Abstract:There is a good correlation between vegetation typies and loess thicknesses in the loess Plateau with semiaridclimate. Forests are distributed in rock and thin loess regions in the Loess Plateau. Due to the higher porosity ofloess,related to effective soil moisture,precipitation is not able to penetrate into the loess deeply. Soil moisture in thesurfasce horizons losses severely under the semiarid climate conditions. Rehabilitation of vegetation may be by usingtrees or shrubs with deep roots in the rock and thin loess regiong and by using grsses or shrubs with shallow roots inthe thick loess region in the platesu.

Abstract:Facfors of more mountains and less farmland, more population, poor economics and bad ecological environmenthindered economic development in mountains and hills of the subtropic zone in China. In course of the developmentwe must coordinate the relationship among mountains, forest,Land and man;adjust the relationship of grain-for-est and animal husbandry-sideline and fishery production: improve the environments of production-live-ecolo-gy; raise the ecological-economic-social benefits.

Abstract:Based on ″net income per capital″,a quantilative index of well-to-do and on the investigation in 315 mainsmall watersheds of the first phase of the the project of four key controlling areas in the Yellow river watershed.The results show that control of small watershed has made the first progress on a well-to-do road.However therestill exist some problems in degrees after 10 years ,The auther analyses the reason caused this situation and consid-ers that main causes are land use construction and industrial construction.

Abstract:The economic problem study is very significance in the research system of soil and water conservation. The au-thor analyses the conceptions of economic problems study in soil and water conservation.

Abstract:This paper ishsed on the field observed data to study the effects of natural rainfall factors and slope steepnesson sheet erosion. The results show that the index of EI_(30) (prduct of kinetic energy and maximum thirty-minuteintensity of rainfall)which reflected the characteristics of rainfall and the potential energy of runoff which is a com-prehensive index of including rainfall factors and topographical factors are important factors on affecting the sheeterosion. The sheet erosion models with clear physical conceptions are presented by analysing, and these can be pro-vided analytical basis for establishing prediction models of soil erosion on sloping land.

Abstract:Based on the field test of saturated D-optimal designs with a匆uare,This paper deals with the response equa-tion of N and P fertilizer,on Spring Whest in three different yild ecosystem in Shanghuang experimental station.The mathmatic model of fertilization with different adaptability has been established,The main effect and mutualeffects of N and P fertilizer have been analized and the optimum of fertilizer required has been caculated according tothe model. fertilizer amount applied and the optimum ratio of N and P of crops grown in low terrace have been cacu-lated as an example.

Abstract:An extensively occurring and calamitous proress of gravitational erosion causing the red weathering mantleslope to fall in is known as slope disintegration or slope failure. Usually. it can be divided into following forms ac-rnrding to its shape features. a. linear disintegration. b. forked disintegration. c. gourd ladle-like disintegration. d. dustpan-like disin-tegration. e. badland disintegration. The change processes of its shape has undergone water erosion stage first and then gravitational erosion. Theerosion processes of disintegration include the falling back of the gull walls cespacially the gully heads and the re-erosion of the colluvial deposits. And its erosion mechanism is closely related to the following situations; a. mechanical componment of the red erath and its changes with water action. b. types of the crack in the redweathering mantle. c. impact of storm events. d. impact of the elements of a hill.

Abstract:Based on pot experiment ,Proso yield response to different droughts in five growing periods was analysed,thewater deficits index( ri )and the drop productivity index(Ri)and the preductivity response index(Kyi)were ob-tained. The results show that:grain-filling stage was the most sensitive stage response to drought.When drought oc-cured in the stage,the daily drop product was the highest and the water use efficiency was the lowest. It is also inthis stage that irrigation is the most effective. In shooting and anthesis stage,the reaction between yield and droughtis very little,The evaptranspiration(ET)in tilling stage is the highest,about 28.6%of total ET. The normal evap-transpration in pot experiment was up to 185mm and in droughts was 167mm,and mean WUE was 0.5Kg/mm inthe experiment of drought treatment.ri,Ri,Kyi were used to foretell the proso yield.The estimated result was veryclose to the real yield, also the biomass response to drought was anslysed in the paper.

Abstract:The area of loess plateau covers 45 per cent of total area of shaanxi province .the disaster of landslide and col-lape occors frequently at the slope of loess plateau, whicL produces serious damages to the daily life of the local peo-ples and national economic development each year. The chracteristics of topography and geology of loess plateauhave been discussed, formation factor and deformation mechanism of landslide have also been analysed. The au-thors orooosed strateeies to orerent landslide in loess nlaleau.

Abstract:In order to make full use of the barren hills and to speed up the development of econmy in hilly region，we be-gan the experiment of cultivating pomegranate in hilly region in 1990. During the following four years, we success-fully . finished the experiment. We not only brought forth new ideas of cultivating technigues of high qualitypomegranate. finding out the reason why some pomegranate flowers can not bear fruit and the way to increase therate of bearing fruit .but also we proved that the cultivation of pomegranate is helpfui to conserve water and soil inhilly region. Now the total area of hill pomagranate has increased to 1 .800 hectare in our city，and the output offresh fruit is 632300kg in 1993. The social economic benefits is 3. 072 million yuan.

Abstract:This paper has discussed the situation and damage of soil and water losses in Luanping county in hebei provinceand reviewed the way how to move towards correct road of comprehensive control of small watershed in the pastforty years. The model of control and development of comprehensive control of mountains,rivers,fields forestry androads.of stereoscopic development of forestry fruit tree,grain.grass.medicinal plants, and of organicunite mergingeconomy,society and ecology has been explored. In recent years,thirteen small watersheds by comprehensire controlhave acheived initialy gratifying effects of economy,ecolo}y and society etc.