Management of Key Nutrients in Tobacco

1. Management of Key Nutrients in Tobacco Dr. Bob Pearce and Dr. Paul Denton Extension Tobacco Specialists

2. Essential Soil Nutrients • 16 generally accepted (some say up to 19) • C, H,O from air or water • Other 13 from soil

3. Nutrients of Concern in Tobacco • Always • N, P and K: basic soil test and fertilization • Ca and Mg: basic soil test and liming • Under some conditions • Mo, B • Rarely or never in KY • S, Zn, Cu, Fe • Concern about detrimental effects • Mn, Cl

4. A Good Burley Crop 3000 lb/aRemoves • 200 lbs of N • Mid Season to Topping • 35 lbs of P2O5 • Early • 240 lbs of K20 • Mid Season to Harvest

5. General growth curve for burley tobacco Reduced nutrient uptake Maturation Rapid top growth Nutrient uptake Slow top growth Rapid root growth

6. Nitrogen • Tobacco highly responsive • Deficiency • Pale green/yellow • Stunted growth • Nitrate form is taken up by plants • Many fertilizer sources converted in soil. • Lowers soil pH • Some N may be lost • No reliable soil test to predict availability

7. Nitrogen Loss From Soil • Leaching • Coarser soils • Denitrification • Wetter soils, wet springs • Often more important than leaching

8. Effects of Excessive Nitrogen Rank growth Sucker control problems Delayed maturity Curing problems Decreased quality Soil acidification Negative effects on cured leaf chemistry Alkaloids Nitrates Tobacco-specific nitrosamines (TSNAs)

9. Price Per Unit of Nitrogen for Selected Fertilizer Materials

12. Effects of Nitrogen Rates on Burley Tobacco at Spindletop Farm

13. If 1/3 or more is sidedressed reduce total amount of N by 15 to 25 lbs./A

14. Urea Ammonium Nitrate Ammonium Phosphates Ammonium Sulfate UAN (liquid) Anhydrous ammonia Nitrate of Soda (Sodium Nitrate) Potassium Nitrate Calcium Nitrate Nitrate of Soda- Potash Ammonium Nitrate SourcesSources

15. With Proper Liming and Recommended Rates • Any Source OK Preplant • Ammonium Nitrate or UAN OK for Timely Sidedressing • Urea and Ammonium Sulfate Not Preferred for Sidedressing • All nitrate sources good, but expensive

16. Ammonium Nitrate Issues • Most common N source for tobacco growers • Homeland security concerns • Can be used to make explosives • Easy availability • Dealers under new regulations to secure supply • May have to register to purchase • Some manufacturing plants have closed • Tighter supplies • Higher costs

17. New N Source • Dolomite – Ammonium Nitrate (27-0-0) • Ammonium nitrate mixed with dolomitic lime • 80% ammonium nitrate • Theoretically similar to ammonium nitrate • Relatively high cost • Availability? • Bagged only? • Limited practical experience

18. Alternative N Sources • Urea (46% N) • Intermediate cost • Handling similar to ammonium nitrate • Can impregnate some chemicals • Same lime requirement as AN • Converted to nitrate in the soil • Subject to loss if surface applied • Apply to dry soil • Incorporate or water in • Delayed uptake (Don’t use for sidedress) • Feasible alternative if managed properly

19. Alternative N Sources • Non Pressure Solutions (28 – 32% N) • Intermediate cost • Mixture of urea, ammonium nitrate, and water • Relatively easy to transport, store, and apply • Most nurse tanks • Many types of sprayers • Corrosive to equipment • Should be incorporated • Can be used a a carrier for spray applications • Limited availability • Feasible for tobacco production

20. Alternative N Sources • Ammonium sulfate (21 % N) • High cost • Handling similar to ammonium nitrate and urea • Most acidifying of all N sources • All ammonium source like urea • Converted to nitrate in soil • Delayed availability • Not good for sidedress • Urea generally a better choice

21. New Bagged 34-0-0 • Half ammonium sulfate, half urea • All ammonium N • More acid forming than urea alone • Requires same time for conversion as urea • Priced like ammonium nitrate • Might as well use urea

22. Alternative N Sources • Sodium Nitrate (16% N) • Calcium Nitrate (15.5% N) • Sodium-Potassium Nitrate (15% N) • Immediate uptake (good for sidedress) • Good for low pH soils • Erratic availability • Very high cost • Low analysis – high transport cost • Security concerns

23. Effect of Broadcast & Sidedress Nitrogen Source on Burley YieldFayette County – Robert Eads Farm Broadcast (150 units/ acre) Sidedress (100 Units/ acre)AN = Ammonium Nitrate, CN = Calcium Nitrate

24. Conversion to Nitrate in Soil

25. Effect of Liming an Acid Soil Prior to Use of Urea and Sodium Nitrate Sources of Nitrogen Both N sources applied at 225 lb N/A pre-plant. Soil pH (water) measured at midseason of each year. Soil pH before liming was 5.4.

26. Effect of Liming an Acid Soil Prior to Use of Urea and Sodium Nitrate Sources of Nitrogen Both N sources applied at 225 lb N/A pre-plant.

27. Effects of Ammonium Nitrate Application on Soil pH

28. Importance of pH • Direct Effect of Acidity (< 4.5) • Al and Mn Toxicity • Nutrient Availability • Disease Incidence

29. pH for Tobacco Target pH = 6.6 Apply lime at pH 6.3 or less

30. Effect of Soil pH onthe availabilityof nutrients and potentialtoxins

31. Mn Toxicty • Caused by low soil pH • not enough lime • too much N fertilzer • Stunts growth • May reduce yield 200 to 300 lbs./A • Soil test and add lime as needed

32. Manganese Toxicity • pH > 5.5 – Probably Will Not Occur • pH 5.5 to 5.0 – May Occur Depending on Soil, N Management, Other Factors • pH < 5.0 – Highly Likely

33. Efficient P and K Fertilization

34. Probability of Response to P and K Fertilizer • Low soil test – High probability of response • Medium soil test – Medium to low probability • High soil test –Low probability • Very high soil test – No response expected

35. Phosphorous and potassium fertilization of tobacco • Use soil test to determine need • 70 % of tobacco patches do not need additional P • 30 % of tobacco patches do not need additional K • Fall apply to take advantage of price/availability • Scout fields for signs of deficiency • adjust rates to fit specific soil conditions • Do not use muriate of potash in spring • Chloride is detrimental to leaf quality • Use animal manure in moderation

36. Fertilizer Costs per Acre by Soil TestBurley Tobacco – UK

37. Phosphorus Deficiency

38. Sources of Phosphorus • Diammonium phosphate (DAP) – 18-46-0 • Monoammonium phosphate (MAP) – 11-52-0 • Triple super phosphate (TSP) – 0-46-0

39. Potassium Deficiency

40. Potassium Deficiency

42. A Good Burley Crop 3000 lb/aRemoves • 200 lbs of N • Mid Season to Topping • 35 lbs of P2O5 • Early • 240 lbs of K20 • Mid Season to Harvest

43. What about bandingK fertilizer ???

44. Band Application of Potassium Fertilizers Broadcast 16 “ band 4 “ band Drill band

45. Tobacco yield response to banding

46. Rate of banded K to produce same yield as a given rate of broadcast K

47. What about banding fertilizer ??? • Allows reduced rates • More labor than broadcast • Risk of crop injury • For many producers, more to gain from following soil test • May allow additional gains in a good soil fertility program

48. Sources of Potassium • Sulfate of potash: 0-0-50 • Intermediate cost • Muriate of potash: 0-0-60 • Lower cost • Quality issues for tobacco • Sul-po-mag: 0-0-22 • High cost • Soda-potash: 15-0-14 • Potassium nitrate: 13-0-44 • High cost • Limited availabilty

49. High chloride in tobacco • Poor cured leaf color • dingy, muddy, variegated • Imparts unpleasant flavor and aroma to smoke • Reduces burn rate • Cause cured leaf to hold moisture • moldy stems / fat stems • high case can lead to rot during storage • nitrosamines ??

50. Influence of Cl on tobacco combustibility