Nutrient Management Research Database

This study evaluated the efficiency of potassium uptake as a function of source, placement, and irrigation system. Almond meat yields in 1997 varied between potassium treatments under the micro-sprinkler system, but there were no significant difference between potassium treatments in the single- or double-line Drip 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 and mono-potassium phosphate. Banded potassium surface under the micro sprinkler resulted in good yields compared to other sources and rates, whereas banded potassium sulfate did not yield as well under single- or double-line drip systems.

• On multiple plots, liquid potassium was injected into the irrigation systems and applied to the trees via the single- or double-line drip or micro-sprinkler, and on other plots dry potassium was applied to the soil surface in a band 3 to 4 inches wide, 4 feet from the tree on both sides of the tree row.
• There were 72 test plots.

• Average almond yields with potassium treatments were:
  • 2,400 meat lbs/almond for single-line drip;
  • 2,445 meat lbs/almonds for double-line drip;
  • 2,619 meat lbs/almond for micro-sprinkler.
• All potassium treatments produced higher yields than the untreated almond trees. However, as potassium rates were increased, there was not a consistent trend in yields.
• Banded potassium under micro-sprinklers produced good yields compared to other potassium sources, which was surprising.
• Banded potassium did not yield well under the two drip systems, since the drip system was not wetting the area where the potassium had been banded.