不同覆盖措施对塿土碳氮及水分的影响

通过田间试验,研究了陕西关中塿土区地膜覆盖和秸秆覆盖对表层土壤有机碳、全氮和微生物量碳氮,以及0~200 cm土壤剖面水分及硝态氮分布的影响。结果表明:与不覆盖(NM)相比,白色全膜覆盖(WF)、黑色全膜覆盖(BF)和秸秆覆盖(SM)的表层土壤有机碳分别降低了19.8%、26.3%和20.9%,土壤全氮也分别降低了4.8%、9.6%和10.6%。与NM相比,覆盖处理(WF、BF和SM)可以提高表层(0~20 cm)土壤硝态氮的含量,增加0~40 cm土层的硝态氮累积量(BF的差异不显著),降低40~120 cm土层的硝态氮累积量,但120~200 cm土层的硝态氮累积量差异不显著。SM和BF显著降低0~200 cm土层的硝态氮总累积量,而WF没有显著差异。与NM相比,地膜覆盖(WF和BF)和秸秆覆盖(SM)均可以提高表层0~40 cm土壤水分含量和储水量,但SM的效果低于地膜覆盖;WF可以降低深层土壤水分含量和储水量,而SM和BF与NM无显著差异。0~200 cm土层的总储水量,SM显著高于NM,而地膜覆盖则与NM无显著差异。各覆盖处理均显著降低了表层土壤微生物碳(MBC)和微生物氮(MBN)的含量,与NM相比,MBC分别降低了27.4%、55.4%和66.5%,MBN分别降低了4.6%、4.8%和6.8%。地膜覆盖(WF和BF)和秸秆覆盖(SM)均能够加速土壤有机碳的矿化分解,降低土壤微生物,减少土壤硝态氮的深层淋溶,其对塿土碳氮和水分的长期影响值得进一步研究关注。

Effect of Different Mulching on Soil Carbon,Nitrogen and Moisture Contents in Eum-Orthric Anthrosols

Field experiments were carried out to research the effects of plastic film mulching and straw mulching on topsoil total nitrogen,soil organic carbon,soil microbial biomass carbon (SMBC) and nitrogen (SMBN),soil moisture and the NO3--N distribution and accumulation of soil profiles at 0-200 cm depths in Eum-Orthric Anthrosols in Guanzhong region of Shaanxi Province.The results showed that,compared with the situation without mulching (NM),soil organic carbon contents under white plastic film mulching (WF),black plastic film mulching (BF) and straw mulching (SM) were reduced by 19.8％,26.3％ and 20.9％,and the soil total nitrogen contents were reduced by 4.8％,9.6％ and 10.6％,respectively.All mulching measures could increase the content of NO3--N in topsoil and the accumulation of NO3--N in soil layer 0-40 cm deep,and also could significantly decrease the accumulation of NO3--N in soil layer 40-120 cm deep,however,the effects were insignificant in soil layer 120-200 cm deep.SM and BF could decrease the accumulation of NO3--N in soil layer 0-200 cm deep,but the effect of WF was not significant.Compared with NM,all mulching measures (WF,BF and SM)could increase the soil moisture content and the accumulation of soil water storage in soil layer 0-40 cm deep,in which the effect of SM was lower than that of plastic film mulching.WF could decrease soil moisture content and soil water storage in deeper soil layer,but the effects of SM and BF were insignificant.In soil layer 0-200 cm deep,soil water storage under SM was higher than that under plastic film mulching and NM,while there was no significant difference between plastic film mulching and NM.WF,BF and SM could decrease SMBC and SMBN in topsoil,of which SMBC was decreased by 27.4％,55.4％ and 66.5％,and SMBN by 4.6％,4.8％ and 6.8％,respectively.In conclusion,WF,BF and SM could be used to accelerate the decomposition of soil organic carbon,and to decrease the topsoil microbial biomass,accumulation of soil NO3--N and risk of leaching to deeper soil.Long-term effect of plastic film mulching and straw mulching on the contents of soil carbon,nitrogen and moisture needs to be further researched and paid great attention to in Eum-Orthric Anthrosols.