免耕对华北地区潮土碳库特征的影响

以实施7年的中国科学院禹城综合试验站冬小麦-夏玉米轮作免耕长期定位试验场为对象,系统研究免耕条件下土壤总碳(TC)、有机碳(SOC)、无机碳(SIC)的变化,为进一步评价免耕措施对华北地区潮土碳库的影响提供数据支持。研究设置免耕秸秆覆盖(NTRC)、免耕施用有机肥(NTRR)、常规耕作(CT)3种处理,分析表层(0-20cm)及深层(20-60cm)土壤TC、SOC及SIC的变化特征和影响因素。主要结果为:NTRC和NTRR能够增加0-20cm土层TC含量及储量,但降低20-60cm土层TC含量及储量,0-60cm总碳储量表现为NTRC>CT>NTRR;与CT相比,NTRC能够显著增加0-20cm而降低20-60cm土层SOC含量及储量,NTRR增加了0-5cm土层SOC含量及储量,在5-60cm则呈降低趋势,0-60cm土层SOC储量表现为CT>NTRC>NTRR;NTRC增加了0-60cm土层SIC储量,而NTRR则影响较小。TC与SOC呈显著正相关(P<0.05),而与SIC呈显著负相关(P<0.05),说明总碳的变化趋势与SOC一致,与SIC相反。

Effect of No-tillage on Fluvor-Aquic Soil Carbon Pool in North China

To further understand the effect of no-tillage(NT) on soil carbon pool in north China plain,the contents of soil total carbon,soil organic carbon and inorganic carbon under three different tillage systems for seven years at Yucheng Comprehensive Experimental Station,Chinese Academy of Sciences,which is a long-term no-tillage experimental site for the main crop rotation-winter wheat(Triticum aestivum L.) and summer maize(Zea mays L.),were investigated.No-tillage with residue cover(NTRC),no-tillage with residue removed and organic fertilization(NTRR) and conventional tillage(CT) treatments were set up.In addition,relationships among TC,SOC,SIC,pH,bulk density,MWD and GMD were analyzed.In comparision with CT treatment,total carbon stock increased in top soil(0-20 cm),but decreased in deep soil(20-60 cm) in both NTRC and NTRR treatments.The storage of TC in 0-60 cm soil depth was in order of NTRC(160.66 Mg/hm2) >CT(156.39 Mg/hm2) >NTRR(150.51 Mg/hm2).Total SOC content and stock were significantly increased in 0-20 cm soil layer,while those were decreased in 20-60 cm soil layer in NTRC treatment;SOC content and stock were increased in 0-5 cm,but decreased in 5-60 cm under NTRR;SOC stock in 0-60 cm soil layer under NT,NTRR,CT were 51.48,50.20,56.21 Mg/hm2,respectively.NTRC enhanced SIC accumulation for the whole profile(0-60 cm),while small changes were found in the storage of SIC under NTRR.Significant positive correlations(P<0.05) were observed between TC and SOC,while TC and SIC showed a significant negative correlation(P<0.05).