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Potato Science Lecture 12

Potato Science Lecture 12. Fertility Management. Irrigated Potato Production . Important Nutrients. Primary macronutrients Nitrogen Phosphorus Potassium. Total potato plant N, P, and K U ptake. Nutrient Uptake (lb/ac). Days After Emergence.

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Potato Science Lecture 12

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  1. Potato Science Lecture 12 Fertility Management

  2. Irrigated Potato Production

  3. Important Nutrients Primary macronutrients • Nitrogen • Phosphorus • Potassium

  4. Total potato plant N, P, and K Uptake Nutrient Uptake (lb/ac) Days After Emergence

  5. Total Potato Plant N, P, and K Uptake Rates at Aberdeen K N Nutrient Uptake Rates (lb/ac/day) P Days After Emergence

  6. Early-Season Soil Nutrient Placement

  7. Foliar Fertilizer Placement Dry Fertigation P, K N

  8. Relative Nutrient Mobility in Soil • Nitrogen – Mobile (nitrate>urea>ammonium) • Potassium – moderately low mobility • Phosphorus – low mobility

  9. Nitrogen • Necessary for protein and chlorophyll • Used in large quantities by plants • Quantity available fluctuates rapidly • Shortage associated with marked yield loss • Application important in all soils

  10. Soil N Cycle LEACHING (NO3-)

  11. Nitrogen Deficiency Symptoms • General chlorosis (pale green color) • Younger leaves turn darker green, old leaves remain yellow • Upward cupping of deficient leaflets when severe

  12. Potato Variety Nitrogen Response Trials Aberdeen, 2005

  13. Soil Analysis • One composite sample per 20-25 acres • 0-12 inch sampling depth for potatoes • Combine 10-20 samples (zig-zag pattern) • Random but accurate samples

  14. Total N Recommendations for Russet Burbank Potatoes

  15. Nitrogen Fertilizer Management Program • Apply up to 25-60% of N prior to planting • Apply remainder of N (40-75%) through the irrigation system during tuber development according to crop requirements • Slow release or controlled release N fertilizers applied preplant can be used to reduce N leaching

  16. Preplant N applications Nitrogen (partial application) 25-30% on sandy soils 30-40 % on sandy loam soils 40-60 % on silt loams Nitrogen fertilizers – urea, mono-ammonium phosphate, ammonium sulfate, ammonium polyphosphate

  17. In-Season N Applications Target = Total Seasonal N Requirement - preplant + sidedress applications • Begin after tuber initiation and adjust according to tuber bulking rates and weekly petiole N concentrations • Cut-off 3 to 4 weeks before vine kill

  18. Calculating In-Season N Application Rates • Based on lb N/ac/day or week, which changes according to crop demand • Once tuber bulking begins, weekly crop N requirements can be estimated based on relationships between tuber growth rate and plant N uptake • Daily N uptake rates for different potato cultivars range from about 2 to 5 lb N/ac/day depending on the tuber-bulking rate • Can be applied as dry or liquid N fertilizers

  19. Calculating In-Season N Application Rates • Russet Burbank requires about 3-4 lb N/ac/day (20-25 lb N/week) to prevent the loss of both N and dry matter from the tops and roots to the tubers during tuber bulking • Assuming 75-80% plant N uptake efficiency for injected N fertilizer, about 30 lb N/ac would satisfy crop N requirements for a week • Adjustments to projected rates to account for N mineralization should be based on weekly petiole nitrate tests

  20. Total Yield Response to N for A03158-2TE and Russet Burbank at Aberdeen ID, 2013 610 506 460 423

  21. Tissue Analysis • Petiole analysis the most common • Sample 4thpetiole • Sample under consistent conditions • Dry the tissue immediately • Private and public labs • Base applications on sufficiency

  22. A03158-2TE Petiole Nitrates, 2013

  23. Recommended petiole and soil (0-18 inches) NO3-N concentrations for Russet Burbank potatoes during different growth stages TuberTuber Sample Vegetative Initiation Bulking Maturation ------------- NO3-N (ppm) ------------- Petiole----- 20,000-25,000 15,000-20,000 10,000-15,000 Soil> 20 20 15-20 < 15

  24. From Rowe, 1993

  25. Factors Affecting Petiole Nitrogen Concentrations Plant Factors: photosynthesis dry matter production N metabolism transpiration Soil Factors: temperature moisture mineralization NH4+/NO3- physical conditions Root Factors: carbohydrate supply root health root length / depth

  26. Impact of Weather on Soil N Supply, Soil N Losses, and Crop N Demand Critical Time Period – N builds up in (or is applied to) soil before plant uptake and may be lost Amount of N fertilizer needed… Potato N Uptake …In normal year Soil/ Plant N Soil mineral N, Normal year …in year with wet spring Soil mineral N, Wet spring Spring Summer Fall

  27. Potato Yield Response to N Fertilizer Following Fall or Spring Plowing of Alfalfa, Aberdeen 2002 Potato Rotation Study Rexburg, ID 2003-2005 Fall plow Spring plow Yield (cwt/acre) Nitrogen Rate (lbs N/acre)

  28. Russet Burbank potato yields as influenced by N rates after alfalfa, wheat, or maize averaged across 2004 and 2005 seasons 83 119 164

  29. Phosphorus • Second most critical nutrient • Essential for energy transfer • Critical for root growth • Generally low in soil availability • Rapidly tied up by soil • Management is long-term • Application important in all soils

  30. From Rowe, 1993

  31. Total Potato N, P, and K Uptake Nutrient Uptake (lb/ac) Days After Emergence

  32. dry matter P Phosphorus and Dry Matter Accumulation Accumulation/maximum Days After Emergence

  33. Soil P Buffering Capacity • Depletion of solution P brings absorbed P into solution to maintain equilibrium • Rate of establishing new equilibrium depends on rate of desorption from absorbed forms and rate of diffusion (i.e., the withdrawal rate is proportional to the size of the bank)

  34. Phosphorus Precipitation on CaCO3 • P adsorbed to CaCO3 surfaces forming ion clusters • Clusters allow for nucleation of Ca-P crystals • Common in calcareous soils of Southern Idaho

  35. 500 ppm P 50 ppm P 25 ppm P 100 ppm P 10 ppm P 0 ppm P Calcite equilibrated for 10 days

  36. Ammonium Phosphates Reaction pH

  37. P Fertilizer Granule H2O adsorption precipitation Ca2+ H3PO4 CaHPO44

  38. Recovery of Fertilizer P • Plants recover 5 to 20% • Remainder reacts with soil components • Residual fertilizer P builds up soil P to increase future availability

  39. Phosphorus Fertilizer Program • Adequate P concentration in bulk soil to maintain optimal P concentration • Starter bands to enhance early season P availability • Maintenance / building of soil P levels

  40. Preplant Phosphorus Options • Ammonium Phosphates - liquid and dry • Avail • Humic Acids • Controlled Release P In-Season P Sources – APP (10-34-0) and phosphoric acid

  41. Broadcast Band

  42. Preplant P Fertilizer Recommendations for Russet Burbank Potatoes Percent Free Lime Soil Test P (0-12 inch depth) ppm 0 4 8 12 ------------ lb P2O5/acre ---------------- Apply an additional 40 to 80 lb of P2O5/acre as a starter at planting for soil test P levels below 30 ppm. Add 25 lb P2O5/acre as a starter for additional 100 cwt/acre above 400 cwt/acre.

  43. Dry Matter Balance Y = 0.76X – 0.7 r2 = 0.67 Dry Matter Balance (total / tubers) 0.22% P = sufficiency level (0.22) Average P in leaves (%) Westermann and Kleinkopf, 1985

  44. Phosphorus Fertigation • Maintain petiole P concentration above 0.22% through tuber bulking • 30 to 40 lb P/A in late July can increase total P uptake 4 to 5 lb/ac • Typically use APP (10-34-0) or Phosphoric acid

  45. Potassium • Used in large quantities by plants • Important in translocation of nutrients • Easily leached in sandy soils • Some soils naturally low • Application important in all soils

  46. Total Potato N, P, and K Uptake Nutrient Uptake (lb/ac) Days After Emergence

  47. Forms of Potassium in Soil Mineral 5,000 - 25,000 ppm Non-exchangeable 50 - 750 ppm Exchangeable 40-600 ppm Solution 1-10 ppm

  48. K Absorption by Plants • Primarily by diffusion and mass flow • Related to K intensity (solution K) • Diffusion : 85 - 95% of K uptake • Mass Flow : 5 - 10% of K uptake • K quantity (Q) = exchangeable K

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