Response of Wild Blueberry Yield to Spatial Variability of Soil Properties

Crop management practices within wild blueberry fields are implemented uniformly, with inadequate attention being given to substantial variations in soil properties and fruit yield. These variations emphasize the need for precise and site-specific crop management based on proper characterization and quantification of spatial soil variability. The objective of this research was to characterize and quantify the spatial patterns of variability in soil properties and fruit yield. A grid pattern of sampling points was established at each experimental site to collect soil and fruit yield samples during 2009 to 2010 at North River and Carmal sites, Nova Scotia, Canada. The soil samples were collected from 0- to 15-cm depth at each grid point. These soil samples were analyzed for soil organic matter, pH, texture, electrical conductivity, and inorganic nitrogen (N). The volumetric moisture content (theta(v)) was recorded at each grid point using time domain reflectometry. Ground conductivity readings were also recorded using dual EM conductivity meter at same selected grid points. Fruit yield was mapped using calibrated digital color photography during the crop year. The coefficient of variation of the soil properties and fruit yield suggested moderate to high variability (coefficient of variation >15%) except for soil pH. The results of correlation analysis indicated that the values for inorganic N, soil organic matter, electrical conductivity, clay, and theta(v) were generally higher in high-yielding areas and vice versa. The trend was opposite for sand and silt content, which were higher in low-yielding areas. Most of the soil properties had a large spatial variation with semivariogram range of 20 to 50 m and varied greatly within field. Kriged maps of soil properties and fruit yield also showed substantial variation within field. Characterization of spatial soil variability in wild blueberry fields would assist in planning future soil sampling in new fields showing soil and/or yield variability. The selection of soil sampling should be based on the sampling interval suggested by the variogram range (<20 m). Proper soil sampling can help in identifying yield-limiting soil properties and develop prescription maps for site-specific nutrient management to ameliorate unproductive areas and reduce environmental contamination.