【摘要】：【目的】土壤養(yǎng)分變化及碳積累過程是評價綠洲農(nóng)田生態(tài)系統(tǒng)結構、功能和生產(chǎn)力演化的重要指標。本研究的目的是通過了解西北干旱區(qū)自然荒漠開墾為灌溉農(nóng)田后該指標的變化,揭示干旱區(qū)新墾農(nóng)田土壤發(fā)育及演變規(guī)律,為新墾沙地持續(xù)利用提供指導。【方法】選擇河西走廊中段臨澤邊緣綠洲0—46年開墾時間序列的沙地農(nóng)田,取樣分析0—60 cm土壤剖面的物理、化學性狀變化及碳積累特征,通過比較2008年與2014年的耕層土壤(0—20 cm)測定結果,分析近幾年土壤性狀的變化。【結果】耕層土壤砂粒含量隨開墾利用年限的增加而逐漸降低,但顯著的變化發(fā)生在開墾16年后的農(nóng)田,且最近10年土壤粒級組成變化不明顯;在沙地開墾后的最初20年,耕層土壤有機碳(SOC)及全氮含量呈線性增加,20年后增加趨勢減緩。開墾46年后,SOC、全氮、堿解氮、速效磷含量分別增加了9.0倍、6.3倍、6.3倍和13.5倍,耕層土壤無機碳(SIC)含量增加了77.1%;速效鉀隨開墾年限的增加呈先降低而后增加的趨勢。20—40 cm和40—60 cm土層SOC及氮、磷、鉀養(yǎng)分含量隨開墾年限延長而逐漸增加,但變化幅度小于耕層土壤。2008—2014年的6年間,不同開墾年限的同一地塊耕層土壤粒級組成未發(fā)生變化,但SOC及氮、磷、鉀養(yǎng)分有明顯的積累。沙地開墾46年后0—60 cm土層SOC、SIC和全碳的年平均固存量分別為0.75、0.79和1.47 kg·hm-2·a-1;SOC的積累主要發(fā)生在0—20 cm耕作層,而SIC的積累在40—60 cm土層。荒漠沙地轉(zhuǎn)變?yōu)楣喔绒r(nóng)田后有巨大的碳固存潛力;土壤黏粉粒增加對SOC及養(yǎng)分的積累和保持起重要作用�！窘Y論】沙地開墾為灌溉農(nóng)田后,隨利用年限的增加,土壤肥力顯著改善,但開墾46年后土壤肥力仍處于較低水平。對新墾沙地農(nóng)田,要實現(xiàn)土地可持續(xù)利用和生產(chǎn)力持續(xù)提高,須采取提升土壤肥力水平的農(nóng)田管理措施。
[Abstract]:[objective] the change of soil nutrient and the process of carbon accumulation are important indexes for evaluating the structure, function and productivity evolution of oasis farmland ecosystem. The purpose of this study is to reveal the development and evolution of newly reclaimed farmland in arid areas by understanding the changes of this index after the reclamation of natural deserts into irrigated farmland in the arid areas of northwest China. [methods] the cultivated land of Linze marginal oasis in the middle part of Hexi Corridor was selected and the change of physical and chemical properties and the characteristics of carbon accumulation in 0 ~ 60 cm soil profile were analyzed by sampling and analyzing the time series of reclamation time series in the middle part of Hexi Corridor. The changes of soil properties in recent years were analyzed by comparing the results of soil cultivation in 2008 and 2014 (0? 20 cm). [results] the content of sand grains decreased gradually with the increase of reclamation and utilization years. However, the significant change occurred in the farmland after 16 years of reclamation, and the change of soil particle size composition was not obvious in the last 10 years. In the first 20 years after land reclamation, the organic carbon (SOC) and total nitrogen (TN) content in cultivated soil increased linearly, but the increasing trend slowed down after 20 years. After 46 years of reclamation, the contents of total nitrogen, alkali-hydrolyzed nitrogen and available phosphorus of SOC, increased by 9.0 times, 6.3 times and 13.5 times, respectively, and the (SIC) content of inorganic carbon in cultivated soil increased by 77.1%. The available potassium decreased at first and then increased with the increase of reclamation time. The contents of SOC, nitrogen, phosphorus and potassium in 20 ~ 40 cm and 40 ~ 60 cm soil layers gradually increased with the increase of reclamation time. In the six years from 2008 to 2014, there was no change in the grain size composition of the same soil in the same plot with different reclamation years, but SOC and nitrogen, phosphorus and potassium nutrients had obvious accumulation. The average annual sequestration of SOC,SIC and total carbon in 0 / 60 cm soil layer was 0.75, 0.79 and 1.47 kg 路hm-2 路a-1 respectively after 46 years of reclamation. The accumulation of SOC mainly occurred in 0-20 cm tillage layer, while the accumulation of SIC in 40-60 cm soil layer. There is great carbon sequestration potential after the desert sandy land is transformed into irrigated farmland. [conclusion] the increase of soil clay grain plays an important role in the accumulation and maintenance of SOC and nutrients in sandy land. [conclusion] after reclamation into irrigated farmland, the soil fertility improved significantly with the increase of utilization years, but the soil fertility was still at a relatively low level after 46 years of reclamation. In order to realize the sustainable use of land and the continuous improvement of productivity, farmland management measures should be taken to improve the level of soil fertility in newly cultivated sandy land.
【作者單位】： 中國科學院西北生態(tài)環(huán)境資源研究院臨澤內(nèi)陸河流域研究站/中國科學院內(nèi)陸河流域生態(tài)水文重點實驗室;
【基金】：國家自然科學基金(91425302,41401337)
【分類號】：S151.9
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本文編號：2467909