高寒环境下耕地土壤质量变化及其驱动力分析——以西藏自治区拉萨市为例
文献类型：学位论文
| 作者 | 周忠浩 |
| 学位类别 | 博士 |
| 答辩日期 | 2009 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 多吉 ; 刘刚才 |
| 关键词 | 耕地 土壤酸化 土壤质量 驱动力 高寒环境 |
| 其他题名 | Dynamic Characteristics of Cultivated Soil quality and Its Driving Forces in High-frigid Environment—A case study in Lhasa,Tibet |
| 学位专业 | 自然地理学 |
| 中文摘要 | 青藏高原高寒区耕地是当地区域经济和社会生活的基本保障条件之一，其质量的好坏与变化直接影响到这一特殊区域的可持续发展。因此，高寒环境下耕地土壤质量的研究具有重要意义。 本研究选取拉萨市耕地土壤为研究对象，以土壤普查数据为基准，以野外调查、采样测试以及田间模拟试验为手段，分析拉萨市耕地土壤主要理化指标的变化及其驱动力。取得的主要结论如下： (1)自第二次土壤普查以来，拉萨市耕地土壤表层(0-20cm)砂化趋势明显；pH下降0.48个单位，土壤酸化趋势显现；土壤有机质、全氮磷钾保持稳定，速效氮和速效磷含量上升，速效钾含量显著下降。 (2)自第二次土壤普查以来，气温升高和降水增多等气候变化因素导致灌丛草原土(自然土壤)土壤pH和有机质含量有下降趋势。气候转暖使土壤有机质分解加速而导致有机质含量减少，但未达显著水平。耕地适量施肥能够补充土壤养分，降低酶活性，进而减弱气候变暖对土壤有机质的减少作用。在气候变化条件下，施肥较不施肥对土壤变化有更为明显的影响。 (3)拉萨市耕地土壤变化主要与长期施用氮磷肥或单施氮肥有关。氮肥施用提高的粮食产量增加土壤中钾的支出，导致土壤速效钾下降。铵态氮硝化及随后的NO3-淋溶导致土壤酸化。不同土壤类型反应差异明显：潮土抗酸化能力强，无论施肥与否，土壤pH值均保持稳定；而施用氮肥导致耕种灌丛草原土土壤pH值下降明显；这主要受土壤固有特性影响。 (4)耕地不同利用方式对于土壤发生层影响差异明显。种粮地B层土壤理化性质变化最大，主要由于深根根系积累有机质、淋溶作用造成速效氮增加所致。蔬菜地A层土壤理化性质变化最大，原因是蔬菜连茬种植和肥料投入高导致土壤酸化明显，速效养分积累明显；漫灌导致B层土壤氮磷积累。 (5)研究区施肥和灌溉目前虽然还没有造成地下水水质污染，但灌溉耕地氮肥使用量持续增加，而土壤保肥能力低，氮素易于淋失；加之当地地下水埋深浅，因此，地下水硝态氮污染潜在风险较高。 |
| 英文摘要 | High-frigid agriculture is located in Qinghai-Xizang plateau where it has ecological vulnerability and sensitivity of responses to global change. Environment-friendly agriculture is important to ensure economic growth and sustainable development. The research of Cultivated Soil quality is imperative to agricultural science for sustainable development in the high-frigid agricultural areas. The objective of this dissertation is to identify the dynamic characteristics of cultivated soil quality and its driving forces in high-frigid environment in the period from 1980s to 2007. By field investigation, pot-experiment and Lab analysis, the study was carried out in 2007-2008. The main conclusions were as the following: （1）Compared to the background value of soil quality based on the second soil survey of China(1980s), cultivated soil showed an coarsing tendency of soil particles with decreasing of silt and clay particles; and an acidification tendency with soil average pH value of the upper layer declines 0.48 units；there was no significant difference in overall average of organic matter(OM), total nitrogen(TN)，total phosphorus(TP)，total potassium(TK); available nitrogen (AN) and available phosphorus(AP) showed increasing tendencies; but available potassium (AK) showed an acidification tendency. （2）With annual temperatures and precipitation exhibit increasing tendency, the pH and OM content of Ustic Cambisols in grasslands were declining but were significant. Accelerated decompose of OM caused by climate warming up was useful to improve nutrient availability. （3）Application of chemical fertilizers and acid deposition could be the reasons causing the decrease of pH values in the soils. But it showed difference in evidence for different soil types. A significant increase of fertilizer input, particularly ammonium nitrogen fertilizer, most likely caused the severe acidification in Ustic Cambisols. Soil pH values in Och Aquic Cambisols showed slight decrease from 7.70 to 7.40. The difference of the soil intrinsical properties is the main internal factors causing the different changes of pH values in various types of soils. （4）The effects of different cultivated land use on soil genetic layers were different in evidence.In vegetable base, the change of soil quality obviously in A layer and slightly in B layer and C layer, because of heavy application of fertilizers with successive planting result in severe soil acidification but TN, TP, and TK content had not accumulated in A layer. At the same time, flood irrigation result in N- and P- accumulation occurred in B layer. But in grain crops field, the change of soil quality obviously in B layer and slightly in A layer and C layer, because of deep root fund OM and eluviations add available nitrogen in B layer.The difference in cultivation，fertilization，irrigation and drainage activities related to cultivated land use may affect the soil quality and soil genetic layers directly．（5）Nitrate pollution in shallow groundwater had not occurred in study area. Sandy loam has low nutrient-keeping capability in Lhasa. A great quantity of nutrient entered into environment, which might cause a potential risk of the shallow groundwater pollution, so it is urgently necessary to do further research on keeping nutrients balance between crop demands and fertilizer inputs. |
| 学科主题 | 土壤学 |
| 语种 | 中文 |
| 公开日期 | 2010-10-13 |
| 分类号 | S15;R65 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2142]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） |
| 推荐引用方式 GB/T 7714 | 周忠浩. 高寒环境下耕地土壤质量变化及其驱动力分析——以西藏自治区拉萨市为例[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2009. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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