长期施肥黄土旱塬农田土壤⁃微生物⁃植物系统碳氮磷生态化学计量特征

Ecological stoichiometric characteristics of soil⁃microorganism⁃plant system in the Loess upland under long⁃term fertilization

探讨长期不同施肥制度对农田土壤、植物生态系统的碳(C)、氮(N)、磷(P)含量及其生态化学计量比的影响,可为揭示该系统能量平衡和养分循环,实现农业生态系统元素平衡及可持续发展提供参考意义。以位于黄土高原半干旱地区的长武国家黄土高原农业生态实验站长期施肥试验为研究对象,选取不施肥(CK)、单施氮肥(N)、单施磷肥(P)、施氮磷肥(NP)、单施有机肥(M)、氮肥配施有机肥(NM)、磷肥配施有机肥(PM)、氮磷肥配施有机肥(NPM)8个处理,分析了黄土旱塬典型农田土壤⁃微生物⁃植物生态系统中C、N、P含量及其生态化学计量变化规律。研究结果表明:1)长期单施有机肥和化肥配施有机肥处理可显著提高土壤和有机质C、N、P含量。2)氮、磷肥的输入显著降低了土壤和小麦C∶N、N∶P,施P显著降低了有机态C∶P和小麦C∶P;有机肥配施对微生物生物量和小麦C∶N∶P的影响更为明显。3)长期有机肥配施条件下土壤养分和小麦化学计量比存在较强的相关关系。微生物生物量碳与有机C、N、P呈显著正相关,土壤微生物生物量氮与土壤N、P总量呈显著正相关,微生物生物量磷与土壤C、N、P总量含量呈显著负相关;植株碳含量与微生物生物量氮呈显著正相关,植物磷含量与土壤有机磷呈显著正相关。黄土区农田生态系统土壤TC∶TP与TC∶TN,TN∶TP呈正相关,土壤TN∶TP与有机碳和有机磷比呈正相关,植物植株C∶N与BC∶BP、BN∶BP呈正相关。长期施肥明显改变了土壤和植物C、N、P含量及化学计量比。氮肥配施有机肥可明显提高微生物对土壤碳素的转化分解,导致有机质和微生物量的化学计量比发生变化,进而提高作物对土壤碳素的固定能力,增强植株对外源养分的输入。

To explore the effects of different fertilization systems on carbon,nitrogen and phosphorus contents and ecological stoichiometric ratio of farmland soil and plant ecosystem in a long time can provide reference for revealing the energy balance and nutrient cycle of the system and realizing the balance and sustainable development of agricultural ecosystem elements.In this study,the long⁃term fertilization experiment at the Loess Plateau agricultural ecology experimental station of Changwu,located in the semi⁃arid region of the Loess Plateau,was taken as the research object.No fertilization(CK),single application of nitrogen(N),single application of phosphate(P),single application of nitrogen and phosphate(NP),single application of organic fertilizer(M),combined application of nitrogen and organic fertilizer(NM),application of phosphate and organic fertilizer(PM),and combined application of nitrogen and phosphate and organic fertillizer were selected.The contents of C,N and P in soil,microbe and plant in typical agricultural ecosystem of the Loess Plateau were analyzed,and the change rule of stoichiometry and its influencing factors were analyzed.The results showed that:(I)compared with CK,long⁃term single application of organic fertilizer and fertilizer combined with organic fertilizer treatment could significantly improve the carbon,nitrogen and phosphorus content of soil and organic matter.(II)With the input of exogenous nitrogen and phosphate fertilizer,compared with CK treatment,N and P treatment significantly reduced soil and wheat C∶N and N∶P,respectively,and P treatment significantly reduced organic matter and wheat C∶P.However,the effect of organic fertilizer combination on microbial biomass and wheat C∶N∶P was more obvious.(III)There was a significant correlation between soil nutrients and the stoichiometric ratio of wheat under the condition of long⁃term organic fertilizer application,compared with no fertilization.The results showed that long⁃term fertilization significantly changed soil carbon,nitrogen and phosphorus contents and stoichiometric ratio,and fertilizer combined with organic fertilizer could significantly improve soil fertility in the xeroxic farmland of loess,resulting in the change of stoichiometric ratio of organic matter and microbial biomass,which had a significant impact on the stoichiometric ratio of wheat plants.