Effects of combined nitrogen fertilizer and nano-carbon application on yield and nitrogen use of rice grown on saline-alkali soil

To investigate the effects of combined application of nitrogen fertilizer and nano-carbon on nitrogen use of soil and rice yield, six treatments were applied as a randomized complete block design with three replications including A 1 (N 215 kg hm -2 + nano-carbon 1.194 kg hm -2 ), B 1 (N 215 kg hm -2 ), A 2 (N 150.5 kg hm -2 + nano-carbon 0.836 kg hm -2 ), B 2 (N 150.5 kg hm -2 ), A 3 (N 107.5 kg hm -2 + nano-carbon 0.597 kg hm -2 ) and B 3 (N 107.5 kg hm -2 ), respectively, to a rice cv. Changbai 10. The soil total and available N, the N accumulation, dry matter accumulation of aerial part and the yield components such as spike number, filled spike number, 1000-grain weight and yield of O. sativa were studied. The result indicated that significant differences in nitrogen use of saline-alkali soil and yield were observed among the treatments and the deliverability of soil nutrition, the nitrogen uptake of plant, dry matter accumulation and yield significantly increased after combined application of nitrogen fertilizer and nano-carbon. The nitrogen accumulation of rice of A 1 , A 2 and A 3 treatments were 13.23%, 9.57% and 38.14% higher than B 1 , B 2 and B 3 treatments, respectively; total nitrogen residues of soil of A 1 , A 2 and A 3 treatments were 6.95%, 8.48% and 9.65% lower than B 1 , B 2 and B 3 treatments, respectively; dry biomass of aerial part of A 1 , A 2 and A 3 treatments were 58%, 15.7% and 19.3% higher than B 1 , B 2 and B 3 treatments, respectively. The yield of all treatments combined application of N and nano-carbon were higher than those in treatments that only applied nitrogenous fertilizer was applied, compared to B 1 , B 2 and B 3 treatments, the yield of A 1 , A 2 and A 3 treatments were 18.36%, 8.51% and 10.19% higher, respectively. There was no significant difference between the yield of A 2 and B 1 , which indicated that the yield of combined application of 70% conventional fertilizer and nano-carbon (N 150.5 kg hm -2 and nano-carbon 0.836 kg hm -2 ) was equal to that with supplied 100% conventional fertilizer (N 215 kg hm -2 ). This indicated that the utilization rate of nitrogen fertilizer increased after combined application of nano-carbon, which can save the N fertilizer in production practice. Therefore, combined treatment is suitable to application and dissemination in soda saline-alkali soil in the agriculture.