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Phosphorus and Potassium Nutrition of Cotton Produced Using Two Tillage Systems

D.D. Howard and R.H. Roane


 
ABSTRACT

Phosphorus (P2O5) and potassium (K2O) fertilization information for conventional- (CT) and no-tillage (NT) cotton (Gossypium hirsutum L.) production systems is limited. Research was initiated in 1994 and continued through 1998 on a Loring silt loam at the Milan Experiment Station evaluating P2O5 and K2O fertilization rates for CT and NT systems. The initial Mehlich I extractable P and K levels were low and medium, respectively. Experimental design was a split plot with tillage the main plot and P2O5- K2O rates the sub-plots. The fertilization rates included 0, 40, 80, and 120 lb P2O5/acre with 0, 30, and 60 lb K2O/acre, a total of 12 treatments replicated four times. These rates were broadcast before planting using triple-superphosphate and potassium chloride. N was applied at 80 lb/acre after planting using ammonium nitrate. D&PL 50 was planted 1995 and 1996 with D&PL 5409 planted 1997 and 1998. The ANOVA showed a tillage-by-P-fertilization-by- year interaction effect on yields. The data will be presented by tillage system. Yearly CT and NT yields were increased by P2O5 fertilization. Surface broadcasting 40 lb P2O5/acre was sufficient for increasing CT and NT yields for three of the five years. The 1995 and 1997 CT yields were increased with 80 lb P2O5/acre while the 1997 and 1998 NT yields were increased with 120 and 80 lb P2O5/acre, respectively. The 1998 yield increased with P2O5 fertilization were expressed by: Y (CT) = 1155.2838 + 4.104 P2O5 - 0.0234 (P2O5)2 and Y (NT)= 10007.5863 + 6.3006 P2O5 - 0.0363 (P2O5)2. Broadcasting 60 lb K2O/acre increased CT yields three of the five years while NT yield were increased two years of the five years from broadcasting 30 lb K2O/acre. For the other years, yields were unaffected by K fertilization.



Reprinted from Proceedings of the 1999 Beltwide Cotton Conferences pg. 1310
©National Cotton Council, Memphis TN

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Document last modified Monday, Jun 21 1999