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Fluid Journal : Fluid Journal 1996-1998
1 Fluid Journal Summer 1998 Summary: Almond meat yields in 1997 were different between treatments under the micro-sprinkler system, but there were no significant differences between treatments in the single- or double-line drip irrigation systems. There was a consistent trend for all potassium treatments to give higher yields than control under the micro- sprinkler system. Yields did not show a consistent trend as rates of potassium were increased, particularly with injected potassium sulfate (K2SO4) and mono-potassium phosphate (MKP). Banded K2SO4 under the micro- sprinkler resulted in good yields compared to other sources and rates', whereas banded K2SO4 did not yield as well under single- or double-line drip systems. Declining leaf potassium (K) levels in high-yielding irrigated almond orchards on the West side of the Sacramento Valley and other areas of the state have given growers cause for concern on how best to apply K. Irrigation is accomplished with different systems that apply water to a limited soil volume or wetted area up to flooding the entire soil surface and wetting all of the soil. Fertilizers generally are banded or broadcast before irrigation or winter rains, or applied through irrigation to help place nutrients in wetted soils, or move them into the soil where plant roots will contact the potassium. Good uptake by trees has been reported in low-volume irrigation systems or those with smaller wetted area systems, even though K does not readily move in the soil. Because some fertilizers are not dissolved easily or water quality prohibits trouble-free injection, growers are using soil applications as an alternative. However, the availability of several new liquid K formulations (e.g., sulfate, phosphate, and thiosulfate) makes it easier to inject into irrigation systems. Drs. R.D. Meyer, J.P. Edstrom, L.J. Schwankl Potassium Boosts Almond Yields Via Irrigation Yield differences over control are significant in micro-sprinkler system but not in single- or double line drip systems. Given the above history, it seemed prudent to evaluate the relative efficiency of K uptake from several sources and methods of placement. The objectives of our experiments are to: 1) determine how different placement, sources, and rates of K applied through single-line, double-line, and micro- sprinkler irrigation systems affect almond yields, growth, and nutrient concentrations of leaves 2) assess the extent of K movement in soil under different placement, source, and rate of application through the three irrigation systems. Figure 1. Almond meat yields from banded K2SO4 versus and rate of K injected through micro-sprinkler irrigation system at Nickels Soil Laboratory, Meyer, et al., 1997. 0 2,200 Lbs. K O/tree 2 2,300 2,400 2,500 2,600 2,700 2,800 2,900 3,000 Lbs meat/A Banded KSO 24 KSO 24 MKP KTS KCI 1*2*4*1#2#4#1!2!2o24 * # O
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