施氮对武功山山地草甸土壤氮素含量、根系生长及氮素吸收的影响

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

本研究以武功山草甸为研究对象,采用随机区组试验设计,研究不同施氮水平(N0:不施氮;N_1:施氮量75kg·hm-2;N_2:施氮量150kg·hm-2;N_3:施氮量300kg·hm-2)下草甸土壤氮素时空变化规律和草甸植被根系形态特征及其对氮素吸收利用的影响。结果表明:土壤碱解氮含量随着施氮量的增加而增加(P<0.05),各施氮处理土壤碱解氮含量随时间推移呈先升高后降低的趋势,并在7-9月间平均值降到最低(N0:111.7 mg·kg^(-1);N_1:140.6mg·kg^(-1);N_2:162.7mg·kg^(-1);N_3:1 169.0mg·kg^(-1));各处理0-20cm土层根系生物量密度由高到低依次为N_3(10.27mg·cm^(-3))>N_2(10.02mg·cm^(-3))>N_1(8.0mg·cm^(-3))>N0(6.28mg·cm^(-3)),根长密度由高到低依次为N_3(20.1cm·cm^(-3))>N_2(20.09cm·cm^(-3))>N_1(17.2cm·cm^(-3))>N0(14.3cm·cm^(-3)),其中N0、N_1和N_2这3个处理差异显著(P<0.05);在0-150kg·hm-2的施氮范围内,根系对氮素的积累(N0:13.7kg·hm-2;N_1:23.3kg·hm-2;N_2:31.2kg·hm-2)随着施氮量的增加而显著增加(P<0.05)。因此,在武功山草甸施用氮肥时应注意其氮肥施用量(推荐施氮范围为0-150kg·hm-2),避免氮素流失引起环境污染及资源浪费。

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.