施氮对西北荒漠灌区紫花苜蓿土壤理化性质及微生物数量的影响

Effect of nitrogen application on soil physicochemicalproperty and microbial quantity of alfalfa in desertirrigation area of Northwest China

摘要:

以“甘农3号”紫花苜蓿为材料,设5个氮水平(0、51.75、103.5、155.25、207 kg/hm2),通过2年(2016年、2017年)田间试验,探究不同施氮处理对紫花苜蓿土壤全氮、有机质、碱解氮含量等土壤的养分、pH值及土壤微生物数量的影响,并对土壤养分与微生物数量进行相关性分析。结果表明:施氮可以提高紫花苜蓿土壤有机质、碱解氮含量,降低土壤pH值。当施氮量为51.75、103.5 kg/hm2时,紫花苜蓿土壤有机质、碱解氮含量最高,2016年和2017年分别为15.7 g/kg、17.89 g/kg和41.8 mg/kg、65.2 mg/kg,同时土壤微生物(细菌、真菌和放线菌)的数量最多。土壤全氮、碱解氮、有机质含量及pH值均与真菌、细菌和放线菌数量成正相关关系,其中土壤有机质含量与真菌和细菌数量呈极显著正相关(P＜0.01),与放线菌数量呈显著正相关(P＜0.05),pH值与放线菌数量呈显著正相关(P＜0.05)。因此,当施氮量为51.75、103.5 kg/hm2时,可以有效改善土壤理化性质,提高土壤微生物数量。

Abstract:

In order to explore the effect of nitrogen application on the number of alfalfa soil microorganisms under the condition of low soil nutrients and high salinization in desert irrigation area of Northwest China,alfalfa ‘Gannong 3’ was used as material and 5 nitrogen levels (0 kg/hm2,51.75 kg/hm2,103.5 kg/hm2,155.25 kg/hm2,and 207 kg/hm2) were tested in the field for two years (2016 and 2017).The effects of different nitrogen application treatments on soil total nitrogen,organic matter,pH value,alkali-hydrolyzable nitrogen content of alfalfa,and the number of soil microorganisms were studied,and the correlation between soil nutrients and microorganisms was analyzed.The results showed that nitrogen application could increase the content of organic matter and alkali-hydrolyzable nitrogen in alfalfa soil and decrease the pH value of soil.In this study,when the amount of nitrogen application was 51.75 kg/hm2 and 103.5 kg/hm2,the contents of organic matter and alkali-hydrolyzable nitrogen in alfalfa soil were the highest,which was 15.7 g/kg、17.89 g/kg and 41.8 mg/kg、65.2 mg/kg in two years,respectively,and the number of soil microorganisms (bacteria,fungi and actinomycetes) in alfalfa soil was the highest.Soil total nitrogen,alkali-hydrolyzable nitrogen,organic matter,and pH value were positively correlated with the number of fungi,bacteria,and actinomycetes,and soil organic matter showed an extremely significant positive correlation with fungi and bacteria (P＜0.01),a significant positive correlation with actinomycetes (P＜0.05),and PH was significantly positively correlated with actinomycetes (P＜0.05).Therefore,when the amount of nitrogen application is 51.75 kg/hm2 and 103.5 kg/hm2,it can effectively improve the physical and chemical properties of soil and increase the number of soil microorganisms.