Over a period of 5 years, the cotton lint yield increased by foliar applied potassium in California, USA. Greatest increases in lint yield were observed from applications beginning two weeks after first bloom. A typical lint yield response curve of K foliar materials (such as potassium nitrate) is found in Figure 1, applied in a single spray of 5 kg K2O/ha (11 kg potassium nitrate/ha), to cotton after first bloom, grown in the San Joaquin Valley, California, USA. Up to 135 kg extra cotton lint yield per hectare (+11%) can be observed.
Figure 1. Typical response curve of K foliar materials applied to cotton after first bloom, Weir, University of California.
Weir, B. 1998. Foliar potassium bumps cotton yields. Fluid Journal. Fall 1998. p. 1-2.