【摘要】：選取亞熱帶四種典型母質(zhì)(花崗巖風(fēng)化物、第四紀(jì)紅色粘土、板頁(yè)巖風(fēng)化物、近代河流沉積物)發(fā)育的稻田土壤,以毗鄰的旱作土壤為對(duì)比,通過(guò)室內(nèi)模擬培養(yǎng)試驗(yàn)研究45%田間持水量(WHC)條件下稻田和旱作土壤中外源輸入秸稈礦化和轉(zhuǎn)化的特征與差異。結(jié)果表明:在180 d的培養(yǎng)期內(nèi),所選4種稻田土壤中外源輸入秸稈的累積礦化率(18%—21%)均顯著低于對(duì)應(yīng)的旱作土壤(21%—28%),外源秸稈的輸入對(duì)土壤原有有機(jī)碳礦化的激發(fā)效應(yīng)也是以稻田土壤(5%—30%)明顯低于對(duì)應(yīng)的旱作土壤(17%—65%)。外源秸稈在土壤中的分解產(chǎn)物主要向顆粒有機(jī)碳(POC)和鐵鋁結(jié)合態(tài)有機(jī)碳(Fe/Al-OC)分配,分配比例分別為9%—21%和12%—24%,其次為腐殖質(zhì)碳(HMC)(11%—15%),而向微生物生物量碳(MBC)和溶解性有機(jī)碳(DOC)分配的比例極小,分別僅為2%—7%和0.1%-0.7%。與旱作土壤相比,稻田土壤中外源秸稈的分解產(chǎn)物向POC、Fe/Al-OC和MBC分配的比例較高,分別為15%—21%、17%—24%和6%—7%,而旱作土壤為9%—17%、13%—18%和2%—4%。此外,外源秸稈分解產(chǎn)物向2000—250μm水穩(wěn)性粗團(tuán)聚體分配的比例也以稻田土壤(10%—13%)高于旱作土壤(6%—7%),其它粒徑中稻田與對(duì)應(yīng)的旱作土壤之間并無(wú)顯著差異。本研究結(jié)果說(shuō)明,稻田土壤中外源輸入秸稈的礦化率低于旱作土壤的現(xiàn)象在不同母質(zhì)類型的土壤中可能普遍存在,這可能與稻田土壤中外源秸稈分解產(chǎn)物受水穩(wěn)性團(tuán)聚體的物理保護(hù)、與氧化鐵鋁的化學(xué)鍵合以及向有機(jī)碳穩(wěn)定組分的分配作用較強(qiáng)有關(guān),從而貢獻(xiàn)于稻田土壤較高的有機(jī)碳積累。
[Abstract]:Four typical parent materials (granite weathering, Quaternary red clay, plate shale weathering, modern river sediment) developed in the subtropics were selected and compared with adjacent dryland soils. The characteristics and differences of exogenous straw mineralization and transformation in paddy field and dryland soil under the condition of 45% field water holding capacity (WHC) were studied by simulated cultivation in laboratory. The results showed that the cumulative mineralization rate (18-21%) of exogenous straw in the selected four paddy soils was significantly lower than that in the corresponding dryland soil (21-28%) during the 180 d culture period. The stimulation effect of exogenous straw on the mineralization of soil organic carbon was also significantly lower in paddy soil (5- 30%) than in the corresponding dryland soil (17-65%). The decomposition products of exogenous straw in soil were mainly distributed to particulate organic carbon (POC) and iron-aluminum bound organic carbon (Fe/Al-OC), with the distribution ratios of 9- 21% and 12-24%, respectively. The next was humus carbon (HMC) (11-15%), but the proportion to microbial biomass carbon (MBC) and dissolved organic carbon (DOC) was very small, which was only 2 -7% and 0.1% -0.7%, respectively. Compared with dry soil, the ratio of decomposition products of exogenous straw to POC,Fe/Al-OC and MBC in paddy soil was 15-21%, 17-24% and 6-7%, respectively, while that in dryland soil was 9-17%. 13-18% and 2-4%. In addition, the proportion of decomposition products of exogenous straw to water-stable coarse aggregates of 2000-250 渭 m was also higher in paddy soil (10- 13%) than in dryland soil (6- 7%). There was no significant difference between the paddy field and the corresponding dry soil in other particle sizes. The results show that the mineralization rate of exogenous straw in paddy soil is lower than that in dry soil, which may be widespread in different parent material types of soil. This may be related to the physical protection of exogenous straw decomposition products from water-stable aggregates in paddy soils, the chemical bonding of iron and aluminum oxide and the distribution of organic carbon stable components. Thus contribute to the higher accumulation of organic carbon in paddy soil.
【作者單位】： 中國(guó)科學(xué)院亞熱帶農(nóng)業(yè)生態(tài)研究所亞熱帶農(nóng)業(yè)生態(tài)過(guò)程重點(diǎn)實(shí)驗(yàn)室;中國(guó)科學(xué)院大學(xué);
【基金】：國(guó)家自然科學(xué)基金項(xiàng)目(41371252,41430860,41671242) 國(guó)家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2016YFD0300902)
【分類號(hào)】：S141;S153

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