POTASSIUM UPTAKE BY COTTON AND CHANGES IN SOIL CHEMICAL PROPERTIES RESULTING FROM THE DEEP PLACEMENT OF DRY FERTILIZER

G.L. Mullins, D.W. Reeves, and C.H. Burmester

ABSTRACT

Field studies were conducted in 1991 on a Norfolk soil (Typic Kandiudults) to evaluate K uptake by cotton as affected by K placement and to determine changes in soil K and agricultural limestone. Potassium uptake was evaluated in an ongoing field test that was established in 1989. Measurements were taken from 5 treatments: 1) no-K check without in-row subsoiling, 2) no-K check with in-row subsoiling, 3) 90 lb K2O A-1 surface applied without in-row subsoiling and 5) 90 lb K2O A-1, deep placed. Changes is soil chemical properties were evaluated in soil treated with 90 lb K2O A-1 or 1500 lb limestone A-1. Potassium uptake and seed cotton yields were higher for the surface broadcast application of K with in-row subsoiling. The deep placement K treatment had a K uptake per plant that was equivalent to the no K in-row subsoiled check treatment. A higher K uptake resulted from the surface broadcast treatment due to the limited soil volume affected by the deep K treatment. Sampling of deep placement treatments showed that when K and limestone were deep placement treatments showed that when K and limestone were deep placed in the Norfolk soil, the fertilizer was placed in a 2 inch wide bank which extended no more than 2.5 inches above the bottom of the subsoil track. Thus, the volume of soil affected was not great enough to result in efficient K uptake which demonstrates that for Alabama soils the deep placement of K for cotton is not justified.





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Document last modified July 8, 2004