地表覆盖方式对黄土旱塬区土壤碳氮的影响

Effects of mulching patters on soil carbon and nitrogen in arid area of Loess Plateau

为了解不同覆盖方式对土壤总有机碳(SOC)、全氮(TN)、微生物量碳(MBC)和微生物量氮(MBN)的影响,旨在为该区域土壤碳氮动态变化以及旱作农田管理方式提供理论依据。基于田间定位试验,以黄土旱塬区春玉米田为研究对象,设置无覆盖对照、全生育期9 000 kg/hm2秸秆覆盖(SM)、全生育期地膜覆盖(PM)3种处理方式,结果表明:(1)与无覆盖对照相比,秸秆和地膜覆盖均显著增加土壤表层SOC、TN和MBC、MBN的含量,且秸秆覆盖处理的影响程度高于地膜覆盖处理,说明秸秆覆盖处理更加有利于土壤碳氮的累积;(2)不同覆盖方式除TN与MBC无显著相关性,其他各指标间均呈显著的正相关关系,说明土壤有机碳与全氮之间关系密切,MBC和MBN在较大程度上依赖于土壤SOC和TN的贮存量,对SOC的动态变化响应较快;(3)各处理表层土壤SOC、TN、MBC、MBN含量随土层的深入而降低。

The effects of different mulching patters on soil organic carbon, total nitrogen, microbial biomass carbon and microbial biomass nitrogen were studied to provide theoretical basis for the dynamic change of soil carbon and nitrogen, and the management of dry farmland. A positionable experiment of spring maize was conducted in Loess Plateau, which set up three different mulching patters ： without mulching treatment as control （ CK ）, straw mulching at a rate of 9 000 kg/hm2 （ SM ） and degradable plastic film mulch （ PM ） . The results showed that compared with CK, straw and plastic film mulching significantly increased the contents of SOC, TN, MBC and MBN in soil layer. The effect of SM treatment was better than PM treatment. There were significant positive correlations among different indexes （ P〈0.05 ） , except TN and MBC, which showed close relationship between soil organic carbon and total nitrogen. The storage capacity of MBC and MBN in a large extent depended on SOC and TN, which respond rapidly to SOC dynamic change. The contents of SOC, TN, MBC and MBN decreased with the decline of soil laver.