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

Abstract

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