【作者】 程登喜；

【导师】 张自和； 宋宝兴；

【作者基本信息】 兰州大学 ， 草业科学， 2007， 硕士

【摘要】 土地沙化，是指因人类不合理活动所导致的天然沙漠扩张和沙质土壤上植被及覆盖物被破坏，形成流沙及沙土裸露的过程。土地沙化是全球性的生态问题，是当今世界上最严重的环境问题之一，是严重影响人们生产生活的重大自然灾害。荒漠化问题已影响到全球100余个国家的36亿hm~2的土地，全世界陆地面积约1／3是干旱、半干旱荒漠地，而且每年以6万hm~2的速度在扩大。甘肃省沙漠化土地主要分布在河西走廊的腾格里、巴丹吉林和库姆塔格三大沙漠的前沿及其与绿洲的交接地带，风沙线东西长1600km，约66.7万hm~2的流动沙丘直接威胁着全省重要产粮基地的安全，土地沙化面积已经达到1203.5万hm~2，占全省国土总面积的28.3％，范围涉及8个市、州的24个县市区，不仅面积较大、分布集中，而且危害严重、扩展很快，使河西地区变成了全国四大沙尘暴策源地之一，直接危及全省大部分地区的生态安全。曾有“绿洲”美誉的民勤县有94％土地已经沙化。沙化土地面积的扩大，加剧了全省生态环境的恶化程度，严重制约着我省经济的可持续发展。2001年以来，温家宝总理就民勤的生态建设多次做出重要批示，要求全力以赴加快石羊河流域重点治理，决不能让民勤成为第二个罗布泊。尽管如此，荒漠化和土地沙化的总体形势仍然很严峻，主要表现在：①我国荒漠化、沙化土地面积基数大，防治任务十分艰巨。②导致荒漠化形成的诱因还没有消除，荒漠化地区经济社会发展缓慢与该地区群众对经济利益和物质文化需求快速增长之间的矛盾依然尖锐。根据对沙化地的研究和实践现状的认识，作者认为高分子吸水材料的科学应用，是解决沙化地增产问题的一个发展方向。由此提出本文研究工作的思路——围绕高分子吸水材料的科学应用展开本项研究工作：首先在查阅资料和现场调查的基础上，详细研究了沙化地和高分子吸水材料的特殊性；并在使用高分子吸水材料的条件下，研究水分和养分在沙化地土壤中传输的科学规律；以西北沙化区具有典型代表意义的农作物——马铃薯作为主要对象，检验本项研究工作的思路和技术方案的正确性和有效性。在整个研究工作中，既充分关注科学性，又充分关注实用性和可操作性。本项研究采用现有资料的查阅与实际试验相结合、室内模拟实验与田间试验相结合的技术路线，进行了下述主要方面的研究：(1)通过沙层条件下线性高分子吸水材料不同处理的试验，研究提高沙层的含水量、速效氮含量与马铃薯根系在沙层中的真实分布情况。(2)根据沙化地的特殊性，对试验地的基础养分状况和不同种植年限的沙地条件进行测定，对马铃薯播种后的生长过程进行分析，并对马铃薯的产量进行测定与分析，得出马铃薯在沙化地的较好种植模式，以指导农民进行农业生产。(3)通过以上试验，在受到约束的条件下，使水分和速效氮的下渗量明显减小，较大幅度地提高沙层的含水量和速效氮含量，为降低化肥使用量，提供可参考性的依据，并找到一条用高分子吸水材料改造、治理沙化地的途径。根据文献资料和现有的实际应用情况，试验选用由西北工业大学研制的线性分子结构的丙烯酸钾-丙烯酰胺聚合物，作为目前高分子吸水材料的代表样品来进行研究。本研究取得的主要成果：1．经过模拟试验，发现高分子吸水材料的吸水特性和对吸附、保持土壤水分的特性是有区别的，以前仅以吸附去离子水量，作为衡量吸水材料应用效果的方法，不能反映吸水材料在土壤溶液环境下的实际作用规律。2．提出的定位定量施用高分子吸水材料的方法，改变了水分和养分在沙层中的扩散分布，在作物主要根系分布的沙层中，实现了水分和主要养分的同步富集，实验地沙层速效氮的含量比对照增加了87.3％，水分含量也比对照明显增加。结果表明，用高分子水溶胶定位定量施用来改良沙化地，是一种具有研发潜力和推广价值的方法。3．经过测定发现，马铃薯的根系发育深度在0～20cm之间，此深度范围的鲜根重量占到鲜根总量的86.4％。其中以5～15cm深度范围的根系密度最大，占到鲜根总量的56.9％。4．高分子吸水材料的应用，使作物根系周围富集了较多的水分和养分，促进了作物根系的发育，使马铃薯的根鲜重和根干重分别多出了74.87％和69.35％。5．发现影响高分子吸水材料提高沙层含水量的主要因素有，高分子聚合物的分子结构、沙层中的含泥量、施用方法、施用位置及用量。6．常规条件下的沙化地，影响作物产量的因素主要是种植年限，即因灌溉黄河水所增加的沙层中的含泥量。在沙层含泥量低、水分和速效氮吸附能力差的沙化地中，经过聚合物的处理，改善了沙化地所种植作物的养分供给，马铃薯总产量超过了种植条件相对较好的沙壤土质地块。更多还原

【Abstract】 Desertification is defined as a result that natural desert expansion and vegetation cover is destroyed in sandy soil and the exposed sand and quicksand are formated by unreasonable human activities.Desertification is a global ecological problems,the one of the world’s most serious environmental problem and natural disasters which people’s production and livelihood of major are affected seriously. The problem of desertification has affected 3.6 billion hm~2 of land in more than 100 countries., the world land area of about 1/3 is arid, semi-arid desert, but Desertification is enlarging at the rate of expansion every year 60,000 hm~2.Gansu Province desertified land are distributed mainly in the forefront and the transition zone of oasis which located in Tengger, Badain Jaran and Kumutage desert,landline is 1,600 km from east to west at length and about 667,000 ha of mobile dunes are directly threatened the province’s major grain-producing base security. Desertified land area has reached 12.035 million ha,which accounting for the province’s total land area of 28.3% and covering the 24 counties in eight cities,it is not only larger and centralized in distribution, but also a serious threat and expand quickly,which it result in Hexi area where became one of the four major source of dust storms, the province most directly threaten the ecological safety. There has been the "Oasis" Minqin County’s reputation as a 94 percent land has been desertified. The expansion of desertified land area, the province’s ecological environment exacerbated the extent of the deterioration, seriously restricting the sustainable economic development of our province. Since 2001, Premier Wen Jiabao on the ecological construction Minqin made important instructions on many occasions, go all out to speed up the Shiyang River Basin requirements focus governance, must not be allowed to become the second Minqin Lop Nor.Nevertheless, desertification and sandyland of the overall situation remains grim.It shows mainly as follows: First, the area of China desertification and sandy land base is large and the task is very arduous.Second, incentives lead to the formation of desertification has not been eliminated,the contradiction between slow economic and social development in the region and rapid growth of the masses of material and cultural demand for the people dewlling the region is still sharp.According to research of the deserts and understanding of the practice status, the authors believe that superabsorbent polymer materials science applications is a development direction to solve increasing production of desertification. This raised the idea of this research - it start the research around polymeric absorbent material on the scientific application: First, the special nature of polymeric and absorbent materials have been studied in detail by data access and on-site investigation; scientific laws of transmission of moisture and nutrients have been studied under the conditions of the use of absorbent material in the polymer; with a typical representative of potato crops as a main target in Northwest sandy areas, legitimacy and effectivity of the ideas and the technical program have been tested. Throughout the study, both full attention scientific, and full attention practical, and serviceable have been considered.The study used routes of technology which combined the existing data access with the actual test, which combined indoor simulated experiments with field test, the following main areas of research were carried out:First,it may raise sand layer on the water content, available nitrogen content and the real distribution of potato root in the sand layer under the conditions of the use of polymeric absorbent material with different tests.Second,we would test nutrient status and conditions of sand different planting years in the field,analyze the growth process of potatoes after sowing and the production of potatoes,and the conclusion that the better cropping patterns can adjust to potatoes can be arrived at ,which guide farmers to undertake agricultural production.The last, Through these experiments, in the constrained conditions, the water and the infiltration of available N significantly were reduced, sand layers and the available nitrogen content of moisture were enhanced greatly,it provide referenc to reduce the use of chemical fertilizers, and find a way to control desertification to use polymeric absorbent material transformation.According to written information and the practical application, as the current high representatives of superabsorbent material samples-- the potassium acrylate -acrylamide polymer were chose ,which were made by the Northwestern Industry University.The major achievements of this study has made:1. After simulation test and found that the absorbent polymer absorbent material properties and adsorption, and maintain the characteristics of soil moisture is differentiated,Previously only adsorption deionized water absorbent materials as a measure of effectiveness of the method, does not reflect the absorbent material in the soil solution in the actual effects of environment laws.2. The application of quantitative positioning superabsorbent polymer materials, changes the moisture and nutrients in the sediment layer diffusion distribution, mainly root crops in the distribution of sand layers, and achieving the water and the main nutrient enrichment synchronization, experimental and sand layers available N content than the control increased by 87.3 %. Results showed that using polymer hydrosol positioning quantitative application to upgrade deserts, is a kind of research and development potential and to promote value method.3. The result indrcated that the depth of Potato root development is 0 to 20 cm .between the depth that the fresh root weight account for the total 86.4%. thereinto 5～15 cm depth ,the root system is the greatest density, account for the total of fresh root 56.9%.4. Polymeric absorbent material around the root crops enriched with more moisture and nutrients, and promote the development of root crops, potatoes fresh weight of the root and root dry weight were more of 74.87% and 69.35%.5. Found that the impact of superabsorbent polymer materials raising sand layer moisture has a major factor, the molecular structure of polymers, mud contend in sand layer, application method, location and amount of application.6. Desertification under conventional conditions, factors affecting crop yield is the main planting period, that is due to the increase in irrigation water of the Yellow River mud containing in sediment layer . In the sand layer with a low volume of mud, water and available nitrogen adsorption capacity is poor in this desertification, by the polymer processing, improved crops plants the nutrient supply in the desertification .the total output of potato more than cultivation conditions relatively good sandy loam texture block.更多还原