Abstract:Based on an investigation into productivity，soil water and soil nutrient content of croplands,artificial grasslands (Medicago sativa)and shrub forests (Caragana korshinskii )，and natural grasslands in the northern region of Shaanxi Province，the productivity differences among different vegetation types and territories are discussed comparatively，and the reasons for these differences are analyzed.The results show that the productivity of croplands(foxtail millet) was far better than that other plants or vegetation types,but roduction stability is relatively poor in these systems.Productivity in artificial grasslands，shrub forests and natural grasslands is lower than in croplands,productivition stability，community biodiversity index and soil nutrient content of natural grasslands are the best among the surveyed plants (or vegetation types).It is proposed that besides water，low soil nutrient content and short of reasonable running also limit plant productivity improvement.To evaluate the productivity and longterm adaptation of different plants to the environment and offer guidance to the construction of vegetation systems in the region,long-term research areas or provisional survey study spots should be founded.

Abstract:The effect of Melilotus officinalia on improving degraded soil is studied according to the change in nutrient content of soil after planting. The results show that planting Melilotus officinalia can increase soil organic matter，total N，hydrolytic N，total P，and available K significantly，but decrease available P and total K.The reason for the latter decreases is that Melilotus officinalia needs phosphate fertilizer and potassium fertilizer to satisfy its growth.Therefore，during the growth of Melilottts officinalra，phosphate fertilizer and potassium fertilizer should be applied reasonably in order to boost nitrogen levels in the soil.This biotechnology technique functions to improve saline alkaline soil and increase the fertility of soil.The experiment indicates that Melilotus officinalia is an excellent kind of pasturage for improving the degraded soil in arid and semiarid regions.

Abstract:With the methods of combining macroinvestigation with microexperimentation，and test analysis with site observation，land degradation caused by soil and water loss on slope fields is studied in hilly and gully areas of the loess plateau.The results show that soil and water loss on slope fields not only brings about surface runoff loss and topsoil fertility decline，but also causes the soil nutrient loss，soil physical property damage and weakened soil infiltration capacity.The direct result of soil degradation is the reduction of land productivity.The impacts of soil and water loss in different slope fields under different crops are productivity losses of between 21.9%and 80.0%.

Abstract:Six plots of simulated speedway slope with different gradients are studied.Soil and vegetation measures are made to study the mechanism and characteristics of rill development on simulated slopes under rainfall and flow scouring.The results show small rills develop on sandstone slopes planted with lawn of much cover during the final term of rainfall.However。rills develop obviously and with complex shape on loess and gravel slopes planted with shrubs.The maximum width and depth of rill is 18.4 and 16.5 cm respectively.The combination of engineering measures and vegetation measures is the best choice to protect speedway slopes.

Abstract:There are a lot of salinized lands across all counties in Hexi Corridor.This kind of lands could be improved and used properly.The experiments on planting turf in the saline-alkali lowland have been done in the northeastern suburban development zone of Zhangye City.The high quality turf lawn in the severe saline-alkali land could be established and mitigate the status of land salinization by the burying the hidden pipe of two layers and fertilizing phosphate gypsum in soil，which can induce growth of halophilous weeds and remove the weeds as well as employing the improved irrigation.

Abstract:Taking the typical research region of Yangou，a small watershed in an eroded red soil area of south China，as an example，an evaluation of land resources based on GIS and GPS technologies，employing fuzzy mathematics and index methods，has been undertaken.The evaluation assigns 55.1% of the land area in the watershed to five grades，with general land quantity being low in the area.Soil erosion is the main resource limiting factor，and adoption of engineering measures，planting measures and combinations there are of importance to the reasonable utilization of land resources and to the enhancement of soil fertility in the region.Application of GIS、GPS and fuzzy mathematics methods is scientifically sound and feasible for the evaluation of the land resources at the scale of small watersheds.This research expands the field for this type of land resources evaluation.

Abstract:Landslide and collapse are two basic types of bank destruction occurring in medium and small-sized reservoirs in the northwestern region.Based on numerous site investigation，the relationship between the bank stability and the characteristics of medium and small reservoirs is studied，and the destabilising mechanism of reservoir banks is analysed.Calculation methods for several types of evaluation of loess bank slope stability are proposed.It is shown that the results of the calculations agree with reality.

Abstract:The connection between different plant systems and runoff from sloping fields was studied and discussed for the periods 1994-1996 and 2001-2002.These data indicated that farmland runoff increased markedly after barren sloping field was exploited.There were differences in effect on runoff of different plant systems.From 1994 to 1996，relative runoff under different plant systems was:paddy-wheat>maize-buckwheat-barley> peanut-buckwheat> red potato-wheat.During 2001-2002，the relationship was:peanut>maize-radish i peanut-cole>fruit tree-peanut Ontercrop).Runoff under a solop plant was greater than that under a rotatation system，and that under a rotatation system was greater than that under a fruit growing intercrop system.Also，higher plant coverage resulted in the less runoff.Managing measures on farm and the characteristics of the plant systems used were key factors affecting runoff.

Abstract:With the support of GIS technology，the SCS (soil conservation service)model was selected to model runoff of the upper watershed of the Luohe River(a tributary of the Yellow River) using a 1:250 000 DEM and a 1，1 000 000 DEM.By comparison of the simulated annual average runoff yield from through to 2000，it was found that a higher runoff volume was obtained using the 1:250 000 DEM.There are marginal differences in area，elevation，slope，channel length，and drainage network between the DEMs of different resolution，but there is a greater difference in slope change.Through analysis of the sensitive parameter CN of the SCS model，the sensitivity of runoff modeling to DEM resolution is described from the perspective of slope change.

Abstract:Rainwater harvesting and use is a direction for sustainable development of dryland farming in the hill and gully area of southern Ningxia Hui Autonomous Region.According to the area's natural，social and economic characteristics，and in combination with the spread of applied agricultural technology，five kinds of integrated models of rainwater harvesting and use technology are set forth.These include:(I)integrated use model of rainwater collected in watersheds;(2)grassland and forestry construction use model of rainwater collected form slope land;(3)field farmland irrigation supply use model of rainwater collected from road surfaces;(4)courtyard guard plant use model of rainwater collected from roof and court;and(5)high efficiency dry field use model of rainwater collected from microcollection engineering.The benefits of the models are analyzed from results obtained at the national demonstration district of rainwater harvesting and use.which is located in Wangwa demonstration district of Pengyang County in southern Ningxia region of China.

Abstract:The specialties and conditions of engineering a new soil consolidator are introduced simply.The capability of the soil consolidator to control channel seepage is demonstrated by experimental information of the nature of compaction，compressive strength，water stabilization and freeze-thaw resistance.The conclusion reached is that in establishing freeze resistance，the soil consolidator is limited in controlling channel seepage.This study provides a reference for others engineering soil consolidators.

Abstract:Liquid film is a new kind of soil conditioner and compartmentalisation is a new method for turf building.Experimentation shows the effect on soil water，soil temperature and seedling growth in an arid environment of liquid film，compartmentalisation and their combination.The results indicate that fiber compartments and cotton compartments used together with liquid film can improve soil water conservation，but reduce considerably maize seedling growth rates.Liquid film alone showed the best results，improving soil water conservation and soil temperature and enabling a higher seedling growth rate in an arid environment than the other methods.Liquid film warrants further study and application as a new measure to preserve soil moisture and enhance seedling growth in arid environments.

Abstract:A study was conducted on the loess plateau to find ways for hilly road erosion control.After evaluating the soil loss caused by road building in different regions，the road erosion type and difference in topographical succession are analyzed.With the consideration of drought-resistance of vegetation species and sources of species suitable for growing on roads，the criteria for designing a road erosion controlling system including biological measures are suggested.Suitable shrub and grass species are also suggested.

Abstract:Soil salinization is a serious problem in Yanqi basin，Xinjiang Wei Autonomous Region、and the agricultural development and the ecological environment are threatened.Based on analysis of the chemical composition of salt-affected soil and statistical analysis of its spatial distribution，it is concluded that:(1)the salt type involved in soil salinization is chlorinate-sulfate and about 60% of land is strong salinizated and saltier;(2) soil salinity is greater in natural areas than in farmland areas;(3)soil salinity increases from the fringe of the torrential fan to the shore of salted lake.In irrigated areas，soil salinity changes seasonally and decreases as a whole because of irrigation and drainage.The reasons for soil salinization include natural factors and human activity.Water-saving irrigation，rational groundwater exploitation and improved irrigation and drainage systems are effective measures to control soil salinization.

Abstract:There are affluent water and thermal resources in latored soils of south subtropical hilly area，which has an advantage to develop tropical fruit and vegetables like litchi，longan，banana，mango and so on.An introduction of natural conditions of south subtropics，superiority of south subtropics in Guangdong Province and characteristics of latored soils region is presented in this paper.But the soil water storage capacity and the available water content are very little，combined with low unsaturated hydraulic conductivity and hydraulic diffusivity because of the restriction of climate factors.Some biological or engineering technical measurements of regulating and managing soil moisture properly are advised to improve soil and prevent or lessen soil evaporation.

Abstract:Farmlands are the largest and most important parts of the oases in the middle reaches of the Heihe River，accounting for 84.2% of the total area of oases in the region.Shelterbelts of farmlands constitute the principal ecological conservation system of the oases.Only through better development of shelt belts can the coverage of forest in the oases be greatly enhanced，and thus the ecological environment of the oases in this region improved.The realistic pathway for further development of farmland shelt erbelts is to construct multispecies shelt erbelts，to improve regeneration of shelt erbelts and to explore water-saving technologies.

Abstract:A granite based soil region is distributed widely in the drainage area of Dongting Lake.Intrinsic characteristics of granite，special weather conditions and the relationship between humans and land in the Dongting Lake drainage area make this soil region one of the most seriously affected by soil erosion and causes very bad environmental，social and economical results.In the granite area.topography is steep，weathering is rapid，the layer of weathering is very deep and the soil is very easily eroded away.With inherent and external erosion forces acting together，it is possible to relate a time sequence to the features of every weathering layer.On the basis of observations to the granite bedrock，the authors indicate the soil erosion region in different areas，suggest the time sequence characteristics of soil erosion and reveal the temporal and spatial differences between soil erosion occurrences.To manage the extent of the study，the authors first try to classify the regional differences in granite soil erosion within wetter areas.

Abstract:The conversion of farmland to forestland or grassland on the Loess Plateau is a challenging ecological project.Much attention should be intensively focused on rational plan and extensive argumentation on the program and the problems on slow orderly progresses，low survival rate of tree seedlings in the afforestation and less scientific and technological support in the program because the program of conversion of farmland to forestland or grassland was launched on large scale and carried out quickly on the Loess Plateau，and there were few experiences on fulfilling this program.Based on the current situation and investigation results on the processes of this program，the presented suggestions on this program are as follows:manifesting the significant roles of conversion of farmland to forestland or grassland in ecological improvement，intensifying the practicality of the policy on carrying out eco-environment improvement and comprehensive harnessing in the farmland-converted area，strengthening the integrated measure execution in terms of preventing the recession of farmland conversion，supporting to confine grazing in order to promote restoration of natural vegetation according to specific policy issued by government，and paying attention to the food supply risk and the corresponding countermeasures.

Abstract:The status of desertification and the significance of carrying out conservation tillage in the north of China are analyzed in the present paper.Some ideas on technical measures and necessary systems of preventing farmland desertification are proposed based on the ecological principals.

Abstract:Songnen Plain is an important productive base of commodity grain in China.Sustainable social and economic development of this region has been seriously restricted by water shortage and irrational utilization.Unreasonable utilization of water resources has many impacts，such as drawing down groundwater levels，shrinking wetland areas and inducing secondary saline alkaline soil，etc.According to time-space distribution and utilization status of water resources，eco-environment water demand and water supply for industry and agriculture，three strategies for sustainable use are put forward:(1)water must be allocated to the eco-envi-ronment in order to improve the quality of the regional ecoenvironment by，for example protecting and reconstructing wetlands and managing groundwater levels to prevent waterlogging，salinisation，alkalinization and desertification;(2)water-saving practices must be developed for agriculture，industry and society，to utilize water effectively and efficiently;(3) water resources should be collocated in space and time to enable optimal water use and management and to ensure concurrent and stable development of the ecoenvironment，society and the economy.

Abstract:Drawing lessons from the latest accomplishments at home and abroad in comprehensive evaluation of regional sustainable development and according to AHP(Analytical Hierarchy Process)，this evaluation was designed，to include assessments of economic development level. social development level，resource and environmental security level，sustainable development capacity and system development coordination. Accounting for the regional features of the Baota District of Yan'an City，the evaluation of regional development during the period from 1992 to 1999 shows the sustainable development level of Baota District increased steadily.However，recently the region has experienced a weaker state and system of development.