Response of Pecan to Annual Soil Band Applications of Phosphorus and Potassium

摘要

Phosphorus (P) and potassium (K) deficiencies were identified in a 'Pawnee' pecan [Carya illinoinensis (Wangenh.) C. Koch] orchard. Deficiencies of P and K have traditionally been difficult to correct in pecan. Broadcast application of P rarely results in a positive response. Broadcast applications of K frequently require 3 or more years before a positive response was noted, particularly in soils with high clay content. A 4-year study was initiated on 10-year-old trees using soil band-applied P, K, blended P plus K, and a non-treated control. Rates were based on trunk cross-sectional area adjusted annually for tree growth. Phosphorus application alleviated leaf deficiency symptoms, increased leaf P concentration, and improved flowering. However, P application resulted in darker kernels than the control or K-treated trees. Band-applied K was not associated with observed leaf symptoms but increased leaf K above the recommended minimum level and increased the percentage of number-1 kernels. Band-applied P or blended P plus K suppressed leaf K concentrations. Blended P plus K applied as a band appeared to improve return bloom 2 of 3 years, although no improvement in leaf K concentration was noted.