Effect of Split Fertilization on Subsurface Water Quality in Wild Blueberry Fields

Abstract. The majority of wild blueberry ( Ait.) fields are situated in acidic soils, having poor water holding capacities, weed patches, gentle to severe topography, and substantial proportion of bare spots, which emphasize the need for variable rate split (VRS) fertilization. Two commercial wild blueberry sites were selected in Nova Scotia, Canada to evaluate the impact of VRS fertilization on subsurface water contamination. The sites were divided into three sections [VRS section, uniform rate split (URS) section, and uniform rate (UR) section]. Prescription maps were generated with ArcGIS 10.1 software based on slope variation for VRS fertilization. Fertilization was performed based on the prescription maps using variable rate (VR) spreader. Fifty-four lysimeters were installed in VRS, URS, and UR treatment sections to collect subsurface water samples. Subsurface water samples were collected after every heavy rainfall event (>15 mm), and were analyzed for nitrate nitrogen (NO₃^--N) and ammonium nitrogen (NH₄⁺-N) concentrations. Leaf samples were collected from each fertilizer treatment and analyzed for macro and micro nutrients. Results suggested that the VRS treatment significantly decreased (p < 0.05) NO₃^--N and NH₄⁺-N concentrations in subsurface water samples when compared to URS and UR treatments. Overall for the Cooper site, mean NO₃^--N leaching under the VRS treatment section were 45% and 47% lower as compared to the URS and UR treatment sections, respectively. However, mean values of NH₄⁺-N concentration under the VRS treatment section of the North River site were 38% and 45% lower as compared to the URS and UR treatment sections, respectively. Results revealed that the VRS treatment did not have any negative effect on leaf nutrient concentrations. The VRS fertilization saved almost 40% in this study. Results demonstrated that the VRS fertilization in wild blueberry fields can increase fertilizer use efficiency and reduce water contamination via subsurface leaching.