The development of site-specific agriculture has increased the need for knowledge regarding within-field variability in factors such as soil/plant characteristics and topography that influence wild blueberry (Vaccinium angustifolium) production. Surface soil properties are the first type of information most frequently used by blueberry producers in developing management plans. Topographic features are not yet routinely used to guide within-field management. The majority of blueberry fields in eastern Canada have gentle to severe topography. An automated slope measurement and mapping system (SMMS) consisting of low-cost accelerometers used as tilt sensors, differential global positioning system (DGPS), and laptop and custom software was developed. The SMMS was mounted on an all-terrain vehicle for real-time slope measurement and mapping. Six commercial wild blueberry fields were surveyed in central Nova Scotia to evaluate the performance of SMMS. The automatically sensed slopes (SS) were also compared with manually measured slopes (MS) at 20 randomly selected points in each field to examine the accuracy of SMMS. The SMMS measured slope reliably in the selected fields with root mean square error ranging from 0.12 to 0.56 degrees and correlations of SS with MS of R2 = 0.95 to 0.99. The selected fields had substantial variation in slope (ranging from 0.8 to 31.0 degrees). Therefore, the use of low-cost and reliable accelerometers with a DGPS is a better option than expensive real-time kinematic DGPS for developing cost-effective SMMS to quantify and map slopes (real-time) for planning site-specific management practices in commercial fields. The SS maps or real-time SMMS could also be used to adjust vehicle speed at particularly steep slopes.
Qamar Uz Zaman, Arnold Walter Schumann and David Charles Percival
Rizwan Maqbool, David Percival, Qamar Zaman, Tess Astatkie, Sina Adl and Deborah Buszard
The study examined the main and interactive effects of soil-applied fertilizers [nitrogen (N), phosphorus (P), and potassium (K)] from a 12-year (six production cycles) field experiment conducted at Kemptown, Nova Scotia (Canada). It also recommends the optimum rate for improved growth and harvestable yield of wild blueberry (Vaccinium angustifolium Ait.). The fertilizers were applied in a single application at the onset of shoot emergence in early spring of each sprout year at rates of 0, 12, 30, 48, and 60 kg·ha−1 N using urea (2000 only) or ammonium sulfate, 0, 18, 45, 78, and 90 kg·ha−1 P using triple super phosphate, 0, 12, 30, 48, and 60 kg·ha−1 K using potassium chloride. Response surface analysis of the data indicated that 35 kg·ha−1 N, 40 kg·ha−1 P, and 30 kg·ha−1 K were optimum for fruit production and maintaining stem lengths <20 cm, and resulted in an average of 54% more floral buds, 25% more berries per stem, and 13% greater yield than previous recommend rates of 20 kg·ha−1 N, 10 kg·ha−1 P, and 15 kg·ha−1 K. The higher fertilizers rates cost an extra $80/ha but increased net profits by $490/ha. Findings of this study could contribute toward better farm profitability in areas with similar growing conditions. They also suggest that modifications to existing fertilizer rates be made for Central Nova Scotia wild blueberry.