Study On Formation Process Of Soil Till Layer In Guanzhong Plain

Research on anthrosols in China emerged in the1960s, the anthrosols are mainly divided into the orthic anthrosols and stagnic anthrosols, and the two types of anthrosols are resulted by long-term agricultural production activities. More research focused on the existing arcble land based on soil science perspective, but the research on the relationship between the formation of anthrosols and agricultural activities such as farming, accumulation, fertilization, irrigation and so on in historical period, and the specific changes of soil under the influence of these activities is lacking. The Loutu soil in Guanzhong plain is typical anthrosols has obvious regional characteristics, the deep plough layer resulted by the influence of human activities is main different from natural soil. Through historical literature analysis and soil profile survey, the historical evolution process of soil naming and classification in Guanzhong area, soil structure, soil texture, soil moisture and so on, and the influence of cultivation, fertilization, irrigation activities on the formation of soil plough layer, and regional difference of Guanzhong soil plough layer were studied in this paper.The cognitive process of soil followed by agricultural production activities, and was promoted each other in the process of soil utilization and improvement. Naming and classification of soil of Guanzhong plain in the history has obvious historical stages, and are mainly divided into the following four stages:the soil classification in accordance to appearance characteristics and texture of soil in the early Qin period, the soil description based on soil production features from Qin and Han dynasties to Ming and Qing dynasties, the soil classification combined with soil production properties and soil genetic classification in modern times, as well as the soil taxonomy application and the emergence of soil name such as agricultural soil, tillage soil and anthrosols in the period of the People’s Republic of China.The Loutu soil in Guanzhong areas has the profile structure composed of upper artificial heaped slaking layer and lower natural soil layer. The upper artificial heaped slaking layer is resulted by the action of natural newly accumulation of dust and applying mixture of soil and manure in human agriculture activities. Heaped slaking layer can be divided into multilayer structure of modern plough layer, ancient slaking layer, and ancient plough layer. In Guanzhong plain, the loess, the Lutu soil, the Loutu soil were cultivated soils in different areas and the different historical periods. The main impetus improving soil environment, creating the fine structure of soil plough layer come from historical farming activities such as the use of production tools, management way of field, farming technique, crop type selection, etc. With agricultural advancements, the frequency and intensity of the disturbance to soil plough layer gradually is increasing, and is more close to the upper soil layer, soil ripening degree is higher and artificial features is more obvious.The application of mixture of soil and manure in Guanzhong plain is a key link in the process of soil plough layer. During the process of improvement of soil fertility in Guanzhong area in the ancient, fallow, grass fertilizer, silkworm excrement, human and animal feces, old wall soil,green manure planting were the main ways. From Han to Ming dynasty, the fertilization way of mixing soil and manure was always there in agricultural production process, but showed a greater inclination of planting way and the choice of crops. The applying of mixture of soil and manure only in the planting use Qutian method and the planting of economic crops such as fruits and vegetables. From Qing dynasty to the Republic of China, the significantly improvement of multiple cropping index need boosting soil fertility, the process of fertilizer collection and application obviously enhanced, so that soil cumulic epipedon fastly was forming in this period. At the same time of artificial pile, dust has been dropping, but with the development of agricultural level and the improvement of land productivity, the mixture of soil and manure to form the parent material of soil plough layer were gaining a higher proportion.In Guanzhong plain, the greater impact of water conservancy in addition to water supplies is that river sediment from irrigation was involved in the formation of soil plough layer and ripening process, and it promoted the improvement of saline soil, swamp soil, wet soil and the formation of soil irrigation deposition layer, the performance is very obvious in eastern Guanzhong plain. Creating plough layer through deposition, pressuring salt and washing through irrigation were the main ways of soil improvement, soil properties of different irrigation area is the key factors decided to deposition effect. In between the Jinghe river and the Shichuanhe river, the small distribution area of saline soil and the low degree of salinization were basic guarantee of significant effect from irrigation deposition, is also advantageous for the sustained development of irrigated activities in the Jinghe irrigation area. In between the Shichuanhe river and the Luohe river, the east section of zhengguo canal and Longshou canal are failed to sustainable use, it showed that the effect of soil improvement affected by the natural factors such as topography, geomorphology, soil and irrigation and drainage technology was greatly restricted in historical period. The Jinghe river, Weihe river, and Luohe river in Guanzhong plain is silt-carrying river. The formation of irrigation-silted soil and filling and silting thickness were positively correlated with the sustainability of irrigation activities. The distribution area of irrigation-silted soil is wider and filled silt layer thickness is larger in the Jinghe river irrigation area that has long irrigation history. The another important feature of irrigation-silting soil formation in Guanzhong plain is that using farming technologies marked by plow, harrow and applying mixture of soil and manure participated in the soil formation, the irrigation sedimentation and heaped process are main affecting factors to the formation of soil plough layer.The Youtu soil in western Guanzhong, the Loutu soil in eastern Guanzhong, the Lichatu soil and paddy soil in the south of the Weihe river are major artificial soil types. Climate, topography, parent material are the main factors of the formation of soil, and is also the main factors restricting and influencing the way of agricultural production. In comparison, the greater ripening degree of Youtu soil in western Guanzhong is mainly due to the better hydrothermal conditions and long history of cultivation, and uniform loess parent material composed of dust sedimentation and mixture of soil and manure, and the lower ripening degree of Loutu soil in eastern Guanzhong is mainly due to drier climate and soil parent material constantly added river sediment. The ripening degree of the red Youtu soil and the red Loutul soil on loess platform is lower than the black Youtu soil and black Loutu soil; which is mainly related to the superior production conditions such as higher population density, better irrigation, crop diversity and manure transport convenience terrain on the terrace plain.