水和氮调控对草场土壤微生物学特性影响研究

摘要

通过对内蒙古草场田间试验,研究水和氮调控对草场土壤微生物生物量、土壤呼吸、土壤微生物活性以及微生物群落结构的影响,试验按照裂区设计,主区为降水量(正常降水、增加降水180 mm/年),副区为氮素施用量(0、50、100、150 kg/hm2).结果表明:土壤微生物碳、氮量随施氮量增加而降低,施氮量为150 kg/hm2时最低,分别为105.23 mg/kg、13.85mg/kg;增加降水会缓解下降趋势,50 kg/hm2施氮量时数值显著提升50.6％、59.4％;随施氮量增加,土壤基础呼吸、土壤诱导呼吸逐渐降低,CAI、呼吸商逐渐升高,施氮量最大时分别下降30.95％、98.02％,升高73.63％、63.74％,增加降水后各指标均有明显提升,土壤基础呼吸、诱导呼吸增加显著;随施氮量增加,土壤DHA酶、PRO酶、Acid PME酶、Alkaline PME酶逐渐降低,增加降水会使各酶升高;细菌、真菌、丛枝菌根真菌和厌氧菌相对丰度分别在施氮量为100、100、0、150 kg/hm2时最高,增加降水后使厌氧菌、丛枝菌根真菌分别降低11.07％、增加20.59％.%Based on the field experiment in Inner Mongolia grassland,the effects of precipitation and nitrogen regulation on biomass,soil respiration,microbial activity and microbial community structure of soil microbes in grassland were studied.According to split plot design,the main area was precipitation (normal precipitation,increased precipitation 180 mm/a),split plot was the amount of nitrogen application (0 kg/hm2,50 kg/hm2,100 kg/hm2,150 kg/hm2).The results showed that the amount of soil microbial biomass carbon and nitrogen decreased with the increase of nitrogen application rate.When the amount of nitrogen application was 150 kg/hm2,the soil microbial biomass carbon and nitrogen was lowest in 105.23 mg/kg,13.85 mg/kg,respectively.The increase in precipitation eased the downward trend,when the amount of nitrogen application was 150 kg/hm2,the value significantly incresed by 50.6 ％,59.4 ％ respectively.With the increase of nitrogen application rate,the soil basal respiration and soil induced respiration decreased gradually,CAI,respiratory quotient gradually increased.When nitrogen application rate reached maximum,the value decreased by 30.95％ and 98.02％ and incresed by 73.63％ and 63.74％,respectively.The indices were increased significantly after incresing precipitation,the soil basal respiration and the induced respiration increased significantly.With the increase of nitrogen application rate,the soil DHA,PRO,PME Acld and PME Alkaline were gradually decreased,while the increase of precipitation would increased the enzyme activity.When the amount of nitrogen application was 100,100,0 and 150 kg/ hm2,the relative abundance of bacteria,fungi,arbuscular mycorrhizal fungi and anaerobic bacteria was highest,while the anaerobic bacteria and arbuscular mycorrhizal fungi decreased by 11.07 ％,increased by 20.59％ respectively after increasing precipitation.