Lowbush Blueberry Response to Different Phosphorus/Nitrogen Ratios

Abstract

Lowbush blueberries (Vaccinium angustifolium Ait.) in three commercial fields were treated with 67.2 kg P/ha from triple super phosphate (TSP), monoammonium phosphate (MAP), or diammonium phosphate (DAP) and compared to a control in a randomized complete-block design with 12 blocks. Correction of P deficiency by fertilizers with different ratios of P to N was assessed by leaf nutrient concentrations. Samples of stems collected in July from three 0.03-m2 quadrats per treatment plot indicated MAP and DAP had no effect on dry weight of stem tissue, but increased average dry weight of leaf tissue. P and N Leaf concentrations were raised to higher levels by MAP and DAP than by TSP. TSP had no effect on leaf N concentrations but raised leaf P concentrations compared to controls. Stem length, flower buds per stem and flower bud density were increased by both MAP and DAP, but not TSP. MAP and DAP increased fruit yield by about 340 kg/ha compared to the control.