jul 4.4 4.7 72 75 672 751 Aug 5.0 4.4 70 73 611 702 Sep 3.3 3.2 61 66 412 505 Oct 2.6 2.8 50 54 199 266 Tot/Avg 27.0 27.7 61 65 2980 3513 Source: Midwest Regional Climate Center Manchester, IA Saybrook, IL

  9. From Saybrook, IL to Manchester, IA: Soils Property Childs Warsaw Soil type Kenyon loam Parr silt loam Taxonomy Typic Hapludolls Oxyaquic Argiudolls Cap. Class IIe Org. mat., % 5.5-6.0 5.3 pH 5.3-6.1 6.0 P1, ppm 126 (VH) 81 (VH) K, ppm 374 (VH) 400 (VH) Source: Childs data – Murrell and Childs, 2000; Smith, 2000; Dobermann, 2002 Warsaw data – PPI, 1986. Manchester, IA Saybrook, IL

  10. From Saybrook, IL to Manchester, IA: Soil OM Depth, In Childs Warsaw-light Warsaw-dark Organic matter, % 0-6 5.6 5.8 4.5 6-12 4.5 4.9 3.9 12-18 3.0 3.2 4.3 18-24 --- 1.4 4.3 24-30 --- 0.8 3.8 30-36 --- 0.6 3.6 Source: Childs data – Dobermann, 2002. Warsaw data – PPI, 1977. Fence row 5.2 3.7 2.7 2.3 1.5 0.9 Manchester, IA Saybrook, IL

  11. From Saybrook, IL to Manchester, IA: Farmer attributes Manchester, IA • Dedicated to a concept … but very patient • Warsaw: 20 years of intensively managed continuous corn • Childs: 35 yearsof intensively managed continuous corn Saybrook, IL

  12. From Saybrook, IL to Manchester, IA: Practices Manchester, IA Practice Childs Warsaw Fall tillage Mini MP 14” deep CH 14” deep Hybrid Pioneer 34M95 FS 854 Harv. Population 34,000 - 40,000 36,000 Row spacing 30” 28” Manure Historical high rates 20 T/A annually Fall P2O5+K2O180+120 (99, not 01) 250+250 Fall N, lb/A 50(UAN) 45(DAP) Preplant N 250(NH3 + sep. stab.) 300(UAN)+ 100(AS) Starter, N+P2O5+K2O6+15+15 26+26+26 Postplant N 50(UAN) 75(UR) 3.5-4’ tall N 50(UAN+Guardian) None Fert N, lb/A 406 (1.0 bu/lb) 546 (0.7 bu/lb) Other nutrients Boron Sulfur Saybrook, IL

  13. Corn grain produced in the U.S. per unit of fertilizer N used, 1964-2000. 1.03

  14. Questions about requirements: Which practices are critical and at what level? • Determination of site-specific attainable yield estimates (Crop models) • Carbon cycling – crop and environmental impacts • Crop rotation vs monoculture • Tillage requirements … no till/strip till • Minimum N requirements, NH4+ vs NO3-, timing • Role of subsoil fertility, organic matter, etc. • Role of manure application • Minimum soil test P and K requirements • Role of secondary and micronutrients • Importance of starter fertilizer (early yield components)

  15. Early Plant P status Impacts corn yield potential (outdoor hydroponics study) • P concentrations below 0.5% prior to V3-V4 (ISU System), reduced kernels initiated per ear and grain yield • If kernel abortion is limited, final kernel number should be correlated with kernels initiated • High early plant P concentrations should be important for conserving yield potential in high yielding environments Barry & Miller, 1989

  16. P uptake per unit of root length (Barber, Purdue). Seed is dominant P source V2 - Soil becomes dominant P source Plant demand on the soil for P approaches a maximum

  17. Plant P concentrations in Herman Warsaw’s corn(Field 3W) Sampled by Shields Soil Service, Saybrook, IL; Analysis by Agrico Labs. • Theory (Barry and Miller; Barber) and practice (Warsaw) suggest starter P might be important to obtain sufficient early plant P concentrations. • Has not been demonstrated as essential for reaching attainable yields underactual field conditions.

  18. Soil Test P and K requirements for very high yields: Classical theory • For soil immobile nutrients like P or K, the STL vs % yield relationship should not vary with site yield potential unless plant population increases enough for adjacent roots to compete for each other for P and K (Bray, 1954; Bray, 1963). • Roots normally occupy less than 1% of soil volume (Barber, 1984) … an increase in size of the root system translates into a greater volume of soil P or K being available for uptake. • As long as the size of the root system increases proportionally with yield, a higher yielding crop should not need a higher P or K concentration at the root surface … should not require a higher soil test level.

  19. Soil Test P and K requirements for very high yields: Conditions that could lead to higher requirements • Shoot growth increases that exceed root growth increases as yields climb • increasing N, P or available water (Barber, 1984) • decreasing light intensity (Troughton, 1980; Horvath et al., 1980) • soil temperatures in the 75-85 F range (Walker, 1969; Nye and Tinker, 1977) • Redistribution of roots from the surface soil to a low P or K subsoil • soil factors (organic matter, pH, structure, etc.) • varietal factors – vertical vs lateral rooting tendencies • Each % increase in yield has greater economic value … want to be further up the response curve

  20. Repeated applications of P or K build profile soil test levels • Manure applied for 10 years in this example • The higher the surface levels, the greater the depth of high fertility • A role that manure has played in high yield systems? • If depth is critical, deep placement may be an alternative to extreme surface level (Ongoing Purdue study) Data: Sharpley et al., 1984

  21. Research needed • “Research has given us good components or parts … But greater strides toward high yields will likely come through fitting those parts into combinations that produce positive interactions.” Dr. Robert Wagner, 1979

  22. Impact of hybrid on the influence of N rate on yield response to plant population in Colorado 27K vs 38K 39K vs 46K S.R. Olsen, reported by W. M. Stewart, 2000

  23. Soil test P levels in the 6 leading corn states, 2001 Percent under 20 ppm Bray P1 equivalent Indiana 25 Ohio 31 Illinois 16 Iowa 39 Minnesota 60 Nebraska 47

  24. Soil test K levels in the 6 leading corn states, 2001 Percent under 160 ppm K Indiana 71 Ohio 56 Iowa 54 Illinois 56 Nebraska 12 Minnesota 51

  25. Phosphorus and potassium crop removal to nutrient use ratios for the 6 leading corn producing states. Medium or below in K: OH IN IL PPI, 2002. Average of 1998-2000.

  26. Are we managing for attainable yields? • Probably not since typical yields are below what is likely attainable • To narrow the gap we need expanded research at high yield levels • Define site-specific attainable yields • Management practices essential to attain them • A mix of small plot multi-factor research and on-farm field scale studies … linked with appropriate models • Modern technologies should facilitate narrowing the gap between attainable and typical yields • “Calibrated” simulation models to help define attainable yields • Improved weather data and management tools • Site-specific technologies for greater efficiency • Biotechnology for yield protection … and building

  27. Are We Managing for Higher Yields? Should We Strive for Higher Yields Symposium American Society of Agronomy Annual Meeting November 11, 2002 Indianapolis, IN Paul Fixen Potash & Phosphate Institute pfixen@ppi-far.org Web: www.ppi-ppic.org

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