The upward transport of nitrate into the root zone, from N-enriched water applied through subirrigation, was monitored and its effects on potatoes were studied. The experiment was conducted in field lysimeters on the Macdonald Campus of McGill University, Canada. Potato tubers were planted in nine lysimeters, six of which were subirrigated with N-enriched water (25 μg NO{sub}3-N/ml) and the remaining three with fresh water Plastic mulch was used to simulate arid conditions in the lysimeters subirrigated with fresh water and in three of the lysimeters subirrigated with N-enriched water Soil samples collected at 0.1, 0.2, and 0.3 m depths were analyzed for available NO{sub}3-N. The results indicated that, after the initiation of subirrigation, there was a significant increase (P < 0.05) in NO{sub}3-N concentration at a depth of 0.3 m in the lysimeters subirrigated with N-enriched water In the same lysimeters, the average concentration of NO{sub}3-N in the groundwater dropped from 22.2 250L蘥 NO{sub}3-N/ml to 4.4 μg NO{sub}3-N/ml after 25 days of subirrigation. The potato tuber yield was higher in these lysimeters as compared to the control. It was concluded that nitrate in the drainage effluent can be transported upward in the root zone, thus benefiting the crop, and minimizing pollution due to untreated drainage outflow.
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