1 / 23

Urease Inhibitor (Agrotain ® ) Effects on N-Use Efficiency in No-Till Cotton

Urease Inhibitor (Agrotain ® ) Effects on N-Use Efficiency in No-Till Cotton. Jac J. Varco 1 , Robert E. Earnest 1 , and Jimmy D. Johnson 2 Plant and Soil Sciences Dept. (1) Mississippi State University, Mississippi State, MS, (2) Agrotain International, Collierville, TN. INTRODUCTION.

Rita
Download Presentation

Urease Inhibitor (Agrotain ® ) Effects on N-Use Efficiency in No-Till Cotton

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Urease Inhibitor (Agrotain®) Effects on N-Use Efficiency in No-Till Cotton Jac J. Varco1, Robert E. Earnest1, and Jimmy D. Johnson2 Plant and Soil Sciences Dept. (1) Mississippi State University, Mississippi State, MS, (2) Agrotain International, Collierville, TN

  2. INTRODUCTION Findings from a 10-y study in Miss. (Parvin et al., 2003): • AN highly profitable due to high yield achieved at a lower rate of N (80 lb/acre) • Subsurface banded UAN efficient, but lower profit due to lower yield • Surface dribbled UAN profitable at a higher rate of N (120 lb/acre) • Urea most profitable at a high rate of N (120 to 180 lb/acre)

  3. Current trends: • Decreasing availability of ammonium nitrate to growers • Increasing fertilizer N prices • Increased acreage of no-till cotton

  4. Research results: • decreased NH3 loss with urease inhibitor (Beyrouty et al., 1988) • N losses up to 30% of surface applied urea (Beyrouty et al., 1988) • [N-(n-butyl)] thiophosphoric triamide (NBPT) is an effective urease inhibitor (Bremner et al., 1991) • NBPT treated urea increased N-use-efficiency for rice (Aly et al., 2001)

  5. N Fertilizer Use in MS(Nutrient short tons, 2004) • Ammonium nitrate 20,089 • Nitrogen solutions (UAN) 57,119 • Urea 31,867

  6. Price/lb N • AN $0.448 • UAN (32%) $0.328 • Urea $0.364 Average N rate, MS 2005 =120 lb/ac

  7. Urea Hydrolysis Increased potential for NH3 volatilization w/no-till due to greater urease activity on crop residues (NH2)2CO + H2O  2NH3 + CO2 Urease enzyme is a catalyst for hydrolysis reaction

  8. OBJECTIVES • Determine effects of fertilizer N source and placement on N-use-efficiency by no-till cotton • Determine effects of a urease inhibitor (UI) on N-use-efficiency of urea N-sources by no-till cotton

  9. METHODS • General • No-till • N rate 120 lb/acre, split 50% @planting and early square • 15N enriched fertilizer @  1.4% • Varieties: ST 4892 BR (2005), DP 445 BR (2006) • Urease inhibitor in Agrotain® [N-(n-butyl)] thiophosphoric triamide or NBPT • Automated rainfall data collection

  10. Treatments • No N check • Ammonium nitrate (AN) broadcast • Urea broadcast • Urea w/UI broadcast • UAN subsurface banded • UAN dribbled • UAN w/UI dribbled • Randomized complete block, four replications

  11. Urea, AN, and urea treated with UI were broadcast within microplots using a pump type sprayer

  12. UAN subsurface banded, UAN dribbled, and UAN w/UI dribbled were applied 8” from drill using a 2 oz syringe

  13. Screens placed under rows to collect residues

  14. Elemental and isotope analysis were determined w/an automated C/N analyzer coupled to a mass spectrometer

  15. Rainfall/Fertilization 2005

  16. Rainfall/Irrigation/Fertilization 2006

  17. Cotton N Content Response

  18. N Derived From Fertilizer Response

  19. Fertilizer N Recovery Response

  20. Price of Agrotain® • $45/gal • 1 gallon treats 1 ton dry urea • 2.3 quarts treats 1 ton UAN 32% • Price of urea w/Agrotain /lb N $0.413 • Price of UAN 32% w/Agrotain /lb N $0.368 • Price of AN $0.448

  21. Cost Benefit at 120 lb N/acre Urea • $43.68/acre w/o Agrotain • $49.56/acre w/Agrotain • 22 lb N/acre increase in efficiency @ $0.36/lb urea N = $8.01/acre = $2.13/acre cost benefit UAN 32% • $39.36/acre w/o Agrotain • $44.16/acre w/Agrotain • 26 lb N/acre increase in efficiency @ $0.33/lb UAN N = $8.53/acre = $3.73/acre cost benefit

  22. CONCLUSIONS • UI treated urea improved no-till cotton N use efficiency comparable to AN • UAN dribbled with UI was as effective as soil incorporation in no-till cotton production

  23. When to use a urease inhibitor? • Conditions for NH3 volatilization • no-till • temperatures above 65°F • high organic matter/surface residues • high humidity • unincorporated urea

More Related