Environmental Impact of VRTs
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Introduction
Non-point-source agricultural pollution from crop nutrients can be mitigated by improving fertilizer use efficiency. Wild blueberry producers are currently fertilizing their fields uniformly without considering the substantial variations in topographic features. Uniform management might increase cost of production, yield reduction and it may also result in environmental contamination. The transport of nitrogen (N) fertilizer from agricultural soils to groundwater through leaching is of environmental concern and a potential risk to human health. Most of the N is leached in nitrate-nitrogen (NO3--N) form. Wild blueberry fields have gentle to severe topography with many bare spots, weeds and grasses. Nutrients accumulation in low lying areas with surface runoff can contaminate groundwater. Therefore, variable rate (VR) fertilization in wild blueberry fields based on topographic features could improve farm profitability and fertilizer use efficiency, and also can protect environment by reducing nutrient leaching.
Objectives
Several wild blueberry fields were selected in central Nova Scotia to evaluate the effects of variable rate fertilization on the ground water quality. Slope and elevation data were collected and maps were generated in Arc GIS 9.3, and then overlaid to generate a three management zone map. Three fertilizer rates (200,150 and 100 kg ha-1) were applied with a VR fertilizer spreader according to a prescription map developed from overlaid map, and also no fertilizer was applied in bare spots. For comparison, half of the field received growers uniform fertilizer rate of 200 kg ha-. Soil leachate samples were collected with suction lysimeters at 40cm depth below soil surface. The leachate samples collected after every heavy rainfall were analyzed for nitrate nitrogen (NO-3-N), and ammonium nitrogen (NH+4-N) concentrations. Variable rate fertilizer application used 42% less fertilizer than standard uniform fertilization and also resulted in protection of the environment by reducing the leaching of nutrients into ground water.
Researchers
Dr. Qamar Zaman, Associate Professor, Engineering Department, NSAC
Shoaib Saleem (Graduate Student)
Aitazaz Farooque (Graduate Student)
Partners
This research was funded by Oxford Frozen Foods Limited, Agri-Futures (ACAAF) Nova Scotia, Wild Blueberry Producers Association of Nova Scotia and Department of Agriculture Technology Development Program, Canadian Foundation for Innovation, NS Growing Forward, Department of Agriculture.
