Study On Agricultural Factors Of Relative Safe Flow Of The Yellow River From The Eastern Han Dynasty To The Tang Dynasty

The safe flow of the Yellow River from the Eastern Han Dynasty to the Tang Dynasty is an important issue in the academic circles and has attracted wide attention.For a long time,scholars from different fields have carried out extensive discussions on the causes of the occurrence of the Anliu and Anliu currents in the Yellow River from the Eastern Han Dynasty to the Tang Dynasty.Generally speaking,most scholars believe that the Yellow River from the Eastern Han Dynasty to the Tang Dynasty has a situation of safe flow,which is a relatively safe flow.However,academic circles have different opinions on the causes of the relatively safe flow of the Yellow River from the Eastern Han Dynasty to the Tang Dynasty,which need further in-depth demonstration.As far as the existing research is concerned,the relatively safe flow of the Yellow River from the Eastern Han Dynasty to the Tang Dynasty is the result of the comprehensive effect of multiple factors,and it is not credible to emphasize the decisive role of single factor.Therefore,from the perspective of agricultural history,combing the agricultural factors of the relatively safe flow of the Yellow River from the Eastern Han Dynasty to the Tang Dynasty with the relevant achievements of modern soil and water conservation will undoubtedly help to promote the related research to go deeper.Firstly,the succession of agriculture and animal husbandry in the middle reaches of the Yellow River(especially the mountain,shaanxi valley and the upper reaches of jing,wei and beiluo river)has a significant impact on the downstream river flood.Specifically,the reduction of agricultural production mode and the expansion of animal husbandry production mode in the middle reaches of the Yellow River from the eastern han dynasty to the tang dynasty were beneficial to the reduction of soil erosion and the reduction of river damage in the lower reaches.During the tang and song dynasties,the agricultural development of the northern nomads(liao,jin and xixia)made the loess plateau area the forefront of the confrontation between the song dynasty and the ethnic regime,which greatly intensified the ecological and environmental pressure in the region.Therefore,during this period,the soil erosion in the middle reaches of the Yellow River was also aggravated,which may be an important inducement for the unprecedented river diseasesin the northern song dynasty and later.Secondly,from the perspective of agricultural production mode,the changes of farming mode and planting structure in the middle reaches of the Yellow River also have an impact on the flood in the lower reaches of the Yellow River.In terms of farming methods,cattle farming was more likely to cause soil erosion than hoeing in ecologically fragile areas.During the Western Han Dynasty(especially after the Emperor Wudi Dynasty),state behavior promoted the implementation of cattle farming in the middle reaches of the Yellow River and other border counties,while the cattle farming area in the Eastern Han to Tang Dynasty decreased significantly compared with the Western Han Dynasty,which was conducive to soil and water conservation and the reduction of river disasters in the lower In terms of planting structure,wheat has better soil and water conservation effect than millet.If the number of wheat plants per unit area is more than that of millet,it is easier to play the role of close planting.Similarly,wheat field has better water permeability than millet field,which is conducive to underground infiltration of precipitation.In addition,wheat can cover bare soil in winter,which is conducive to reducing soil erosion.The history of the Western Han Dynasty recorded that "the custom of Guanzhong is not good for wheat cultivation",the wheat cultivation area in the middle reaches of the Yellow River is limited,and the status of wheat cultivation from the Eastern Han Dynasty to the Tang Dynasty has been continuously improved,and by the middle of the Tang Dynasty has been equivalent to that of millet cultivation.The increase of wheat-growing areas and the corresponding decrease of millet-growing areas in the middle reaches of the Yellow River from the Eastern Han Dynasty to the Tang Dynasty are conducive to soil and water conservation and the reduction of river disasters in the lower reaches of the region.Thirdly,from the perspective of crop planting site selection,as winter wheat sowing at the end of autumn and early summer harvest and growing period can avoid the flood season of the Yellow River,people in the lower reaches of the Yellow River in the western han dynasty were greedy for fertile soil and used the disaster prevention effect of winter wheat "cultivation on the embankment" to plant winter wheat in the river and its flood detention area,contributing to the occurrence of Yellow River flood.The phenomenon of indiscriminate reclamation and construction in the lower reaches of the river from the eastern han dynasty to the tang and huang dynasties was controlled,which was conducive to the emergence of the relative amenity of the Yellow River.Finally,the ancients believed that "to control the land is to control the river".Therefore,active agricultural activities were beneficial to the reduction of the Yellow River flood,which was undoubtedly one of the reasons for the relatively peaceful flow of the Yellow River from the eastern han dynasty to the tang dynasty.