Foliar fertilization of cotton, Gossypium hirsutum and G. Barbadense, has been a subject of researchers since 1992 in California. The practice has expanded from its limited beginnings to widespread use for supplying supplemental nitrogen and potassium. Yield and economic advantages have been realized by researchers, and growers alike. Replicated field tests were conducted annually from 1992 to 1997 to evaluate the effects of foliar N and K on cotton yields and quality. K₂SO₄, KNO₃, and KTS were applied at various timings beginning at first bloom, in single and multiple applications. Rates of K₂O were kept constant at 5.0 Kg/ha for each application.

All three materials, K₂SO₄, KNO₃, and KTS resulted in increased lint yields when compared to an untreated control. Maximum positive benefits occurred when applications were made between one and three weeks after first bloom. Increases in lint yields have generally been up to 100 Kg/ha.