Effect of N application methods on N uptake and utilization efficiency in maize - soybean relay strip intercropping system.

To investigate the effect of N application methods on N uptake and utilization efficiency in the maize - soybean relay strip intercropping system, a field experiment was conducted with three N application rates (N, 210, 270 and 310kg • hm^-2, which is considered as three N treatments, and denoted as A1, A2 and A3, respectively) and four fertilization applied distances (the distance between the fertilization dot and the narrow row corn of four treatments were 0, 15, 30,45cm, denoted as B1, B2, B3 and B4, respectively). The results showed that at the treatments of A1 and A2, the number, dry weight and the potential nitrogen fixation of nodules for each plant were higher than those of conventional N application rate ( A3 ) at the stages of R2 and R5. At the same time, the nodules nitrogenase ability of treatment B2 was more than those of other treatments. With the increasing of nitrogen application rates, the grain yield, N uptake and N use efficiency of maize and soybean increased, then dropped. The maximum values of the indices occurred at the treatment of A2. The application distance of fertilization significantly affected the yield, nutrient uptake and utilization of maize and soybean. The fertilization effect was optimal when the distance was between 15 and 30 cm. As the amount of N fertilizer decreased by 18% ( A2), the grain yield of maize, soybean and the intercropping system, N uptake of plants, N utilization efficiency and the total nitrogen content of soil improved significantly with B2 and B3 treatments, comparing with the conventional fertiliza-tion of B1 treatment, N contribution rate of soil reduced significantly. [ABSTRACT FROM AUTHOR]