Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fluid Journal 1996-1998
2 Fluid Journal Fall 1998 1-2 1200 1240 1280 1320 1360 1400 1440 Yield - lbs/A Control At bloom 3-4 4-5 5-6 Weeks after bloom Figure 2. Effect of foliar KNO3, on cotton yields, Weir, University of California, 1993. 1150 1190 1230 1270 1310 1350 Yield - lbs/A Control At bloom 2 2-4 Weeks after bloom Figure 3. Effect of foliar K2SO4, on cotton yields, Weir, University of California, 1994. generally the length of the field (about a quarter mile), and were replicated four times. All tests were conducted using a completely randomized block statistical design. In general, the times of K applications were: • at bloom • followed by weekly applications • including multiple applications at bloom and one week later; at bloom and two weeks later, etc. Amounts of K per application were generally 4.5 lbs/A of K2O, regardless of material applied. Figure 1 shows a typical response curve to K foliar material applied to cotton after first bloom. Steady response 1992. There was a benefit to K applied at bloom, but the greatest increase in lint yield was at about two weeks after first bloom. 1993. Strikingly similar results were obtained again, using Acala Maxxa and Pima S-7 cottons. Greatest yield advantages were measured from plots that received foliar K from two to three weeks after first bloom. Foliar applications later in the season responded less and the effect was similar whether the source of K was potassium nitrate KNO3 (Figure 2) or potassium sulfate K2SO4 or SOP (Figure 3). 1994. Several forms of K were applied to cotton through foliar sprays. Potassium nitrate, potassium thiosulfate (KTS), and SOP were all applied at rates of 4.5 lbs/A of K2O per application. Many treatments received more than one application. Responses to foliar K occurred in every case when compared to untreated controls. Findings were consistent with earlier results in that the greatest responses occurred with applications about two to three weeks after first bloom. 1995. Potassium sulfate, KTS, and potassium nitrate were applied as foliar sprays at bloom, followed by applications 2-4 weeks later. Potassium sulfate gave the greatest yield increases where 4.5 lbs/A of K2O were applied at bloom and again two weeks later. The test results were similar to previous years. Greatest yield response occurred when potassium sulfate or potassium thiosulfate was applied about 2-4 weeks after first bloom.
Fluid Journal 1993-1995
Fluid Journal 1999-2001