Effect of N fertilizer types on NO and NO emissions under drip fertigation from an agricultural field in the North China Plain.

NO and NO emissions from a winter wheat-summer maize rotation field in the North China Plain were comparably investigated under three different treatments: 1) flood irrigation (A-Flood treatment) plus fertilization of NHCl, 2) drip fertigation (A-Drip treatment) plus fertilization of NHCl and 3) drip fertigation (AN-Drip treatment) plus fertilization of a mixture of Ca(NO) and NHCl. The annual NO cumulative emissions from the A-Drip treatment and the A-Flood treatment were almost identical, whereas it from the AN-Drip treatment was significantly lower (33%) than that from the A-Flood treatment. Compared with the A-Flood treatment, the annual NO cumulative emission from the A-Drip treatment was significantly increased by 140% but it from the AN-Drip treatment was only slightly increased by 14%. Compared with drip fertigation with NHCl, drip fertigation with the mixture of Ca(NO) and NHCl significantly reduced the cumulative emissions of NO (31%) and NO (52%) from the nitrification dominated fields by decreasing the supplement of NH substrate. Among the three fertilization treatments, the yields of the maize from the A-Drip and AN-Drip treatments were significantly increased, while the yields of the wheat were almost the same. Considering the benefit of increasing yields and reducing N fertilizer and water input, the application of nitrate-based fertilizer instead of partial ammonium-based fertilizer through drip fertigation could be a promising method for keeping agronomic productivity and environmental sustainability.