Tobacco Production Update Bob Pearce, Gary Palmer, Andy Bailey Extension Tobacco Specialists Kenny Seebold Extension Plant Pathologist
Topics • Nitrogen sources for tobacco • Revised nitrogen rates for tobacco • Sucker control options • No MH options • Variety update • Disease update
Nitrogen Fertilizer Issues • Economics • Leaf prices down • N fertilizer prices up • Price tied to natural gas • Transportation costs up • Nitrosamine concerns • Tobacco companies want less N applied • Quality concerns • Too little: thin body, poor yield • Too much: delayed maturity, fat stems
Ammonium Nitrate Issues • Most common N source for tobacco growers • Homeland security concerns • Can be used to make explosives • Easy availability • Some manufacturing plants have closed • Tighter supplies • Higher costs • Sales regulations • Permits needed to purchase large quantity? • Some dealers reluctant to stock?
Alternative N Sources • Anhydrous ammonia (82% N) • Lowest cost per unit of N • Limited availability • Special equipment needed • Stored as liquid under pressure • Special injectors needed • Used in illegal meth production • Feasible only if equipment already available • Placement concerns • Delayed uptake • Phyto-toxicity if close to plants
Alternative N Sources • Anhydrous ammonia (82% N) • Reaction in soil • NH3 + 2O2→ H+ + NO3- +H2O • Same lime requirement as AN • Suggestions for use • Inject 6 to 8 inches deep • 7 to 10 days before setting
Alternative N Sources • Ammonium sulfate (21% N) • Specialty fertilizer • Use on acid loving crops • Use on high pH soils • Relatively high cost per unit N • Limited availability • Soil reaction • (NH4)2SO4 + 4O2→ 4H+ +2NO3-+ SO42- + 2H2O • 3X lime requirement of AN • Not feasible for large scale use on tobacco
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
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
Alternative N Sources • Calcium – Ammonium Nitrate (27% N) • Ammonium nitrate mixed with lime • 78% ammonium nitrate • Theoretically similar to ammonium nitrate • Can impregnate some chemicals ? • Relatively high cost? • Availability? • Limited practical experience
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 • High cost • Low analysis – high transport cost
Effects of Ammonium Nitrate Application on Soil pH Anhydrous Ammonia, Urea, UAN solutions : similar
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.
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.
Nitrogen Source StudyHarrison Co. – Keith Smith Farm 100 units AN Broadcast Sidedressed with 170 units each, AN = AmmoniumNitrate, U= Urea, CN = Calcium Nitrate, SN = Sodium Nitrate
Conventional Fertility TrialMonroe Co. – Al Pedigo Farm Broadcast Sidedress Number = lbs of product, AN = AmmoniumNitrate, CN = Calcium Nitrate, SN = Sodium Nitrate, U= Urea
No-till Fertility TrialMonroe Co. – Al Pedigo Farm Broadcast Sidedress Number = lbs of product, AN = AmmoniumNitrate, CN = Calcium Nitrate, SN = Sodium Nitrate, U= Urea
Effects of Sidedressing Different Sources of Nitrogen on Burley YieldElliot Co. – Tracy D. Kitchen Farm 450 Ammonium Nitrate Broadcast followed by 100 lb/a of Nitrogen Sidedressed. Am = Ammonium, Ca = Calcium & Na = Sodium. There were no significant differences.
Effect of Nitrogen Source on Burley YieldMarshall Co. – Glen Thompson Farm 2579 2605 2650 2684 225 150 units Urea Broadcast Sidedressed with 100 units each at sidedressing, Ca = Calcium and Na = Sodium
Revised Nitrogen Rates • AGR-1 will have a new table for N on tobacco • Based on crop history (same as old) • No additional N for continuous tobacco • Soil drainage formally considered • “Typical” recommendation 50 lbs. N/A less • Rate lower if sidedressing is practiced • Economically sound recommendations • Reduce incidence of over-application
Effects of Nitrogen Rates on Burley Tobacco at Spindletop Farm (Maury Silt Loam) • MacKown, Sutton and Crafts-Brander – 1994
Effect of N rate and method of application on burley tobacco yield. If 1/3 or more is sidedressed reduce total amount of N by 15 to 25 lbs./A
Summary • Encourage growers to compare costs and consider alternative N sources • Revised N rates • Rates lowered by about 50 lbs./A • Will not significantly lower yield • Improved quality • Promotes desired chemical properties • Reduce rate if sidedressing is practiced