NO - 3 N content of
groundwater in fields and wells at Tianfu village o f
Chengdu plain was monitored by using NO -
3 N electrode method for more tha n one y ear. Results showed that: a. NO - 3 N concentration of
groundwater in field s in wi nter and spring was higher than that in summer and autumn. The former ranged fr o m 0.36 to 2.62 mg L -1 with an average of 2.59 mg L -1 , and the co rresponding figu re for the latter was 0.84～5.48 mg L -1 and 1.10 mg L -1 , respecti vely. b. Rate o f applied N in wheat cropping season greatly affected NO - 3 N concentration of gr oundwater in the fields of subsequent rice cropping season. The NO - 3 N con centra tion of groundwater averaged 17.9 mg L -1 when N application rate was 375 kg hm -2 , and the average of NO - 3 N concentration was only 1.3 mg L -1 when 1 50 kg hm -2 w as applied. c. NO - 3 N in 3 wells was in the range of 0.14～16.5 mg L -1 with the mean value of 2.54, 3.60, and 6.52 mg L -1 , respectively, higher than th e average (1.81 mg L -1 ) of NO - 3 N concentration of irrigation water in the re gion. d. Level of groundwater was not correlated to NO - 3 N content of wells.