Nutrient Balances in North American Soils

Transcription

1 Nutrient Balances in North American Soils Fertilizer Outlook and Technology Conference Tampa Marriott Waterside Hotel October 28, 2009 Terry L. Roberts President, IPNI

2 Nutrient balance and 4R nutrient stewardship Resource use efficiencies: Energy, Labor, Nutrient, Water Biodiversity CROPPING SYSTEM OBJECTIVES Healthy environment Nutrient loss Water & air quality Soil erosion Adoption Nutrient balance Soil productivity Yield Net profit Productivity Durability Ecosystems services Farm income Profitability Return on investment Quality Yield stability Working conditions

3 Ten tenets of sustainable soil management Analogous to a bank account, it is also not possible to take more out of a soil than what is put in it without degrading its quality Thus, managed ecosystems are sustainable in the long term if the output of all components produced balance the input into the system. Source: Rattan Lal. J. Soil and Water Conservation 64(1): 20-21A

4 Nutrient Budgets... useful insights into the balance between nutrient inputs and outputs in crop production unlike financial budgets only partial budgets because of inaccuracies in determining inputs/outputs p

5 Nutrient additions to the field also include N fixation by legumes, atmospheric deposition and nutrients in irrigation water Partial Nutrient Budget Losses also include soil erosion, leaching, denitrification, volatilization

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7 Partial N budgets for North America, billion lb (average of ) US Canada NA Applied dfertilizer Recoverable manure N fixation Crop removal Balance (inputs removal) Removal to use ratio with manure Removal to use ratio without manure Crop removal =N removed in harvested portion of alfalfa, soybeans, peanuts, 49% of lentils, and 54% of dry peas; It was assumed that any fixed N not recovered in the harvested crop was countered by soil N taken up during the growing season. Source: Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR Technical Bulletin

8 Partial P 2 O 5 budgets for North America, billion lb (average of ) US Canada NA N.A. Applied fertilizer Recoverable manure Crop removal Balance (inputs removal) Removal to use ratio with manure Removal to use ratio without manure Source: Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR Technical Bulletin

9 Partial K 2 O budgets for North America, billion lb (average of ) US Canada NA N.A. Applied fertilizer Recoverable manure Crop removal Balance (inputs removal) Removal to use ratio with manure Removal to use ratio without manure Source: Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR Technical Bulletin

10 Partial budgets for six leading corn states, billion lb (average of ) N P 2 O 5 K 2 O Applied fertilizer Recoverable manure N Fixation 8.4 Crop removal Balance (inputs removal) Removal to use ratio with manure Removal to use ratio without manure Source: Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR Technical Bulletin

11 Ratio of P and K removal to fertilizer use plus manure nutrients applied to corn, soybeans, wheat, and cotton in the U.S. Rem moval/use :1 line P 2 O K 2 O Source: Plant Nutrient Use in North American Agriculture, PPI/PPIC/FAR Technical Bulletin

12 NuGIS Nutrient Use Geographic Information System Project is about mapping and spatial analysis of nutrient use data. Initially sponsored by the PPI/TFI Nutrient Use Task Force then continued by IPNI Phase I: discovery of data sets and sample analysis Phase II: focused on national net nutrient budgets at the county and watershed levels. national maps of commercial fertilizer, manure and nutrient removal from major crops for the years of the Ag Census 1987, 1992, 1997, 2002, and 2007.

13 Legend for maps to follow Removal/Use Ratio Ratio of nutrient removed by crops to fertilizer nutrient applied plus nutrients in recoverable manure. Crop removal is less than fertilizer use building soil fertility Balanced budget (removal = use) Crop removal is greater than fertilizer use depleting soil fertility

14 N US =

15 N N Use>Removal Removal = Use Removal>Use

16 P US =

17 P P-2007 P removal exceeds use in much of the Corn Belt U.S Use>Removal (excess P) Removal = Use Removal>Use (mining P)

18 K US = 1.30 West 2 4 East Use>Removal Removal = Use Removal>Use

19 K K-2007 K removal exceeds use 1.2 but soil levels are 0.8 generally v. high K removal exceeds useby1020% 10-20% in western Corn Belt Use>Removal (excess K) Removal = Use Removal>Use (mining K) 0.9 U.S

20 Fertilizer consumption in the U.S., Fertilizer consumptio on, million t ons Short tons N P2O5 K2O 0 Data Source: AAPFCO (2008) and H. Vroomen, TFI (est )

21 A closer look at where we were in North America before use reductions (using NASS, AAPFCO, and the Ag Census data) Soils do not create P or K nutrients They have an indigenous amount and store what is added d to them In a sustainable agriculture, the P and K removed by crops must eventually be replaced

22 Change in annual crop removal over 20 yrs, short tons K 2O: K 2 O: million tons 9.5 million tons P 2 O 5 : P 2O 5: million tons 6.1 million tons

23 Nutrient removal by crops in the U.S. (N removal by alfalfa, soybeans and peanuts excluded) metric to ons Million 10 9 y = x N 7 6 y = x K 2 O 5 4 y = x P 2 O 5 P 2 2 O 5 K 2 O Annual increase: 1000 metric T short T

24 Nutrient removal by crops K 2 O: (short tons) Fertilizer nutrient sales K 2 O: mil Increasing at 78,000/yr 5.1 mil increasing at 5,000/yr P 2 O 5 : P 2 O 5 : mil 6.1 Increasing at 60,000/yr 4.5 mil Increasing at 22,000/yr

25 Comparison of nutrient removal by crops in the U.S. to nutrient applied as fertilizer and in recoverable manure (removal is average of ; fertilizer use is from 2007) Million sh hort tons P 2 O 5 10 * Even with the assumption that 4 all recoverable manure P and K is applied where it is 2 needed, the P budget is barely 1 balanced and the K budget 0 remains extremely negative K 2 O * Based on 2007 livestock census using Kellogg et al.(2000) procedure.

26 Changes in Corn Belt P and K Budgets Removal/Use K-1987 K-2007 Elimination of most of the K surpluses. P-1987 P-2007 From P deficits and surpluses to mostly deficits. Green = excess nutrients Red = depleting nutrients

27 Changes in state or province soil fertility levels from 2001 to Median P 31 ppm 2005 Median K 154 ppm Corn Belt changes from 2005 to 2010? Indications are that soil levels will be lower More fields will require annual P and K fertilization P and K agronomic demand should increase

28 Fertilizer consumption in the U.S., Fertilizer consumptio on, million t ons Short tons N P2O5 K2O 0 Data Source: AAPFCO (2008) and H. Vroomen, TFI (est )

29 Agronomic implications of recent P and K use reductions? Loss of crop yields ildand profits? Depletion of soil nutrient reserves? Negative nutrient budgets?

30 2009 US Corn Yield Forecast at bu/a a New Record Corn yield, bu/ /A y = x r² = 0.87 In spite of large K and P fertilizer use reductions ? USDA-NASS, 8/2009.

31 Lots of calibration data in North America

32 MEY concept illustrates the impact of reduced application 100 Relative yield, % Level of input

33 MEY concept illustrates the impact of reduced application impact depends where you are on the yield curve

34 Impacts of historical K management g/ha yield, M ze grain Mai Randall et al., 1997a,b Soil test K : Ample P + 56 kg K 2 O/ha/yr : Ample P, no K 2 O Ample P and K * * * K stopped Year K, mg/kg g Soil test

35 Soil tests vary in their background noise Phosphorus Potassium Soil nutrie ent supply Observed Calculated Soil nutrie ent supply Observed Calculated Time Time

36 P removal to use ratios for the I states e ratio Remov val to us IA IL IN Median Bray P, ppm IA 25 IL 36 IN

37 P budgets for Iowa, Illinois, and Indiana per acre planted dto principle i crops IA IL IN lb P 2 O 5 /A* Fertilizer applied (2007) Recoverable manure (2007) Crop removal (avg of 06/07/08) Balance = *Based on avg of acreage. Typical Bray1 or Mehlich 3 decline, ppm: If continued for 5 years: Median soil test levels in 2005, ppm Assuming 18 lb P 2 O 5 /ppm.

38 P budgets for Iowa, Illinois, and Indiana per acre planted to principle crops with no P fertilizer IA IL IN lb P 2 O 5 /A* Fertilizer applied (none) Recoverable manure (2007) Crop removal (avg of 06/07/08) Balance = *Based on avg of acreage. Typical Bray1 or Mehlich 3 decline, ppm: If continued for 5 years: Median soil test levels in 2005, ppm Assuming 18 lb P 2 O 5 /ppm.

39 K budgets for Iowa, Illinois, and Indiana per acre planted dto principle i crops IA IL IN lb K 2 O/A* Fertilizer applied (2007) Recoverable manure (2007) Crop removal (avg of 06/07/08) Balance = *Based on avg of acreage. Typical soil test K change, ppm: If continued for 5 years: Median soil test levels in 2005, ppm Assuming 8 lb K 2 O/ppm.

40 K budgets for Iowa, Illinois, and Indiana per acre planted to principle crops with no K fertilizer IA IL IN lb K 2 O/A* Fertilizer applied (none) Recoverable manure (2007) Crop removal (avg of 06/07/08) Balance = *Based on avg of acreage. Typical soil test K change, ppm: If continued for 5 years: Median soil test levels in 2005, ppm Assuming 8 lb K 2 O/ppm.

41 Nutrient reduction impact on soil test levels and yield based on a budget approach May see little impact on soil test levels after one year of reduced rates May see little negative impact on yield if soil test levels are above the critical level

42 Summary Nutrient budgets are important to farmers and to society they are indicators of sustainability. Weaknesses exist in our current capacity to accurately evaluate nutrient budgets at appropriate resolution: Crop nutrient removal coefficients Census data for specific nutrient use expenditures AAPFCO county level fertilizer sales data

43 Summary Crop nutrient removal is increasing faster than nutrient use nationally and in most key production areas. Most of the Corn Belt appears to be mining soil P and many areas appear also to be mining soil K intensive monitoring of soil fertility is a critical BMP.

44 The End Better Crops, Better Environment through Science