Pear Responses to Split Fertigation and Band Placement of Nitrogen and Phosphorus

Abstract

Single broadcast application of nitrogen (N) and phosphorus (P) on the soil surface results in low use efficiency of applied N and P in pear (Pyrus communis) production systems in Oregon and the Pacific northwestern United States. A field experiment was conducted from 2005 through 2006 to evaluate the effects of split fertigation and band placement as alternate N and P management practices in ‘Anjou’ pears growing on a Parkdale loam soil near Parkdale, OR. Measurement and analysis of tree nutrition, fruit yield, quality, and storability, as well as indigenous soil nutrient supply was the scope of the experiment. To evaluate fertilizer management practices on pear growth and productivity, the following four treatments were tested with a randomized complete block design replicated four times: 1) broadcast application of N and P on the soil surface in a 10-ft-wide, weed-free strip centered on the tree row, 2) band placement of N and P on both sides of tree rows in 1 × 1-ft ditches (width × depth), 3) 1 × 1-ft ditches were dug using the band placement equipment, the dug soil was completed returned to the ditch without any fertilizer, and the broadcast application of N and P on the soil surface was applied on a 10-ft-wide, weed-free strip centered on the tree row, and 4) fertigation of N and P split into five equal applications throughout the growing season. Nitrogen and P fertilizers were applied to treatments 1, 2, and 3 at 100 lb/acre N and 55 lb/acre P, while treatment 4 received only 80 lb/acre N and 44 lb/acre P. The 2-year average results show leaf N and P concentrations in the fall were increased by 10.0% and 10.6%, respectively, with split fertigation compared with broadcast application on the soil surface. Band placement increased leaf N by 7.1% relative to broadcast application on the soil surface with soil disturbance caused by band placement. Split fertigation and band placement slightly increased fruit yield, but increased marketable fruit (the total of excellent and very slightly scalded fruit) by 20.9% and 11.1% (absolute value) when compared with broadcast application of N and P and broadcast application of N and P with soil disturbance caused by band placement, respectively, and after 3 months of cold storage. No detrimental effects on fruit weight or reduction in soil amino sugar N were observed from lowering the N and P application rates by 20% with split fertigation. Overall, split fertigation and band placement of N and P can be used to replace single broadcast application on the soil surface on pear orchards to reduce fruit superficial scald during cold storage and improve the use efficiency of applied N and P in the mid-Columbia region of Oregon.