Impact of Variable Rate Fertilization on Wild Blueberry Plant Growth and Fruit Yield

Abstract

Abstract. Variable rate (VR) fertilizer application has the potential to improve fertilizer use efficiency, reduce cost of production, and reduce environmental impacts. Two wild blueberry fields were selected in central Nova Scotia to examine the effect of VR fertilization on plant growth and fruit yield as compared to uniform fertilization. The field boundaries, weeds, and bare spots were mapped using real-time kinematics global positioning system (RTK-GPS). The variation in slope was mapped and management zones were delineated. Both fields were divided into two sections (VR and uniform). The GPS-guided prescription maps were generated in ArcGIS 9.3 for VR treatment sections. Three fertilization rates 200, 150, and 100 kg ha -1 were applied in Z1, Z2, and Z3, respectively, with a VR fertilizer spreader. The bare spots and weeds were mapped and classified as a separate class in the prescription maps and zero rate was allocated. For comparison, growers uniform fertilizer rate of 200 kg ha -1 was applied in uniform treatment section of both fields. Soil samples were taken from selected sampling points from each field before and after the fertilization, and soil properties and levels of soil nutrients were determined. Plant growth parameters and fruit yield were also collected from selected points in each field. Plants in uniform treatment sections were taller than VR treatment sections in low lying areas. Plant density, number of branches, and number of buds were non-significantly affected with fertilizer treatments. Plant growth parameters were significantly correlated with soil properties and soil nutrients in both VR and uniform treatments. The fruit yields in VR treatment sections were non-significantly different than uniform treatment section, although mean fruit yield was higher in VR section. VR fertilization saved 39% and 41% fertilizer in Fields 1 and 2, respectively. Results of this study suggested that VR fertilization could increase fruit yield and reduce fertilizer usage in wild blueberry fields.