东北黑土区旱田改种稻田后土壤有机碳（氮）的变化特征

发布时间：2018-03-07 14:23

  本文选题：黑土　切入点：旱田改种稻田　出处：《沈阳农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：黑土是我国东北地区重要的土壤资源,近年来,该区域由旱田改种稻田的面积逐年增加。旱田改种稻田后土壤环境发生明显的变化,在短期淹水(年约4～5个月)环境条件下土壤碳(氮)的演变规律如何?目前尚不清楚。土壤有机碳(氮)作为衡量土壤肥力的重要指标,科学地评价黑土区旱田改种稻田后土壤有机碳(氮)的变化特征,对于东北黑土的合理利用和培肥具有重要意义。本文以东北典型黑土区旱田土壤(种植大豆年限大于60年)和改种不同年限的稻田土壤(3、5、10、17、20和25年,旱田改种稻田前种植历史基本相同,均为大豆)为研究对象,利用稳定性同位素技术、物理和化学分组技术等,研究了东北黑土区旱田开垦种稻后土壤有机碳(氮)、颗粒有机碳(氮)和键合有机碳的动态变化特征,有机碳(氮)及颗粒有机碳(氮)的稳定性,分析了旱田改种稻田后土壤有机碳(氮)变化的影响因素,探讨了旱田改种稻田后土壤有机碳(氮)的演变规律。主要研究结果如下:(1)东北黑土区旱田改种稻田25 a间,土壤有机碳、全氮含量及其0-60 cm 土层密度的变化趋势均表现为:在改种的3 a间迅速下降,在3～25 a间随改种年限延长呈逐渐增加的趋势,在改种5～25 a间0-60 cm 土层有机碳、全氮密度分别增幅9.87%～21.48%和10.2%～19.3%,土壤有机碳和全氮的变化密切相关(P0.01)。土壤δ13C值和δ15N值均呈逐年下降趋势,在5～25 a间二者数值均低于旱田土壤;相同年限土壤的δ13C值和δ15N值均随着土层加深而增大。(2)东北黑土区旱田改种稻田25 a间,土壤颗粒有机碳(氮)的分配比例为4.96%～12.73%(4.03%～13.07%),与旱田土壤(0a)相比,其提高幅度为6.8%～106.4%(0.7%～224.0%)。各年限0-40 cm 土层稻田土壤颗粒有机物中的δ13C值和δ15N均高于旱田土壤,相同年限的δ13C值均随土层加深而升高,而δ15N值则均随土层加深而降低。(3)东北黑土区旱田改种稻田25 a间,土壤键合有机碳的分配比例为41.06%～66.48%,均低于相同土层旱田土壤,在改种3～25 a间呈逐年降低趋势,且均随土层加深而增加;0-60 cm 土壤Fe(Al)-SOC的分配比率与其键合有机碳的变化相同,20-60 cm土壤Ca-SOC的分配比率则呈逐年增加趋势,但各年限土壤Fe(Al)-SOC明显高于Ca-SOC,Fe(Al)-SOC为土壤键合有机碳的主体。(4)东北黑土区旱田改种稻田25 a间,土壤pH、CEC及交换性Ca2+、不同形态氧化铁铝均随改种年限的延长而变化,但变化规律不相一致。通过相关分析和多元线性逐步回归分析发现,土壤阳离交换量(CEC)及交换性钙和络合态氧化铁(铝)是影响旱田改种稻田土壤有机碳及颗粒有机碳、键合有机碳变化的重要因素;土壤CEC及交换性Ca2+对土壤有机碳的变化起正作用,而络合氧化铁铝则起负作用。综上,东北黑土区旱田改种稻田25 a间,改种年限大于5 a后稻田土壤有机碳(氮)、颗粒有机碳(氮)逐年增加,化学键合有机碳则逐年下降,稻田土壤具有明显的固碳(氮)能力,有机碳(氮)在20-60 cm 土层易于累积且相对稳定;在0-20 cm 土层,易变化的颗粒有机碳相对累积,其分解性相对较为活跃。因此,旱田改种稻田年限小于5 a,应注重有机碳(氮)的补充,改种年限大于5 a,则应注重土壤有机碳(氮)的稳定性,以维持和提高旱田改种稻田后土壤有机碳(氮)水平及其稳定性。
[Abstract]:Black soil is an important soil resource in Northeast China in recent years, the area of upland rice by planting area increased year by year. Upland paddy field replant soil environment after obvious changes in short-term flooding (about 4~5 months) under the condition of soil carbon (nitrogen) how evolution law is not clear? Soil organic carbon (nitrogen) as an important indicator of soil fertility, the scientific evaluation of black soil area of upland rice after replant soil organic carbon (nitrogen) change characteristic, has important significance for rational utilization of black soil in Northeast China and fertilization. The typical upland black soil region of Northeast China (soybean planting age greater than 60 years) and from different years of paddy soil (3,5,10,17,20 and 25 years ago, upland paddy plant planting history is basically the same, are soybean) as the research object, the use of stable isotope techniques, physical and chemical technology research group. Upland rice cultivation in black soil region of Northeast China soil organic carbon (nitrogen), particulate organic carbon (nitrogen) and the key dynamic characteristics of combined organic carbon, organic carbon (nitrogen) and particulate organic carbon (nitrogen) stability analysis of upland rice after replant soil organic carbon (nitrogen) change of influencing factors. The paddy upland replant soil organic carbon (nitrogen) evolution. The main results are as follows: (1) to 25 upland black soil region of northeast paddy a, soil organic carbon, total nitrogen content and its change trend of 0-60 cm soil layer density are as follows: the rapid decline in the 3 to a, 3~25 in a with the plant life extension is gradually increasing, in the 5~25 a 0-60 cm to soil organic carbon, total nitrogen density were increased by 9.87% ~ 21.48% and 10.2% ~ 19.3%, the change of soil organic carbon and total nitrogen are closely related (P0.01). Soil 13C values and 15N values declined year by year, The value of 5~25 a between the two were lower than upland soil; the same soil Delta 13C values and 15N values increased with soil depth. (2) to 25 upland black soil region of northeast paddy field a, soil particulate organic carbon (nitrogen) proportion is 4.96% ~ 12.73% (4.03% ~ 13.07%), and upland soil (0A) compared to the increased from 6.8% to 106.4% (0.7% ~ 224%). The length of delta 13C 0-40 cm soil layer of paddy soil particulate organic matter in the value of 15N was higher than that of upland soils and delta, Delta 13C values were the same period with the soil depth increased, while the 15N values were decreased with soil further reduced. (3) to 25 upland black soil region of northeast paddy field a, the distribution proportion of soil organic carbon bond is 41.06% ~ 66.48%, were lower than the same soil in upland soils, to 3~25 A is decreasing year by year, and were increased with soil depth; 0-60 cm soil Fe (Al) distribution ratio with -SOC The change of organic carbon bond is the same as that of 20-60 cm soil Ca-SOC distribution ratio increased year by year, but the soil Fe (Al) -SOC was significantly higher than that of Ca-SOC, Fe (Al) -SOC as the main soil organic carbon bond. (4) to 25 upland black soil region of northeast paddy soil pH, a. CEC and exchangeable Ca2+, different forms of iron oxide aluminum was increased with the age to change, but the change is not consistent. Through correlation analysis and multivariate linear regression analysis showed that, soil cation exchange capacity (CEC) and exchangeable calcium and iron complexed (aluminum) is the effect of upland paddy soil organic carbon plant and particulate organic carbon, an important factor in bonding changes in organic carbon; soil CEC and exchangeable Ca2+ on changes of soil organic carbon is positive, and the complexation of Fe and Al oxides exerted negative effect. As a result, upland paddy field in the 25 A to the black soil region of Northeast China, to life is more than 5 A in paddy field Soil organic carbon (nitrogen), particulate organic carbon (nitrogen) increased year by year, chemical bonding of organic carbon in paddy soil decreased year by year, with significant carbon (nitrogen), organic carbon (nitrogen) is accumulated and relatively stable in the 20-60 cm soil layer; in 0-20 cm soil layer, easy to change particle organic carbon the relative cumulative, the decomposition of relatively active. Therefore, upland paddy replant years of less than 5 A, should pay attention to organic carbon (nitrogen) added to age greater than 5 A, should pay attention to soil organic carbon (nitrogen) stability, to maintain and enhance the upland rice after replant soil organic carbon (nitrogen) and its level stability.

【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S153.6
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本文编号：1579660