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Phosphorus... Essential for Life

Phosphorus... Essential for Life. Dr. Mark D. Stauffer President, Potash & Phosphate Institute of Canada Senior Vice President, Potash & Phosphate Institute. Phosphates are a vital ingredient in the diets of all living things…. P.

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Phosphorus... Essential for Life

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  1. Phosphorus... Essential for Life Dr. Mark D. Stauffer President, Potash & Phosphate Institute of Canada Senior Vice President, Potash & Phosphate Institute

  2. Phosphates are a vital ingredient in the diets of all living things… P • is the second most abundant mineral nutrient in the human body • 80% of P in humans is in bones & teeth accounting for 20% of the mineral ash & 1% of total body weight • The remainder is widely distributed throughout the body, in combination with fats, proteins and salts in every cell

  3. Phosphate chain ATP: Nature’s energy store Phosphorus is of universal importance to every living cell… P is incorporated into… • Nucleic acids (DNA, RNA, genes, chromosomes) • Proteins • Lipids • Sugars • Enzymes • Energy rich P compounds (ATP, ADP)

  4. P is critical to basic plant physiology: • Energy storage & transfer for every biological process • photosynthesis • respiration • cell division, development, enlargement, gene transfer, reproduction “Without phosphorus, there is no cell, no plant, and no grain… Without adequate phosphorus, there is a lot of hunger…”

  5. LOWERS FARMER RISK & RAISES PROFIT POTENTIAL P Impact on crops • Vigorous crop (Shoot/Root) growth • Improved resource utilization • water, nutrients • positive environmental implications • Better resistance to stress • disease, pest, moisture, temperature • Earlier maturity • good grain & fruit development • better crop quality, yield

  6. 30 Grain (Wheat) 25 • the majority of P is removed in fruit/grain 20 Kg P /ha Head 15 Stem Crop Plant part P content, % 10 Corn Grain 0.22 Stover 0.17 Cotton Seed 0.66 Stalks 0.24 Soybeans Grain 0.42 Straw 0.18 Wheat Grain 0.42 Straw 0.12 5 Leaves 0 0 4/19 300 5/10 600 6/03 900 6/19 1200 7/13 1500 7/31 1800 8/13 Growing Degree Units P is mobile in the plant…linked to metabolic processes… & is concentrated in the most active areas of growth (Jacobsen et al. 1992)

  7. Agronomic characteristics of P deficiency … darkened leaves … purpling of leaves / stems

  8. stunted growth • reduced leaf number, • expansion & surface area P deficiency reflected in poor development at all stages…

  9. 14 13 Roots 80 N 12 11 40 N 10 Number of Adventitious Roots and Tillers/Plant 8 9 0 N 7 6 5 Tillers 4 3 2 1 0 45 90 135 180 225 270 315 360 P2O5 Rate, lb/A (Fanning and Goos 1992) P Impact on plant roots & tillers (wheat)

  10. N P2O5 WUE Increase kg/ha kg/cm H2O in WUE, % 0 0 30 --- 0 45 38 27 0 90 40 33 40 0 26 -13 40 45 42 40 40 90 49 63 P Impact on water use efficiency (wheat)

  11. Wheat K uptake, kg/ha 600 64kg P 500 400 16kg P 300 200 0kg P 100 0 0 60 120 180 240 N rate, kg/ha P Impact on nutrient use efficiency (wheat) (Schwartz and Kafkafi)

  12. P Impact on residual soil nitrate & leaching 200 soil profile NO3-N after 30 years… 150 without P with P 100 Soil NO3-N in upper 3 m, kg/ha At optimum N rate P reduced residual nitrate by 66 % 50 0 0 40 80 120 160 200 N rate, kg/ha (Schlegel, Dhuyvetter, and Havlin, 1996)

  13. P Impact on crop maturity (barley) 118 116 114 112 Site 1 Days to Maturity of Barley 110 Site 2 108 106 104 0 13 27 40 P2O5 Rate, kg/ha (Westco – Alberta, Canada)

  14. 30 year average 140 13000 with P 12000 without P 130 11000 120 10000 110 9000 8000 100 7000 Yield, kg/ha 90 Cost of production, $/t 6000 80 5000 4000 70 3000 60 2000 50 1000 40 0 0 22 45 67 90 112 134 157 180 202 224 N rate, kg/ha P Impact on yield & cost of production Schlegel, Dhuyvetter, and Havlin, 1996

  15. How much P is in the soil? • 4 kg P/ha or less is plant-available in soil solution. Soil Solution • An actively growing crop can use up all of the P in soil solution twice a day. • A soil’s ability to maintain a plant-available P supply is the important factor.

  16. Input Loss Crop harvest Animal manures and biosolids Mineral fertilizers Plant residues Runoff and erosion Primary minerals (apatite) • Organic phosphorus • Microbial • Plant residue • Humus Mineral surfaces (clays, Fe and Al oxides) Weathering Adsorption Immobilization Mineralization Desorption Secondary compounds (CaP, FeP, MnP, AlP) Dissolution Leaching (usually minor) Precipitation The Phosphorus Cycle Plant uptake • Soil solution • phosphorus • HPO4-2 • H2PO4-1

  17. Potential Environmental Problems? Risk of environmental loss? 100 80 60 Relative crop yield, % • Soil tests are good indicators of dissolved P in runoff … • … BUT do not indicate environmental risk for a given field 40 20 0 Low Medium Sufficient Soil Test P (Sharpley et al. 1993)

  18. Phosphorus in the Watershed Sharpley, Gburek, USDA-ARS; Beegle, Penn State University

  19. Mehlich-3 P mg/kg <30 30-100 >100 Soil Test P Distribution Sharpley, Gburek, USDA-ARS; Beegle, Penn State University

  20. Vulnerability to P Loss P loss vulnerability Low (clear) Medium High Sharpley, Gburek, USDA-ARS; Beegle, Penn State University

  21. What Determines Phosphorus Fertilizer Need? ƒ Population, Land resources/fertility, Historic nutrient use patterns, Cropping diversity, Export versus domestic goals, Government policy, Current Economy…

  22. Indigenous Phosphorus supply - the net effect? Highly P def soils > 60% 40-60% 20-40% (Fairhurst et al., 1999) 0-20%

  23. Soybean yields – US/Brazil AgriStats, NASS

  24. Soybean growth – US/Brazil ? AgriStats, ANDA, NASS

  25. Soybean P removal – US/Brazil AgriStats

  26. Opportunities… • World food demand • Favorable climate • Lower land price • Low production cost • High yields with fertility correction • Improving infrastructure • Political/economical stability EC Joint Research Centre, 2002

  27. Smallholder farms - Sustainability of Slash & Burn Systems – Oxisol, Manaus, Brazil • 8 years of cultivation after initial slash & burn • 17 consecutive crops CROP Rice Soybean Corn Cowpea TREATMENT N & P K Lime & Cu S B & Zn Mn Mg Year After Burning Cravo and Smith, 1997

  28. No fertilizer: • Total yield = 1.73 t/ha Cravo and Smith, 1997

  29. Months till 50% Decrease Increase Org C 134 - Ca 23 - Mg 15 - K 5 - Al - 33 pH - 29 Zn 21 - Soil fertility decay pattern – No fertilizer Cravo and Smith, 1997

  30. NPK plus Lime Cravo and Smith, 1997

  31. **Subsistence farmers require clearing & abandoning 3 new hectares per year to produce the same amount of food on one sustainable hectare Yield Response to P • plus 3 t Aglime Applied P kg/ha 396 264 132 Cumulative yield, t/ha Control Crop Number Cravo and Smith, 1997

  32. Cerrado soil has poor fertility & can’t produce without fertilizers Gypsum+ Lime+PK = 3,780 kg/ha Seed only = 480 kg/ha DirceuBroch, Fundação MS

  33. Grain production gaps Compiled from Lopes, 1996 and Yamada, 2003

  34. 4,210 3,310 3,220 640 Seed placed, kg P2O5/ha Broadcast & Incorporated, kg P2O5/ha Soybean P response in Cerrado soil Source: Fundação MT

  35. TOP FARMER GROUPS: TO DEVELOP AND TRANSFER TECHNOLOGY

  36. Challenges • Potential for agricultural expansion is great • Projections for future production are bold • How sustainable is this production? • Maximum economic yield is always the desired goal • Adequate P is a crucial part of the yield equation responsible for reaching this goal

  37. P consumption – world comparisons (kg per arable ha) AgriStats

  38. Soybean growth – US/Brazil AgriStats, ANDA, NASS

  39. N use efficiency Crop rotation High soil P Irrigation Early seeding Seed density Variety pH & high soil P Early Seeding & high soil K Low compaction Best management practices 90 80 Yield 70 60 % Increase 50 40 30 20 10 0 (Corn results from several U.S. state’s)

  40. Within-field returns fromoptimum N/P rates (Corn) 0 100 200 300 400 500 600 $/ha 405 402 360 300 240 240 180 180 120 Relativeelevation (m) 120 South to north distance (m) 60 60 West to east distance (m) 0 12 hectares, 1997 Southwestern MN Malzer et al, U of MN

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