恩施州耕地土壤酸化现状及石灰等土壤调理剂降酸效果初探

发布时间：2019-06-24 21:40

【摘要】：自上世纪80年代至今,我国农田耕地土壤90%都呈现出了不同程度的酸化现象。25年来中国几乎所有土壤类型的pH值下降了0.13~0.80个单位,平均下降了0.5个单位,酸化现象十分普遍。湖北省恩施州地处武陵山区腹地,受环境、气候等自然因素和作物种植、施肥习惯等多种人为因素影响,耕地土壤酸化日益加重。因土壤酸化诱发的农产品产量和品质下降的问题也逐渐显现和扩展,成为恩施州农业生产稳步发展的新隐患。为了对恩施州及类似地区耕地土壤酸化问题进行较全面的了解,并为制定土壤酸化控制及治理对策提供依据,本研究以全国第二次土壤普查(1980—1983年)和耕地质量评价(2010—2013年)期间采集的大量土壤样品为基础,对恩施州耕地土壤pH值变化进行分析,明析恩施州土壤酸化现状及特征,采用培养试验和盆栽试验相结合的方法,探讨不同调理剂对于酸性土壤降酸效果及作物生长的影响,并通过田间试验进一步验证施用石灰效果和明确石灰适宜用量。主要研究结果如下:1、近30年来,恩施州土壤呈酸化趋势,土壤pH空间分布呈现东高西低格局。不同区域、不同耕地利用类型土壤pH值均发生不同程度的下降。第二次土壤普查期间,耕地土壤pH平均为6.5,经过30年耕地土壤pH降低至5.6,整体下降了0.90个单位,旱地土壤酸化程度大于水田。2、恩施州耕地土壤pH下降较快的因素是人为因素的强烈影响。主要是:肥料结构及配比的改变(化肥投入氮磷钾比例严重失调,有机肥用量急速下滑)、高产作物收获带走大量盐基养分(习惯施肥又未能使其得到有效的补充)、长期停施石灰(导致土壤酸性无法中和)等人为因素。3、不同类型的调理剂对酸性土壤的降酸效果不尽相同。通过一年试验的研究,其中以生石灰效果最好,到培养第90 d,相比于对照处理提高了0.66个pH单位,土壤交换性铝含量减少了2.01 cmol/kg。秸秆处理尽管没有有效降低土壤酸度但仍可明显促进作物生长,因此也可用作酸性土壤的改良物质,在实际生产中应因地制宜应用各种调节物质来促进作物生长。4、评价碱性物料改良酸性土壤的适宜评价指标是潜在酸(土壤交换性酸总量、土壤交换性H+和土壤交换性铝)。随着培养时间的延长和土壤缓冲性能的作用,低石灰用量(≤0.9 g/kg)对于提高土壤pH已没有明显效果,但其对降低土壤潜在酸效果显著,且大麦幼苗试验结果也表明生石灰的施入能显著增加大麦幼苗生物量。这说明土壤pH作为反映土壤酸度指标虽然有着测试简单、快速的优点,但仅仅只用pH来评估酸性土壤改良效果并不全面。5、验证了Ca(OH)_2滴定法计算石灰需要量的可行性。在研究条件下(pH3.9),施用生石灰改良后的土壤显著促进了大麦幼苗生长,且生石灰用量与土壤改良效果密切相关,以每千克土施用生石灰1.8 g(相当于4 t/hm~2生石灰用量)改良土壤酸性效果最佳,这与采用Ca(OH)_2滴定法计算出的石灰需要量1.76 g/kg相吻合。6、田间验证试验结果与培养试验一致。施用石灰能显著增加玉米产量,在pH 4.31(鹤峰县)和pH 5.03(利川市)的土壤条件下,以玉米产量为标准,石灰适宜用量分别为3000 kg/hm~2和2250 kg/hm~2,增产率分别为57.1%和9.1%。在pH5.03的田间条件下,施用石灰2250 kg/hm~2,种植一季作物后可使耕层土壤pH提高0.68个单位。
[Abstract]:In the past 80 's,90% of the farmland soil in China has different degree of acidification. In the past 25 years, the pH value of almost all the soil types in China has dropped by 0.13-0.80 units, and the average number of the soil has fallen by 0.5 units, and the acidification phenomenon is very common. Enshi Prefecture, Hubei Province, is located in the hinterland of Wulingshan area, and is affected by natural factors such as environment, climate and other factors, such as crop planting and fertilization, and the soil acidification of cultivated land is getting more and more serious. The problems of crop yield and quality decline induced by soil acidification are also developed and expanded, and become a new hidden danger to the steady development of the agricultural production in Enshi. in ord to provide a thorough understanding of that problem of soil acidification in the cultivated land in Enshi and the like, and to provide the basis for the development of the soil acidification control and the treatment countermeasure, Based on a large number of soil samples collected during the second soil general survey in China (1980-1983) and the evaluation of the quality of cultivated land (2010-2013), the changes of the soil pH value of the cultivated land in Enshi State were analyzed, and the present situation and characteristics of soil acidification in Enshi State were analyzed. The effects of different conditioning agents on the acid soil deacidification effect and the growth of the crops were discussed with the combination of the culture test and the pot experiment, and the effect of the application of lime and the appropriate amount of lime were further verified by field experiments. The results of the main research are as follows:1. In the last 30 years, the soil of Enshi State has a tendency to acidify, and the distribution of the soil pH is in the low pattern of the east and the west. In different areas, the soil pH of different types of cultivated land was decreased to a certain extent. During the second soil general survey, the average soil pH of the cultivated land was 6.5. After 30 years, the soil pH of the cultivated land was reduced to 5.6, the whole decline was 0.90 units, and the degree of soil acidification in the dry land was higher than that of the paddy field. mainly, the change of the structure and the ratio of the fertilizer (the proportion of the nitrogen and phosphorus and the potassium in the chemical fertilizer is severely maladjusted, the amount of the organic fertilizer is rapidly declining), and the high-yield crop is harvested and taken away with a large amount of salt-based nutrients (the fertilizer is used for fertilization and can not be effectively supplemented), 3. Different types of conditioning agents have different acid-reducing effects on the acid soil. The results of the one-year test showed that the effect of quicklime was the best, and that of 0.66 pH units compared with the control treatment, and the content of exchangeable Al in the soil decreased by 2.01 cmol/ kg. In that proces of the straw, although the soil acidity is not effectively reduced, the growth of the crop can be obviously promoted, and therefore, the straw treatment can also be used as an improved substance of the acid soil, and various regulating substances can be applied to the actual production to promote the growth of the crops. The appropriate evaluation index for evaluating the modified acidic soil of basic materials is the potential acid (total amount of soil-exchange acid, soil-exchange H + and soil-exchange aluminum). With the extension of the culture time and the effect of the soil buffering performance, the low-lime dosage (at the amount of 0.9g/ kg) has no obvious effect on increasing the pH of the soil, but the effect of the low-lime is obvious to the reduction of the potential acid of the soil, And the test result of the barley seedling also indicates that the application of the quicklime can obviously increase the biomass of the barley seedling. This indicates that the soil pH as a reflection of the soil acidity, although it has the advantages of simple and rapid test, but only using the pH to assess the effect of the acid soil improvement is not comprehensive.5. The feasibility of using the Ca (OH) _ 2 titration method to calculate the lime requirement is verified. Under the condition of the study (pH3.0), the soil with the modified quicklime significantly promoted the growth of the barley seedlings, and the amount of the quicklime is closely related to the soil improvement effect, and the soil acidity effect is optimized by applying the quicklime 1.8g (corresponding to the amount of 4 t/ hm ~ 2 quicklime) per kilogram of soil. This is the same as that of the lime required by the Ca (OH) _ 2 titration method.6. The results of field validation test are consistent with the culture test. The yield of the corn can be obviously increased by the application of lime. Under the soil conditions of pH 4.31 (Hefeng County) and pH 5.03 (Lichuan), the appropriate amount of lime is 3000 kg/ hm2 and 2250 kg/ hm2, respectively, and the yield is 57.1% and 9.1%, respectively. Under the field condition of pH 5.03, the soil pH of the plowing soil was increased by 0.68 units after the addition of the lime of 2250 kg/ hm2.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S156.2

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