毛竹林地表稻草覆盖后翻耕对土壤有机碳的影响

Effects of straw mulching and scarification on soil labile organic carbon pool in a Phyllostachys edulis plantation

为了解毛竹林地表覆盖后翻耕对土壤总有机碳及土壤活性有机碳含量的影响,以浙江省台州市黄岩区山地毛竹林为研究对象,对连续覆盖2年翻耕,连续覆盖2年未翻耕和自然生长样地(对照)3种不同管理方式下地表覆盖的毛竹林0~50 cm土层土壤有机碳含量进行了比较。结果表明:覆盖2年未翻耕处理和覆盖2年翻耕处理0~50 cm各土层土壤总有机碳含量比对照样地分别增加了8.7%~43.8%和22.2%~90.8%;土壤轻组有机质含量较对照分别增加了13.2%~111.0%和36.7%~238.5%;覆盖2年翻耕处理和对照样地相比,0~50 cm各土层土壤易氧化碳含量分别增加了21.9%~97.5%,而覆盖2年未翻耕处理下的土壤易氧化碳含量0~20 cm土层较对照样地增加明显,20~50 cm土层则有减少的趋势;3种处理下的土壤水溶性有机碳含量,除10~20 cm土层差异性显著外,其余的土层变化都不明显;对照样地土壤水溶性有机碳占总有机碳的比率高于覆盖2年处理的毛竹林地,而易氧化碳占总有机碳的比率则表现为0~20 cm土层覆盖2年未翻耕>覆盖2年翻耕>对照样地,20~50 cm土层对照样地>覆盖2年翻耕>覆盖2年未翻耕;3种处理下土壤各活性有机碳与土壤总有机碳的相关性均达到极显著水平;3种处理方式下,土壤有机碳、水溶性有机碳、易氧化碳和轻组有机质与土壤养分(全氮、水解氮、有效磷、速效钾、交换性钙、交换性镁)的相关性均达到显著(P<0.05)或极显著(P<0.01)水平。

In order to understand the effects of tillage regimes after mulching with rice straws on soil total organic carbon （TOC） and labile organic carbon （LOC） contents in bamboo （Phyllostachys edulis） stands, we investigated the organic carbon contents in 0-50 cm soil layer of bamboo stands in Huangyan District of Taizhou, Zhejiang Province. The treatments were set as bamboo stands mulched continuously for two years with （MST） and without soil scarification （MWST）, and natural growth bamboo （CK）. The results showed that compared with the CK treatment, soil TOC and light fraction organic matter （LFOM） increased by 8.7%-43.8% and 22.2%-90.8%, 13.2%-111.0% and 36.7%-238.5%, when treated with MST and MWST respectively. The easilyoxidized carbon （EOC） content in the depth of 0-50 cm MST soils was enhanced by 21.9%-97.5% compared to CK condition, whereas the EOC content was enhanced obviously in the depth of 0-20 cm MWST soils, but decreased in the depth of 20-50 cm soils. In addition to the significant differences in 10-20 cm soil layer, the change of watersoluble organic carbon （WSOC） was not obvious in other soil layers under the three treatments. The ratio of soil WSOC to TOC in CK condition was higher than in the other two treatments. The ratio of EOC to TOC in depth of 0-20 cm soil layer displayed in order of MWST 〉 MST 〉 CK, and this ratio in the 20-50 cm soil layer decreased in the order of CK 〉 MST 〉 MWST. The correlation between each LOC and TOC reached a significant level （P〈0.01） under all treatments. Under the three treatments, soil TOC, WSOC, EOC, and LFOM exhibited significant （P〈0.05） or extremely significant （P〈0.01） correlations with soil nutrients （total nitrogen, hydrolyzable nitrogen, available phosphorus, available potassium, exchangeable calcium, exchangeable magnesium）.