Evaluation of water pollution from rice cultivation using Nitrogen fertilizer in North of Iran

The increase of nitrite and nitrate concentrations in surface and groundwater is a greatconcern in our lives nowadays. Nitrate and nitrite in drinking water normally originate fromagricultural operation and chemical fertilizers. Therefore, the present study aims toinvestigate the effect of nitrogen fertilizers used in rice cultivation and levels of nitrate andnitrite in farm wastewater and water quality parameters. The study was conducted in 2015using a randomized complete block design with three replications in the research farm ofGonbad Kavous University. The treatments included four levels of nitrogen (control, 37, 70and 150 kg ha with 46%urea). Urea fertilizer was applied to rice in two vegetative and earlyreproductive stages. Results showed that the effect of fertilizer on water pollution(concentration of nitrite and nitrate) is significant at the one percent level of confidence.Mean comparison of nitrogen indicated that the highest nitrate concentration (0.480 ppm)and the high nitrite (0.044 ppm) were related to treatment with high fertilizer application(150 kilograms per hectare) and the lowest nitrate concentration (0.083 ppm) and nitrite(0.014 ppm) were attributed to control treatment. Mean comparison of different stages ofsampling revealed that rice in the vegetative stage and early reproductive stage absorbedmore nitrogen while at the end of the growing period plant nitrogen uptake declined.