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Fig. 4. Effect of trickle irrigation (Tr), overhead sprinkler irrigation (Ov), trickle irrigation plus controlled-release fertilizer (TrF), and overhead sprinkler irrigation plus controlled-release fertilizer (OvF) on cumulative nitrate N in leachate in soil columns during a 2-yr study. Records during the experiment of precipitation and air and soil temperatures and records of percent soil moisture in overhead and trickle irrigation treatments are presented. * = significant at P 
0.05; NS = not significant.
