【摘要】：選取亞熱帶四種典型母質(花崗巖風化物、第四紀紅色粘土、板頁巖風化物、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比,通過室內模擬培養(yǎng)試驗研究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化的特征與差異。結果表明:在180 d的培養(yǎng)期內,所選4種稻田土壤中外源輸入秸稈的累積礦化率(18%—21%)均顯著低于對應的旱作土壤(21%—28%),外源秸稈的輸入對土壤原有有機碳礦化的激發(fā)效應也是以稻田土壤(5%—30%)明顯低于對應的旱作土壤(17%—65%)。外源秸稈在土壤中的分解產(chǎn)物主要向顆粒有機碳(POC)和鐵鋁結合態(tài)有機碳(Fe/Al-OC)分配,分配比例分別為9%—21%和12%—24%,其次為腐殖質碳(HMC)(11%—15%),而向微生物生物量碳(MBC)和溶解性有機碳(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應的旱作土壤之間并無顯著差異。本研究結果說明,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)性團聚體的物理保護、與氧化鐵鋁的化學鍵合以及向有機碳穩(wěn)定組分的分配作用較強有關,從而貢獻于稻田土壤較高的有機碳積累。
[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】： 中國科學院亞熱帶農(nóng)業(yè)生態(tài)研究所亞熱帶農(nóng)業(yè)生態(tài)過程重點實驗室;中國科學院大學;
【基金】：國家自然科學基金項目(41371252,41430860,41671242) 國家重點研發(fā)計劃項目(2016YFD0300902)
【分類號】：S141;S153

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