7 th International Wheat Conference November 29, 2005 Mar del Plata, Argentina

1. TILLAGE INTENSITY, CROP ROTATION, and FERTILIZER TECHNOLOGY for SUSTAINABLE WHEAT PRODUCTION … NORTH AMERICAN EXPERIENCE 7th International Wheat Conference November 29, 2005 Mar del Plata, Argentina T.L. Roberts and A.M. Johnston Potash & Phosphate Institute

2. Introduction • North America is a world leader in no-till crop production

3. USA25.3 Brazil23.6 Argentina16.0 Canada13.4 Australia9.0 Paraguay1.7 Indo-Gangetic-Plains 1.9 Bolivia0.6 South Africa0.3 Extent of no-tillage adoption worldwide, million hectares, 2004/05. Spain0.3 Venezuela0.3 Uruguay0.3 France0.2 Chile0.1 Colombia0.1 China0.1 Others (estimate) 1.5 Total 94.6 Source: J. Hassell, Conservation Technology Information Center, personal communication

4. Introduction • North America leads the world in no-till crop production • USA produces about 60 billion t wheat and exports 30 billion t • Canada produces 26 billion t and exports 18 billion t

5. Northern Great Plains • Total area about 125 M ha • 52 M ha in crop production • Wheat is the dominant crop, followed by barley and oats • Corn is dominant only in the southern regions

6. Northern Great Plains • Canola is the dominant oilseed, grown mainly on the Canadian prairies • Dry peas and lentils … crop diversification option, but represent small proportion of cropping mix

7. Northern Great PlainsEnvironmental Conditions • Severe … cold winters and hot summers • Moisture is limiting • 300 to 500 mm of annual precipitation; 165 to 300 during the April to July growing season • Frost free period … 83 to 157 days • Soils are frozen for 4 to 6 months … minimizing microbial activity, nutrient release, and crop residue decomposition

8. No-till Wheat Production • Farmers in Canadian prairies and Northern Great Plains pioneered wheat production in reduced tillage systems. • No-till, or direct-seeding, is used on about ~third of U.S. wheat farms and half the Canadian wheat area.

9. No-till Wheat Production • Erosion control is the main reason for adopting no-till in much of the world, but in Canadian prairies … improved moisture efficiency

10. Soil zones of the Canadian prairies. • About 30 M ha of cultivated land • Spring wheat is the principal crop • Rotations … historically included high proportions wheat and summerfallow, but fallow has been declining and no-till area is increasing

11. No-till area in the Canadian prairies. Source: B. McClinton, Saskatchewan Soil Conservation Association

12. Trends in cropping intensity in the Canadian prairies. Average rotation length* Soil zone 1976 1980 1985 1990 1995 1998 Brown 1/1.1 1/1.1 1/1.3 1/1.3 1/1.3 1/1.6 Dark Brown 1/1.4 1/1.5 1/2.1 1/2.2 1/3 1/4 Black and Gray 1/2.2 1/2.6 1/4.9 1/4.9 1/6.7 1/10 *Interpret rotation 1/1.1 as one year fallow to 1.1 year in crop Source: Campbell et al., 2002

13. Cropping Systems • Growers now incorporate cereals, oilseeds, pulse crops, and forages into their rotations. • Wheat still dominates, but the improved water conservation gives growers greater flexibility.

14. Soil Changes Related to Tillage • Tillage accelerates the natural processes of soil degradation • Erosion, salinization, and acidification increase • amount and quality of organic matter decreases • Reduced tillage … greater crop residues accumulate on the soil surface

15. When residues accumulate … • Less wind and water erosion … improved soil quality • Increased water infiltration and less evaporation • Cooler soil temperatures … slower nutrient release, reduced diffusion, less root growth

16. When residues accumulate … • Changes in nutrient cycling … increases in N immobilization … eventually increased N mineralization • Immobile nutrients tend to accumulate at the soil’s surface • Soil pH may decline • Fertilizer management becomes more important

17. 70 1300 60 1200 Conventional Till Conventional Till 50 1100 Zero Till Zero Till Phosphorus, mg/kg 40 1000 Potassium, mg/kg 30 900 20 800 Silty Clay Soil 10 700 Silty Clay Soil 600 0 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 500 Depth, cm. Depth, cm. 400 300 Effect of zero and conventional tillage on P and K distribution in a Manitoba silty clay Source: Grant and Bailey, 1994

18. Fertilizer Management • Fertilizer management in no-till seeding requires careful management to optimize nutrient use efficiency • Soil characteristics, climate, crop type, and agronomic practices impact nutrient use efficiency

19. Fertilizer Management • N is the most yield limiting nutrient world wide, followed by P and K • Broadcasting N onto surface covered residue is not efficient

20. Fertilizer Management • In-soil band placement of N is usually the most effective … reduces immobilization, but applying all the crop’s N requirements can be challenging • P and K applied in bands minimizes fixation and increases early season uptake … especially when applied as a starter

21. Yield increase from starter P in a Saskatchewan fallow-wheat-wheat rotation, 1967-2004 Mean Fallow = 342 kg/ha Stubble = 197 kg/ha Source: R.P. Zentner, Agriculture and Agri-Food Canada

22. F-W-W (N+P) F-W-W (N) Influence of starter P on soil test P in the wheat phase of a Saskatchewan fallow-wheat-wheat rotation, 1967-2004 Olsen P, kg/ha Source: R.P. Zentner, Agriculture and Agri-Food Canada

23. Fertilizer Management • All P needs for wheat can be safely applied at seeding … not so for N and K • Too much N and K can reduce germination and delay emergence resulting in poor stands and lower yields

24. Many factors influence how much fertilizer can be safely applied with the seed Row spacing Seed bed utilization (SBU) Soil texture Soil moisture Fertilizer Management • Soil variability • Fertilizer placement • Seed furrow opener • Fertilizer source • crop

25. 30 cm 10 cm 20 cm Row Spacing • The amount of fertilizer that can be safely applied with the seed decreases as row spacing increases • Row spacing ranging from 10 to 30 cm … higher concentrations of P in wider rows had no effect on yield (SK and MB research)

26. Seed Bed Utilization • Measure of the amount of soil used for applying fertilizer. • Calculated as: Width of seedrow %SBU = X 100 row spacing

27. 25% 12% 8% 30 cm 10 cm 20 cm Seed Bed Utilization • Assuming a 2.5 cm seed row (knife opener) and a 10 cm row spacing SBU = 2.5/10 x 100 = 25%

28. Seed Bed Utilization • Heavier textured soils tolerate more N because the increased cation exchange and water holding capacity reduces ammonia toxicity … a major cause of germination and seedling damage

29. Approximate Safe Rates of Urea-N (kg/ha) that can be applied with wheat. 2.5 cm spread (Disc or knife) Row spacing, cm 15 23 30 SBU, % 17 11 8 Light 22 17 17 Medium 34 28 22 Heavy 39 24 24 Source: Henry et al., 1995

30. Approximate Safe Rates of Urea-N (kg/ha) that can be applied with wheat. 2.5 cm spread 7.5 cm spread (Disc or knife) (Sweep) Row spacing, cmRow spacing, cm 15 23 30 15 23 30 SBU, % SBU, % 17 11 8 50 33 25 Light 22 17 17 45 34 28 Medium 34 28 22 56 45 39 Heavy 39 24 24 67 56 45 Source: Henry et al., 1995

31. Specialized Seeding Equipment • Many growers have adopted the use of specialty seeding equipment that places fertilizer in a separate band from the seed No-Till Seeding Original Equipment No-Till Seeding Present Equipment

32. Side Band Openers – Many to Choose From

33. Stealthtm Opener 2.5 cm 2.5 cm

34. 3.8 x 7.2 cm 3.8 x 3.8 cm

35. Urea and anhydrous ammonia (NH3) are the two main N sources used by the region’s farmers • NH3 is common in higher moisture regions, where higher N rates are required to optimize yields

36. Wheat Seedling Response to Side Banded N Form x N Rate AB and SK Locations

37. Wheat Yield Response to Side Banded N Form x N Rate AB and SK Locations

38. Horizontal, Not Vertical Separation of NH3 Band is Critical to Avoiding Damage

39. Sulfur is the third most limiting nutrient in the Northern Great Plains • Estimated 30% of the acreage in Canadian prairies is S deficient • SO4-S soil test is difficult due to variability of SO4 in the field and release of organic S S deficient wheat

40. S Fertilizer • S is normally applied as elemental S or as as SO4 • Elemental S requires microbial oxidation • Temperature, moisture, aeration, pH and particle size influence oxidation • Application of elemental S in the spring or near planting is not recommended for annual crops because oxidation is too slow • Mixtures of bentonite and elemental S are available which increase the dispersion of S particles and increase oxidation rates

41. Average wheat yield response to applied S in Alberta soils with no previous S application -S +S* Yield No. of --- kg/ha --- inc., % trials Gr. Wooded soils 1422 1619 14 12 Breton‡ 949 1830 93 20 U of A§ 2482 2731 10 8 * 15 kg S/ha as Na2SO4 ‡ Average total S=100 mg/kg, § Average total S=670 mg/kg Source: Doyle and Cowell, 1993

42. Average wheat yield response to applied S in Alberta soils with 20-year history of S application -S +S Yield No. of --- kg/ha --- inc., % trials Breton‡ 1 774 1178 52 5 2 2059 2225 8 5 3 1690 2737 62 5 4 2523 3641 44 4 U of A§ 1 3379 3659 8 4 2 1999 2023 1 4 * 15 kg S/ha as Na2SO4 ‡ Average total S=100 mg/kg, § Average total S=670 mg/kg Source: Doyle and Cowell, 1993

43. Effect of N, P, and S fertilization on wheat yields in Alberta. Treatment N P2O5 S Yield Yield Inc. ------------- kg/ha ------------- % 1 0 0 0 2310 -- 2 0 0 22 2550 10 3 18 22 0 2480 7 4 18 22 22 3020 31 Source: Doyle and Cowell, 1993

44. Influence of N and P on wheat grown on fallow and stubble in a Dark Brown soil in southern Alberta. Rotation sequence, 13-yr Ave. yield, kg/ha Fertilizer, kg/ha Fallow wheat Stubble wheat N P F-W F-W-W F-W-W Cont. W 0 0 2775 2332 1203 1156 0 20 2802 2641 1176 1284 45 0 2722 2460 1519 1505 45 20 3031 2654 1908 1747 Letters in bold face represent the phase of the rotation the yield was determined. Source: Campbell et al., 1990

45. Concluding Comments • Understanding soil nutrient behavior and its implications to fertility management is important to maximize nutrient use efficiency and wheat production in no-till • Soil testing is the best available tool to estimate soil nutrient levels and make appropriate fertilizer recommendations

46. Thank You