Phosphorus Use Efficiency in Production Agriculture

Transcription

1 Phosphorus Use Efficiency in Production Agriculture Paul Fixen 2007 Fertilizer Outlook and Technology Conference Nov. 7, 2006

2 A new, not-for-profit organization Purpose: To help provide a coordinated scientific foundation for fertilizer nutrient use and to scientifically address the associated environmental issues Better Crops, Better Environment... through Science

3 IPNI Founding Members

4 A key challenge for agriculture Parameter Predicted increase in global demand for corn, rice, and wheat from 1995 to 2025* Kg/ha/yr** Global rate of yield increase, : Corn, 61 Rice, 54 Wheat, 41 Annual % * Rosegrant et al. (2002, Food Policy Research Institute) as modified by Cassman (2006) to include 5% of global grain supply in 2025 used for production of biofuel and bio-based industrial feedstocks. ** All rates of gain in cereal yields are decidedly linear over the past 40 yrs (Cassman, 2006); proportional rates of gain are based on 2004 yields.

5 U.S. corn yields, 1964 to Transgenic traits traits IPM IPM Transgenic Cons. Cons. tillage tillage y = 1.836x R 2 = 0.84 Genetic Genetic improvement improvement Increase Increase in in N N fertilization fertilization Soil Soil testing testing & & balanced balanced NPK NPK fertilization fertilization Expansion Expansion of of irrigation irrigation Corn yield, bu/a 43 years of 1.84 bu/a/yr Breaking this line while meeting environmental expectations will be a huge challenge Concept by Cassman, 2006

6 General reasons to be interested in P efficiency Recoverable P is a scarce natural resource Manufacturer Grower Consumer Potential environmental benefits to keeping P in the field U.S. Phosphate reserves Cost/tonne tonne,, Fob mine $40 25 Years World 90 Stewart et al., 2005 (ASA P Monograph) Direct economic value to the grower Increased yield Faster return on investment Lower optimum P rates in some situations $

7 Major reason for interest in efficiency is likely influenced by soil P level CA OR BC WA 24 AB SK MT WY economics NV UT AZ 25 North America 31 ppm 3.4 million samples Median Bray P1 equivalent, ppm Short term ID grower 25 economics CO 26 NM MB 17 ND MN SD NE ON WI MI 39 IA 49 IL IN OH MO 3629 KS KY 18 TX 21 OK AR 17 LA TN 21 MS AL GA PQ PEI NB ME NS PA FL NY MD VT NJ WV VA NC 103 SC DE CT MA NH RI Avoiding P loss to water 2005

8 The appropriate definition of P efficiency depends on the intended use of the result Yield increase P applied Fertilized uptake check uptake P applied Agronomic efficiency Recovery efficiency (Single yr or long-term) Removed by crop P applied Removal efficiency

9 One intended use: basis of incentive payments in farm programs NRCS: Multiple level nutrient management Precursor to 3-tier CSP structure Objective: intensify nutrient management beyond the minimums of Form : Performance-based approach considered Calculating NUE as a basis for incentives? Considered: Recommended/Applied Removed/Applied (removal efficiency) Performance-based dropped in favor of practicebased

10 Efficiency vs. effectiveness: a single-season crop response example Greatest effectiveness Lowest efficiency Yield response Lowest effectiveness Greatest efficiency Applied P

11 Typical objectives of nutrient use Provide economically optimum nourishment to crop Minimize nutrient loss from the field Contribute to system sustainability soil fertility or other soil quality components Utilization efficiency is not enough P use must be effective in meeting the objectives of nutrient use Can be highly efficient and totally ineffective (low P rate at a low soil P test)

12 Agronomic and recovery efficiency decline as soil fertility increases (lb wheat/lb applied P) Garcia, % 1 st yr recovery Where do we advise growers to be? Near 0% 1 st yr recovery 1 st yr recovery is a poor indicator of long-term profitability

13 High efficiency is not enough Wheat yield, bu/a Olsen soil test at end of 5-yr: 15 ppm 8 ppm 5 ppm Amount broadcast initially, lb P 2 O 5 /A Highest P efficiency (about 30% recovery ) but not effective 0 Wager et al., Annual seed-placed P 2 O 5, lb/a

14 14 recovered/70 applied = 20% VS 70 removed/70 applied = 100% Fertilizer P 70 lb P 2 O 5 /A Fertilizer Phosphorus Efficiency Typical values for 185 bu/a corn in the Midwest P removed with harvest 70 lb P 2 O 5 /A P in crop residue 30 lb P 2 O 5 /A 14 lb P 2 O 5 /A 86 lb P 2 O 5 /A Soil P Recovery efficiency:useful in short-term; term; Removal efficiency: useful in long-term when combined with soil P change

15 System level efficiency Nutrients recovered in the crop plus the net change in available soil nutrients Dobermann et al, 2005

16 Agronomic and recovery efficiency decline as soil fertility increases (lb wheat/lb applied P) Garcia, % 1 st yr recovery Near 0% 1 st yr recovery If replacing removed P maintains soil P, system efficiency is 100%

17 The value to the grower of practices that improve P efficiency Soil modification Genetic improvement P sources & coatings Impact on effectiveness in meeting grower objectives Placement Timing General cultural practices

18 Right rate, right time, right place does not always result in the highest efficiency,, but should offer the greatest effectiveness in accomplishing grower objectives Optimizing profitability Minimizing nutrient loss Providing system sustainability

19 Recovery and removal efficiencies for P Area Term (years) P NUE (%) Source & method World (recovery efficiency) Smil, 2000; survey World Many (recovery efficiency) Smil, 2000; survey* US Annual 87 (removal efficiency) PPI, 2002**; partial budget * A global literature review is underway by Syers, Johnston and Curtin; funded by FAO, IFA, IMPHOS, PPI/PPIC, and TFI that will offer more detailed information. ** 0.35 lb P 2 O 5 /bu used for removal by corn.

20 Phosphorus use compared to crop removal for a corn-soybean rotation (2 yrs) (avg of 2004 & 2005) Iowa Illinois Indiana lb P2O5/A M F R lb P2O5/A M F R lb P2O5/A M F R Removal efficiency % 168% 121% 0 F Fertilizer P consumption/a planted to principle crops in M Annual recoverable manure P for 1997 x 2 (NRCS, 2000). R Crop removal for 2004 and 2005 corn and soybean yields.

21 P budget for the state of Illinois by watershed Median Bray P-1 P 1 level for 2005 crop = 36 ppm State total, million lbs P 2 O 5 + Applied fertilizer (2005) Recoverable manure (1997) 77 - Crop removal (2005) 1,075 Net budget -385 Removal efficiency 156%

22 Short-term vs long-term P efficiency Long-term P efficiency Generally high in North America Removal efficiency of 85-90% Long-term recovery efficiency in research of 40-90% Short-term term P efficiency Much lower than long-term efficiency Single-year recovery seldom higher than 20%; often less than 10%

23 Where short term recovery is important Time value of money always has some importance Short land tenure

24 Percent of land in farms rented or leased in 2002 in the U.S. U.S. 28.4%

25 Where short term recovery is important Time value of money always has some importance Short land tenure Limited operating capital and sub-optimal soil test levels

26 Percent of soil samples requiring annual P fertilization to avoid profit loss in most major crops 2005 Crop Year

27 Where short term recovery is important Time value of money always has some importance Short land tenure Limited operating capital and sub-optimal soil test levels Soils with severe P fixing potential Threat to water quality

28 Summary The value of practices that improve P efficiency is dependent on impact on effectiveness in meeting grower objectives Optimizing profitability Minimizing nutrient loss Providing system sustainability Long-term fertilizer P efficiency in North America is usually high but short-term efficiency can be quite low Short-term efficiency is most important when: Land tenure is short or uncertain Operating capital is limited and soil test levels are below optimum Soils have high P fixing potential Fields or field areas pose a threat to water quality

29 Phosphorus Use Efficiency in Production Agriculture 2007 Fertilizer Outlook and Technology Conference Nov. 7, 2006