Effect of nitrogen application on soil nitrogen content, root growth and nitrogen uptake of a meadow in the Wugong Mountains

A meadow in the Wugong Mountains was selected as the study site for an investigation into the effects of nitrogen application (N0: 0 kg·ha-1, N1: 75 kg·ha-1, N2: 150 kg·ha-1, N3: 300 kg·ha-1.) on soil nitrogen content, root growth and nitrogen uptake by the meadow using a randomized block experiment design. The results showed that the content of available N in the soil increased with the increase in nitrogen (P<0.05). In all treatments, the available N content first increased and then decreased with time, with the lowest values appearing from July to September (N0:111.7 mg·kg-1, N1:140.6 mg·kg-1, N2:162.7 mg·kg-1, N3:1 169.0 mg·kg-1). The results showed a striking difference (P<0.05) between the treatments N0, N1 and N2. The root biomass density of the treatments in the 0-20 cm soil layer from high to low was N3(10.27 mg·cm-3) >N2(10.02 mg·cm-3) >N1(8.0 mg·cm-3) >N0 (6.28 mg·cm-3), and the root length density was N3 (20.1 cm·cm-3)>N2 (20.09 cm·cm-3) >N1 (17.2 cm·cm-3) >N0 (14.3 cm·cm-3). The N accumulation of the roots (N0:13.7 kg·ha-1, N1:23.3 kg·ha-1, N2:31.2 kg·ha-1) also increased significantly with the increase in nitrogen application in the range of N0-N2 (0-150 kg·ha-1) (P<0.05) in the 0-20 cm soil layer. Therefore, more care should be taken to prevent the environmental pollution and waste of resources caused by N loss when nitrogen fertilizer is applied to meadows in the Wugong Mountains.