摘要
[目的]探究根系分泌物中糖类、有机酸和酚酸及其混合作用对森林土壤微生态和碳氮矿化的影响,加深对根际过程的认识。[方法]以黄土丘陵区人工油松林土壤为研究对象,通过室内培养的方法,设置无菌蒸馏水(CK),葡萄糖(G),草酸(A),对羟基苯甲酸(H),葡萄糖+草酸(GA),葡萄糖+对羟基苯甲酸(GH),草酸+对羟基苯甲酸(AH)以及葡萄糖+草酸+对羟基苯甲酸(GAH)共8种分泌物处理,研究了分泌物连续添加84 d内土壤养分、微生物量和酶活性以及碳氮矿化速率的变化。[结果](1)不同分泌物添加处理均提高了土壤速效磷(AP)、硝态氮(NO_(3)^(-)-N)和铵态氮(NH_(4)^(+)-N)含量和微生物量。且A和H的促进作用总体强于G,混合添加对NH_(4)^(+)-N,AP和微生物量碳(MBC)的促进作用强于单独添加。(2)分泌物添加主要在0~56 d内提高了土壤酶活性,84 d时促进作用下降甚至转为抑制。G添加在0~28 d对β-葡糖苷酶(CBH),纤维素二糖水解酶和N-乙酰-D-葡萄糖胺酶活性的促进作用显著强于A和H,其促进作用随培养的进行逐渐降低,而A和H的促进增加。与单独添加相比,分泌物混合添加未明显提高土壤酶活性,甚至降低了酶活性。(3)分泌物添加在0~14 d提高了土壤硝化和氨化速率。其中A,H和GAH处理中硝化速率最高,G,A H和GAH处理中氨化速率最高。微生物量磷(MBP),CBH和AP是影响土壤硝化和氨化速率的最主要因素。(4)各分泌物添加均提高了土壤总有机碳矿化,其促进作用随着培养的进行逐渐增强。GH和AH处理中CO_(2)累积释放量最高,与CK相比分别提高42.8%和40.8%,MBP,NO_(3)^(-)-N,NH_(4)^(+)-N和CBH是影响CO_(2)释放的最主要因素。[结论]分泌物添加前期主要提高土壤酶活性和氮矿化,后期加剧了CO_(2)释放。草酸和对羟基苯甲酸以及混合添加比葡萄糖更有助于提高土壤速效养分和微生物量,进而促进土壤碳氮循环。
[Objective]This study aims to explore the effects of carbohydrates,organic acids,and phenolic acids in root exudates,and their combined impact on soil microorganisms and carbon(C)and nitrogen(N)mineralization in forests,thereby deepening the understanding of rhizosphere processes.[Methods]Soil from artificial Pinus tabuliformis forests in loess hilly regions was taken as the research object.Soil samples were collected and laboratory incubation experiments were conducted with eight treatments of exudates:sterile distilled water(CK),glucose(G),oxalic acid(A),p-hydroxybenzoic acid(H),glucose+oxalic acid(GA),glucose+p-hydroxybenzoic acid(GH),oxalic acid+p-hydroxybenzoic acid(AH),and glucose+oxalic acid+p-hydroxybenzoic acid(GAH).The changes in soil nutrients,microbial biomass,enzyme activities,and carbon and nitrogen mineralization rates were measured during continuous exudate addition over 84 days.[Results](1)The concentrations of available phosphorus(AP),nitrate nitrogen(NO_(3)^(-)-N),ammonium nitrogen(NH_(4)^(+)-N),and microbial biomass were increased by all treatments of exudate addition.The promoting effects of A and H were generally stronger than those of G.The mixed addition of exudates had a greater effect on NH_(4)^(+)-N,AP,and microbial biomass carbon(MBC)compared with the addition of single components.(2)Exudate addition increased soil enzyme activities within 0~56 days,and the promoting effect diminished or even shifted to inhibition by 84 days.During 0~28 days,G showed stronger promoting effects on Beta-Glucosidase,Cellobiohydrolase(CBH),and N-Acetyl-D-Glucosaminidase activities than A and H,but its effect gradually decreased,while the effects of A and H increased.Compared with single addition treatments,mixed addition of exudates did not significantly enhance enzyme activity and even reduced it.(3)Exudates addition during 0~14 days increased soil nitrification and ammonification rates.Specifically,the highest nitrification rates were found in the A,H,and GAH treatments,while the highest ammonification rates were found in the G,AH,and GAH treatments.Microbial biomass phosphorus(MBP),CBH,and AP were the most important factors influencing soil nitrification and ammonification.(4)The addition of each exudate increased soil organic carbon(SOC)mineralization,with greater promoting effects observed over the incubation periods.The cumulative CO_(2) emissions were highest in the GH and AH treatments,increasing by 42.8%and 40.8%,respectively,compared to CK.MBP,NO_(3)^(-)-N,NH_(4)^(+)-N,and CBH were identified as the most important factors influencing CO_(2) emission.[Conclusion]The addition of exudates primarily enhances soil enzyme activity and nitrogen mineralization during the early stage,and intensify carbon mineralization during the later stage.Oxalic acid,p-hydroxybenzoic acid,and their mixed addition demonstrate greater efficacy than glucose in improving soil available nutrients and microbial biomass,thereby promoting soil carbon and nitrogen cycling processes.
作者
王慧玲
马辉珍
王国梁
Wang Huiling;Ma Huizhen;Wang Guoliang(College of Soil and Water Conservation Science and Engineering,Northwest A&F University,Yangling,Shaanxi 712100,China;Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling,Shaanxi 712100,China)
出处
《水土保持研究》
北大核心
2025年第6期113-122,共10页
Research of Soil and Water Conservation
基金
国家自然科学基金(42077456)
国家自然科学基金专项类项目(42041005-3B)。
关键词
根系分泌物
土壤养分
酶活性
有机碳矿化
有机氮矿化
root exudates
soil nutrients
enzyme activity
soil organic carbon mineralization
nitrogen mineralization
