秸秆还田模式对土壤有机碳及腐植酸含量的影响

通过9年水稻-小麦轮作田间定位试验,探讨南方稻麦两熟制农田秸秆还田模式对土壤有机碳(SOC)和腐植酸(HE)的影响。试验设置仅麦秆稻季还田(W)、仅稻秆麦季还田(R)、秸秆稻麦季均还田(RW)和秸秆均不还田(CK)共4个处理。结果表明,秸秆还田显著(P0.05)提高了0~10 cm土层SOC,对土壤总氮(TN)无明显影响;不同秸秆还田模式处理下,0~10 cm土层SOC及TN大小为WRWRCK;10~20 cm SOC及TN大小均为WCKRWR,但各处理之间的差异均不显著。秸秆还田处理中,0~10 cm土层土壤HE、富里酸(FA)和胡敏酸(HA)均低于CK,而在10~20 cm土层则高于CK。不同秸秆还田方式间,0~10 cm土层的HE、FA和HA以W处理为最高,其土壤腐殖化程度最大;而10~20 cm土层则以RW处理为最高,W处理的土壤腐殖化程度最小。相比其他秸秆还田模式,麦秸稻季还田能更好地提高土壤表层有机碳含量和腐殖质品质。

Effects of returning patterns of straw to field on soil organic carbon and soil humus composition in rice-wheat double cropping systems

A 9-years field experiment was conducted in Suzhou, Jiangsu Province of China, to study the effects of returning patterns of straw to field on soil organic carbon(SOC) and humus composition in the Taihu Lake Region, a typical rice-wheat rotation region. Four returning patterns were operated, i.e., only wheat straw returning to field(W), only rice straw returning to field(R), both rice and wheat straw returning to field(RW) and no straw returning to field(CK). Soil samples from 0~10 cm and 10~20 cm soil layers were collected to analyze contents of SOC, total nitrogen(TN), humus acid(HE), fulvic acid(FA) and humilic acid(HA). The results indicated that returning straw could significantly(P<0.05) increase SOC contents in 0~10 cm soil layer, compared with that of CK, while no significant effects were found on TN contents. The contents of SOC and TN at 0~10 cm and 10~20 cm soil layers showed the orders of W > RW > R > CK and W > CK > RW > R, respectively. However, no significant differences of SOC and TN contents were found between the three straw returning patterns at the two soil layers. Compared with CK, HE, FA and HA were lower at 0~10 cm soil layer of straw returning treatments; whereas they were higher than that in CK at 10~20 cm soil layer. The contents of HE, FA and HA were the highest in soils from W treatment, while those were highest in soils from RW treatment. The PQ value(HA/HE) in W treatment was the highest at 0~10 cm soil layer, while the lowest at 10~20 cm soil layer. The results from this study showed that only wheat straw returning to field was the best pattern to improve SOC content and the soil humus quality at 0~10 cm soil layer, compared with other straw returning patterns.