The effect of potassium soil amendments,trenching and foliar sprays on the mineral content,growth, yield and fruit quality of sweet cherry (Prunus avium L.) and prune (Prunus domestica L.)

Abstract

Potassium sulfate was applied to established, non‐irrigated, K deficient trees on fine textured soil by banding, placing in augered holes and injecting into the soil. Additional trees received a heavy compost mulch in early fall. Trenches were dug in the fall beside trees to break roots and then were backfilled with K₂SO₄, dolomite lime or a combination of the two. One percent K solutions of KNO₃ or K₂SO₄ were sprayed on trees four times during the growth season.

Sweet cherry trees only responded to compost mulch applications within two years. August midshoot leaf K, leaf N and fruit size were increased within one year however tree growth and yield were not affected. Fruit size and shoot growth were partially dependent on August leaf K level.

August midshoot leaf K of prune trees was increased within one growing season by all treatments except trench plus lime. Trees receiving compost also had increased levels of leaf N, P, Ca, Mn, Fe, Cu and B. Yield and shoot growth were increased only by compost mulch applications. Fruit size was partially dependent on August leaf K levels.