Effect of Surface Application of Nitrogen Fertilizer Sources on
Cotton Yields and Quality inA Conservation Tillage
System
Charles H. Burmester
Extension Agronomist
Auburn University
Test Information
• Location: Tenn. Valley Research and Extension Center• Soil Type: Decatur Silt Loam• Variety : DP&L 454 Bt/RR• Tillage : No-Till Wheat Cover• Planting Date: April 24th
• Preplant N : 24lb/A• Plot Area: Irrigated
Fertilizers
• 34% Ammonium Nitrate
• 46% Urea
• 44.6% Urea + Calcium Thiosulfate 4.5%
• 42.3% Urea + Calcium Thiosulfate 7.0%
• 46% Urea + Agrotain(1 gal/Ton)
N RATES
60, 90 LB/A
Surface Applied June 5th
Rainfall 0.51 inch June 12th
Cotton 4-5 Leaf Stage
Fertilizers
Fertilizers
Fertilizers
Fertilizers
Cover Crop
TEST SITE
Data Collected
• Cotton leaf samples in mid July - cotton in 3rd week of bloom
• NAWF measurement in early August
• Cotton yields and quality
Pre-Harvest DataTreatment NAWF %N
60 Amm-Nit 4.3 abc 3.67 cd
60 Urea 3.8 bcd 3.41 e
60 U-Cats-4.5 3.7 bcd 3.43 e
60 U-Cats-7.0 3.6 cd 3.41 e
60 U-Agrotain 3.5 d 3.48 de
90 Amm-Nit 4.7 a 3.98 ab
90 Urea 3.9 bcd 3.85 abc
90 U-Cats-4.5 4.1 abcd 3.93 ab
90-U-Cats-7.0 4.0 abcd 3.81 bc
90-U-Agrotain 4.4 ab 4.04 aLSD (0.05 =.75 LSD (.05) = 0.23
Pre-Harvest Data
• Nutrient analysis of cotton leaves revealed no differences due to treatment in concentration of P, K, Ca or Mg.
• P levels averaged 0.27%
• K levels averaged 1.75%
• Mg levels averaged 0.34%
• Ca levels averaged 1.50%
Seed Cotton Yields
1500170019002100230025002700290031003300350037003900
Amm Nit Urea U-Cats-4.5 U-Cats-7.0 U-Agrotain
60
90
b
ac
c
bbc
a
bc
a
bc
a
LSD (0.05) =269CV = 5.4%
Cotton QualityTreatments Mic Len Str. Unif Lint%
60 Amm-N 4.67 1.09 28.6 82.8 0.46
60 Urea 4.40 1.10 28.8 83.3 0.46
60 U-Cats-4.5% 4.30 1.10 29.1 83.1 0.46
60 U-Cats-7.0% 4.30 1.10 28.7 83.1 0.47
60 U-Agrotain 4.37 1.11 28.9 83.0 0.46
90 Amm-N 4.50 1.10 28.7 82.7 0.46
90 Urea 4.50 1.10 28.6 83.2 0.46
90 U-Cats-4.5% 4.53 1.11 28.9 83.3 0.46
90 U-Cats-7.0% 4.60 1.09 29.1 83.0 0.46
90 U-Agrotain 4.57 1.10 27.9 82.5 0.45
Conclusions
• Increasing N fertilizer rates from 60 to 90 lb/A increased NAWF, Leaf N, and yields with all N sources.
• Cotton yields using Agrotain and Thiosulfate fertilizers were not significantly different than Ammonium Nitrate in this test.
Conclusions
• Cotton yields using urea fertilizer were significantly lower than yields produced using ammonium nitrate at both N fertilizer rates.
• Agrotain and thiosulfate fertilizers produced significantly higher cotton yields than urea fertilizer at the 90 lb/A rate of N fertilizer.
Conclusions
• Both Agrotain and the Thiosulfate fertilizers tested may be useful in reducing N loss from urea under a high residue conservation tillage cotton system.
Acknowledgement
• Thanks to Joe Duck with Agrotain International and John Clapp with Tessenderlo Kerley for their product support