The possibility of occurrences of beltwide zinc deficiencies in cotton have been suggested by some individuals. Very little published information is available about cotton response to zinc fertilizers in the Delta of Mississippi. Two greenhouse and two field tests were conducted in 1988 with zinc variables to measure cotton response to zinc. The pH of all soils evaluated were between 6.2 and 6.8.

Cotton in both greenhouse experiments was grown in 3 gallon clay pots. In the first experiment, zinc was foliar applied as a 1% zinc sulfate solution twice a week after the plants reached 6 inches in height. At about first flower, total above ground plant dry weights were measured. Plant dry weights of zinc treatments were equal to the control.

In the second greenhouse experiment, zinc-EDTA was mixed thoroughly with the soil before planting at a rate of 4 lbs Zn per acre -6 inches. Zinc treatments were added in combination with P and K. Above ground dry weights were measured at two weeks after first flower when plants were about 2 feet tall. In all cases, applications of zinc reduced plant dry weights and plant height below comparable controls.

Both field tests were conducted in the north-central Delta in the Sumner-Glendora area. In the first field test, EDTA chelated zinc was applied as a 3-inch band on the soil surface over the seed at planting at a rate of 0.5 lbs Zn per broadcast acre. In the second field test, EDTA chelated zinc was applied broadcast and shallow incorporated before planting at a rate of 0.6 lbs Zn per acre. Lint yields from both tests were numerically lower than the control but were not significantly different from the controls in either test.

The results of these 4 tests indicate that insurance type applications of zinc fertilizers to cotton would not be advisable in the Delta of Mississippi.