地表覆盖对黄土高原土壤有机碳及其组分的影响

摘要

基于中国科学院长武黄土高原农业生态实验站2008年开始田间定位试验资料，分析研究秸秆覆盖与地膜覆盖对黄土高原土壤有机碳（SOC）及其组分的影响，试验包括5个处理：对照不覆盖（CK）、作物生育期9000 kg ·hm-2秸秆覆盖（M1）、作物生育期4500 kg·hm-2秸秆覆盖（M2）、夏闲秸秆覆盖（SF）、作物生育期地膜覆盖（PM）。2010（干旱年）、2012（丰水年）两次测定结果表明：0～30 cm土层平均，与CK相比，2012年土壤有机碳（SOC）含量M1处理提高了7．4％，潜在矿化碳（PCM）含量M1、M2、SF处理分别提高了37．8％、23．9％、7．2％，微生物量碳（MBC）含量M1和M2处理分别提高了59．9％和42．3％，碳库管理指数（CMI）M1、M2、SF 处理分别提高了53．1％、35．6％、13．9％；2010年M1处理CMI较CK提高了16．1％（P＜0．05），其余处理土壤有机碳各指标与CK差异两年均不显著。不同覆盖方式对表层土壤有机碳及各项指标影响较大，随土层加深影响减弱，其中秸秆覆盖4年后碳库管理指数均有显著提高。两种活性有机碳的相对含量与其各自绝对含量的变化基本一致，且有机碳各指标间显著相关。综合来看，高量秸秆覆盖能够提高表层土壤有机碳及其组分含量，地膜覆盖对土壤有机碳及其组分积累影响不大。%A winter wheat field experiment was conducted to detect the effect of soil surface mulching on soil organic carbon (SOC)and its active fractions .Five treatments were included as control treatment (CK),straw mulching at a rate of 9 000 kg·hm-2(M1)and 4 500 kg·hm-2(M2)and plastic film mulching(PM)during growing season,and straw mulching during summer fallow(SF).The results showed that averaged across 0~30 cm soil layer,compared with CK, treatment M1 significantly increased soil organic carbon by 7 .4%,treatment M1,M2 and SF increased potential carbon mineralization by 37 .8%、23 .9% and 7 .2% significantly,treatment M1 and M2 significantly increased microbial biomass carbon by 59 .9%and 42 .3%,treatment M1、M2 and SF significantly increased carbon management index by 53.1%、35.6%and 13.9%in 2012,respectively.Treatment M1 increased carbon management index by 16.1% in 2010 significantly,compared with CK.Other treatments had no significant impact on soil organic carbon and its index was found when compared with CK .Different soil surface mulching have great influence on soil organic carbon and its in-dex,and decreased as the soil layer deepen .The carbon management index increased significantly after 4 years of experi-ment .The proportion of PCM and MBC in SOC showed the same trend with the contents of PCM and MBC,soil organic carbon and its index significantly related with each other .In general,Treatment M1 can increase soil organic carbon and its active fractions,and the plastic film mulching has less effect to soil organic carbon accumulation .