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Fluid Journal : Fluid Journal 1996-1998
3 Fluid Journal Summer 1998 and October samples under the double- line drip system, but indicated some increases over control, particularly the injected K2SO4 treatments in the July samples. Under the micro-sprinkler system on all three sample dates, there was a consistent trend for all K treatments to result in higher leaf K concentrations versus control. Under this system, leaf K concentrations on any of the three sample dates did not show a consistent trend as rates of K were increased, especially with injected K2SO4 and MKP. As might be expected, KCI increased K concentrations in leaves. Chloride levels also increased, although not to concentrations high enough to affect tree production. Design and treatments Fertilizers. Liquid K2SO4 was applied as 1-0-8, potassium thiosulfate (KTS) as a liquid (0-0-25), and MKP as a dry granular added to water. KCl was dissolved in water and applied as a liquid. Although KCl is the most economical source of K, the addition of chloride represented a potential Replications. Since there was an uneven number of plots for the three irrigation systems, the trial was initiated with the following replications: single- line drip, 4; double-line drip, 2; micro- sprinkler. 2. Plots. Each plot size was 5 trees with a 15-foot in-row spacing and 20 feet between rows. There were 72 plots. Varieties. NonPareil and Butte varieties were used in our K experiments on almonds. Soil was an Arbuckle gravelly loam (Fine-loamy, mixed, thermic Typic Haploxeralf) having a pH just below neutral (6.7). Location. Experiments were conducted at the Marine Avenue location at Nickels Soil Laboratory, Arbuckle, California. Dr. Meyer is extension soils specialist and Dr. Schwankl is extension irrigation specialist, both at Davis; Edstrom is farm adviser in Colusa County; all are with the University of California. detrimental effect. A preliminary experiment with 9 rates of KCl indicated no toxicity. Therefore, when the product was included in our large study, it was applied at one-quarter the highest rate used in the earlier study. Dry granular potassium sulfate (0-0-50) was fall applied on soil's surface in a band approximately 3 to 4 inches wide, approximately 4 feet from tree on both sides of tree row. Timing. To improve uniformity of application, the two main irrigation systems---one for drip (both single-and double-line) and one for micro- sprinkler---were turned on approximately 3 hours before any fertilizer was injected. Liquid materials were split injected during May and June in two to four applications. Treatments for the three systems were randomly assigned. Injectors. Liquid injection systems were designed, built, and installed to inject fertilizer for each 5-tree plot. Injection cylinders were 6 inches in diameter and constructed at various lengths to accommodate different volumes of liquid fertilizer having a range in K concentration.
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