Improvement of nitrogen fertilizer dressing in deep soil on absorption, allocation and utilization of ¹⁵N of maize

Objectives Using the ¹⁵N tracing technology, we analyzed effects of different nitrogen topdressing methods on absorption, distribution and utilization of nitrogen of maize in cold zone, and offered theoretical assistance to the reasonable fertilization of the maize.

Methods Maize cultivar Demeiya 3 was used as material in a field pot experiment, the field experiment was set with the different nitrogen topdressing methods, namely, N0 (without N), once surface topdressing (S1), once deep topdressing (D1) and twice deep topdressing (D2). The dry mater biomass and N use efficiencies were analyzed.

Results Deep dressing of nitrogen were more effective in the biomass accumulation than surface dressing (S1), and the effect of the D2 was better than that of the D1 treatment (P < 0.05). The N contents in all the tested organs, except in stem, in the treatment D2 were significantly higher than D1 and S1 (P < 0.05), and the N accumulation in D2 were significantly higher than in D1 and S1 in all the organs but for stem and shaft (P < 0.05);The labeling ¹⁵N abundance in D2 and D1 are higher than in S1 (P < 0.05) as well, but for axis1 (P < 0.05);The distribution of ¹⁵N in roots and seeds were significantly higher in D2 than in D1 and S1, but those in the leaves and axis were higher in S1 than in D1 and D2;Compared with S1, The use efficiency of ¹⁵N in D2, and D1 were improved by 26.0% and 14.9% respectively (P < 0.05), the residue of ¹⁵N decreased by 2.1% (P < 0.05) and 1.2% respectively, and the loss of nitrogen in D2 and D1 were reduced by 23.9% and 12.9% respectively, the contribution of N fertilizer on the increase of nuse efficiency were improved 3.6% and 0.6% in D2 and D1 respectively (P < 0.05).

Conclusions Twice deep dressing of nitrogen fertilizer performs satisfactory in increasing the absorption and distribution of N in different organs of maize, and increase the usage efficiency of nitrogen and the contribution rate of nitrogen fertilizer to the yield, reducing residues and losses of N in soil. Therefore the measurement should be recommended in the cold area tested.