不同量秸秆覆盖还田对土壤活性有机碳及碳库管理指数的影响

为探明渭北旱塬不同秸秆覆盖量对春玉米田土壤活性有机碳(LOC)、 碳库管理指数(CMI)和作物产量的影响,于2007—2010年在陕西合阳县旱农试验站进行定位试验,以不覆盖为对照(CK),设置了3个水平秸秆覆盖量处理:4 500 kg/hm²(S1)、 9 000 kg/hm²(S2)和13 500 kg/hm²(S3)。结果表明,0~20 cm土层,与CK相比,S1、 S2和S3总有机碳(TOC)质量分数分别提高5.08%、 14.12%和28.03%(P<0.05);活性有机碳(LOC)分别显著提高19.20%、 44.02%和23.50%(P<0.05);碳库管理指数(CMI)分别显著提高20.94%、 46.86%和50.21%(P<0.05)。春玉米产量分别与LOC和CMI显著相关(P<0.05),而与TOC则无显著相关性。研究表明,LOC和CMI较TOC更能灵敏、 客观地反映渭北旱塬不同量秸秆覆盖还田对土壤碳库质量的影响,且秸秆覆盖量以9 000 kg/hm²为宜。

Effects of Different Rates of Straw Mulching and Returning to Field on Soil Labile Organic Carbon and Carbon Pool Management Index

A field experiment(2007-2010) was conducted at the Heyang Dryland Farming Experimental Station in Shaanxi Province of China to determine the effects of straw mulch rates on soil labile organic matter(LOC),carbon management index(CMI) and spring maize(Zea mays L.) yield.Maize straw at rates of 0(CK),4500(S1),9000(S2) and 13500 kg/hm2(S3) was placed on field plots.The results indicated that soil organic carbon(TOC) content of S1,S2 and S3 treatments increased by 5.08%,14.12% and 28.03%,respectively,compared with the CK at 0-20 cm soil layer;the LOC content increased by 19.20%,44.02% and 23.50%,respectively;the CMI increased by 20.94%,46.86% and 50.21%,respectively.Spring maize yield was found significantly(P<0.05) related to the LOC and CMI,while showed no significant correlations with the TOC.It was concluded that the LOC and CMI could reflect more rapidly and objectively the effects of different rates of straw mulch on soil carbon pool and maize yields more than TOC for the Weibei Dry Highland in China,besides,the treatment with 9000 kg/hm2 of straw mulch is preferable.