A Factorial NPK Field Experiment with Strawberry,Var. Royal Sovereign

Two phases of a factorial NPK field experiment with strawberry are described and discussed. The object of the experiment was to study the effect of NPK fertilizers on soil fertility, leaf nutrient status, crop yield, and the relationships of these.

Treatments had significant effects on soil pH and soil exchangeable-K at all depths sampled, and on 0·5 N acetic acid-soluble P at 0-6 in. and 6-12 in. depths only.

Nitrogenous fertilizer had no significant effect on crop yield or fruit grade; phosphatic fertilizer had a small but significant effect on crop yield in the first season only; potassic fertilizer was effective mainly in the later stages of the experiment when it enhanced crop yield.

Nitrogenous fertilizer increased leaf-N significantly in all seasons; phosphatic fertilizer increased leaf-P in one season only; potassic fertilizer increased leaf-K in all seasons.

Leaf-K, soil exchangeable-K, soil potassium potential (AR°_e) and crop yield were significantly related with each other. When individual plot values for leaf-K and exchangeable-K were correlated with crop yield, 90% of the yield variance was due to factors other than potassium.