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河西边缘绿洲荒漠沙地开垦后土壤性状演变及土壤碳积累研究
引用本文:苏永中,张珂,刘婷娜,范桂萍,王婷.河西边缘绿洲荒漠沙地开垦后土壤性状演变及土壤碳积累研究[J].中国农业科学,2017,50(9):1646-1654.
作者姓名:苏永中  张珂  刘婷娜  范桂萍  王婷
基金项目:国家自然科学基金(91425302,41401337)
摘    要:【目的】土壤养分变化及碳积累过程是评价绿洲农田生态系统结构、功能和生产力演化的重要指标。本研究的目的是通过了解西北干旱区自然荒漠开垦为灌溉农田后该指标的变化,揭示干旱区新垦农田土壤发育及演变规律,为新垦沙地持续利用提供指导。【方法】选择河西走廊中段临泽边缘绿洲0—46年开垦时间序列的沙地农田,取样分析0—60 cm土壤剖面的物理、化学性状变化及碳积累特征,通过比较2008年与2014年的耕层土壤(0—20 cm)测定结果,分析近几年土壤性状的变化。【结果】耕层土壤砂粒含量随开垦利用年限的增加而逐渐降低,但显著的变化发生在开垦16年后的农田,且最近10年土壤粒级组成变化不明显;在沙地开垦后的最初20年,耕层土壤有机碳(SOC)及全氮含量呈线性增加,20年后增加趋势减缓。开垦46年后,SOC、全氮、碱解氮、速效磷含量分别增加了9.0倍、6.3倍、6.3倍和13.5倍,耕层土壤无机碳(SIC)含量增加了77.1%;速效钾随开垦年限的增加呈先降低而后增加的趋势。20—40 cm和40—60 cm土层SOC及氮、磷、钾养分含量随开垦年限延长而逐渐增加,但变化幅度小于耕层土壤。2008—2014年的6年间,不同开垦年限的同一地块耕层土壤粒级组成未发生变化,但SOC及氮、磷、钾养分有明显的积累。沙地开垦46年后0—60 cm土层SOC、SIC和全碳的年平均固存量分别为0.75、0.79和1.47 kg·hm-2·a-1;SOC的积累主要发生在0—20 cm耕作层,而SIC的积累在40—60 cm土层。荒漠沙地转变为灌溉农田后有巨大的碳固存潜力;土壤黏粉粒增加对SOC及养分的积累和保持起重要作用。【结论】沙地开垦为灌溉农田后,随利用年限的增加,土壤肥力显著改善,但开垦46年后土壤肥力仍处于较低水平。对新垦沙地农田,要实现土地可持续利用和生产力持续提高,须采取提升土壤肥力水平的农田管理措施。

关 键 词:土壤性状变化  土壤碳积累  开垦时间序列  荒漠沙地  河西走廊绿洲
收稿时间:2016-07-21

Changes in Soil Properties and Accumulation of Soil Carbon After Cultivation of Desert Sandy Land in a Marginal Oasis in Hexi Corridor Region,Northwest China
SU YongZhong,ZHANG Ke,LIU TingNa,FAN GuiPing,WANG Ting.Changes in Soil Properties and Accumulation of Soil Carbon After Cultivation of Desert Sandy Land in a Marginal Oasis in Hexi Corridor Region,Northwest China[J].Scientia Agricultura Sinica,2017,50(9):1646-1654.
Authors:SU YongZhong  ZHANG Ke  LIU TingNa  FAN GuiPing  WANG Ting
Institution:Linze Inland River Basin Research Station, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences/Key Laboratory of Ecohydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou 730000
Abstract:【Objective】Changes in soil nutrients and process of soil carbon accumulation following the conversion of desert sandy land to irrigation cropland in arid region in northwest China is an important indicator for evaluating oasis ecosystem structure, function and productivity evolution. It is also one of the aspects for understanding soil development process and its evolution patterns on the newly cultivated farmlands in arid region.【Method】In this study, the temporal changes in soil physical and chemical properties in the 0-60 cm soil layers were determined in a 0-46 year cultivation sequence in the Linze marginal oasis. Soil properties in the plough layer (0-20cm) between 2008 and 2014 were compared to determine the changes of soil properties within the recent 6 years.【Result】The results indicated that sand content in the 0-20cm surface layer showed a consistent decreasing pattern with increasing duration of cultivation, but significant changes in particle size distribution only occurred in soils cultivated for more than 16 years. Within the recent 10 years, no significant changes in soil particle size distribution were detected. As cultivation time increased, soil organic carbon (SOC), total N and available N and P concentrations all increased. SOC and total N showed a rapid and linear increase in the initial 20 years after cultivation, and thereafter, had a slow increase. SOC, total N, and available N and P concentrations increased by 9.0 times, 6.3 times, 6.3 times and 13.5 times, respectively, after 46 years of continuous cropping. Soil inorganic carbon (SIC) increased by 77.1% after cultivation of 46 years. Available K concentration showed a decrease in the initial 20 years of cultivation, and subsequently, had a rapid increase. Also, SOC, N, P and K concentrations in the 20-40 cm and 40-60 cm soil layers gradually increased with increasing cultivation time, but the increase extent was far less than that of surface soil. During the 6 years period from 2008 to 2014, no significant changes in soil particle size distribution in the plough layer were found, however, SOC, N, P and K nutrients showed a distinct accumulation. After 46 years of continuous cropping, SOC, SIC and total C sequestration rate was 0.75, 0.79 and 1.47 kg·hm-2·a-1, respectively. SOC accumulation occurred mainly in the surface soil, SIC accumulation was found in the 40-60 cm soil layer. Conversion of sandy desert soils to irrigation croplands had a tremendous soil carbon sequestration potential. The increased silt and clay content play an important role in SOC and nutrients accumulation and retention.【Conclusion】After cultivation of native sandy lands and subsequently, continuous cropping improved significantly soil fertility. However, soil fertility was still in a low status after 46 years of cropping. Therefore, improved agricultural management is imperative to accelerate soil fertility improvement and maintain long-term productivity of the newly reclaimed sandy farmlands.
Keywords:changes in soil properties  soil carbon accumulation  cultivation sequence  desert sandy land  oasis in Hexi Corridor Region
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