Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 16, 2010
Publication Date: May 1, 2010
Citation: Tewolde, H., Adeli, A., Sistani, K.R., Rowe, D.E. 2010. Potassium and magnesium nutrition of cotton fertilized with broiler litter. Journal of Cotton Science. 14:1-12. Interpretive Summary: Broiler litter is a mixture of mostly manure and wood chips used as bedding in broiler chicken houses. It has been shown to be an effective nitrogen and phosphorus fertilizer in cotton production. Litter also contains substantial amounts of potassium, magnesium, and other essential plant nutrients. This research investigated if cotton receives adequate potassium fertilization from the application of the commonly recommended litter rate of 2 ton/acre and if magnesium derived from the same amount of litter improves cotton magnesium nutrition. The research was conducted in 2002 to 2004 at two commercial farms at Coffeeville and Cruger, Mississippi. The soil at Coffeeville had much lower soil test potassium and magnesium than the soil at Cruger. But, cotton at both locations benefited from potassium derived from 2 ton/acre litter, a rate previously found to be inadequate in meeting the nitrogen need of cotton. Cotton did not respond to the magnesium supplied by any amount of litter up to 3 ton/acre. The magnesium nutrition of cotton was more dependent on whether the cotton received adequate nitrogen fertilization than on the external supply of magnesium.
Technical Abstract: Poultry litter has been shown to be an effective cotton fertilizer and is usually applied as a source of N. Litter contains substantial amounts of K also, but whether the K need of cotton can be met by the commonly recommended litter rate has not been investigated or documented. Litter also contains Mg but whether litter-derived Mg benefits cotton production is also not documented. The objectives of this research were to determine if cotton receives adequate K fertilization from the application of the commonly recommended litter rate of 4.5 Mg ha-1 and if Mg derived from the same amount of litter improves cotton Mg nutrition. The research was conducted in 2002 to 2004 at two locations in Mississippi (Coffeeville, no-till and Cruger, conventional-till) with contrasting levels of extractable soil K and Mg. Cotton at each location was fertilized with 2.2, 4.5, or 6.7 Mg ha-1 broiler litter in an incomplete factorial combination with 0, 34, or 67 kg ha'1 N as urea-ammonium nitrate solution (UAN). The soil at Coffeeville had 49 mg kg-1 Mehlich 3 extractable K (M3K) and 21 mg/ka Mehlich 3 extractable Mg (M3Mg). The soil at Cruger had more than four times M3K (233 mg kg-1) and nearly 22 times more M3Mg (465 mg kg-1). The results showed concentrations of K in petioles, bulk leaves, stems, and reproductive parts increased in a linear proportion to increasing litter rate at both locations. The results also showed cotton received adequate K from 4.5 Mg ha-1 litter, a rate previously found to be inadequate in meeting the N need of cotton. Unlike K, Mg concentration did not respond to litter rate but showed a strong response to supplemental UAN-N rate, which suggests the external supply of N may be more important to cotton Mg nutrition than the external supply of Mg. The results show that K nutrition of cotton depends on the rate of applied litter and therefore applied K, while the Mg nutrition is dependent on whether the cotton received adequate N fertilization.