Effect of different fertilizing methods on nitrogen balance in the black soil for continuous maize production in Northeast China

To study the effect of different fertilizing methods on the characteristics of nitrogen mineralization and residual in the black soil and nitrogen balance in the continuous spring maize cultivation, a three-year field experiment was conducted to study the effect of different fertilizing methods (basal fertilizer plus topdressing based on soil mineral nitrogen test, Opt and traditional application, Tra1 and Tra2) on nitrogen (N) balance and residue in the soil at a fixed location in northeast China. The results indicated that the grain yield, biomass, and N uptake of maize in optimized N treatment (basal fertilizer plus topdressing based on soil mineral nitrogen test, Opt) were highest. In the traditional application 1 (85% basal N fertilizer + 15% seed manure, Tra1) and traditional application 2 (basal N fertilizer only, Tra2) were influenced by annual rainfall amount, the residual nitrate moved down obviously. The nitrate-N of 3060 cm and 6090 cm in the soil under Tra1 and Tra2 treatments were about two and 2.4～3.3 times greater than that of Opt treatment, respectively. The N residue in the soil was decreased significantly under Opt treatment. Nitrogen surplus in the soil sharply increased with increasing N input, and the maximum was 400.9 kg/ha. Nitrogen surplus under Tra2 treatment was the lowest, which was based mainly on residual Nmin. N application once at seeding increased significantly soil Nmin which lead to high apparent N loss. Application of all the N fertilizer at seeding lead to significant nitrate leaching into the deep soil in the condition of black soil in northeast China, and therefore threatened the environment to a large degree. Basal fertilization plus optimized topdressing based on soil mineral-nitrogen test was a promising way to increase N fertilizer utilization and reduce N loss.