Construction and Application of Soil Erosion Control and Circular Agriculture Mode in Hilly Red Soil of Southern China

[Objective] The paper was to construct soil erosion control and circular agriculture mode in hilly red soil of southern China, and analyze its application effort. [Method] The cause of soil erosion in hilly red soil of southern China and the reason for long-term treatment without remarkable effort were analyzed. On this basis, the key technology, economic benefit, ecological service function and carbon sequestration sink enhancement effect of various modes were further analyzed. [Result] The basic idea for comprehensive control of hilly soil erosion in southern China was as follows: the control of soil erosion was combined with modern agricultural production, in order to build "fruit(tea)-grass-livestock-methane" circular agriculture mode with comprehensive control of soil erosion; application effect analysis showed that the establishment of circular agriculture mode in southern hilly area to control soil erosion had remarkable effect, which could simultaneously meet the coordinated development of ecological, economic and social benefits. [Conclusion] This study established an effective mode suitable for soil erosion control and agricultural protection development in southern red soil mountain, which could drive the sustainable development of ecological restoration of mountainous area and rural agricultural economy.

Snstainable Land Use in Hilly Red Soil Region of South-eastern China

In the Present work, an integrated analysis of natural and socio-economic conditions in the hilly redsoil region of southeastern China is made by nieans of a Geographic Information System. Particular em-phasis lies on soil degradation and other adverse ecological and environmental effects of the prevalent andirrational land-use systems of mono-and valley-agriculture in the region. Moreover, taking into account thesimultaneous existence of enormous potentials and serious constraints and the high diversity and complexityof the biophysical and socio-economic environments, a set of strategies and counterineasures are also prc-posed for appropriate management of environmental resources, in terms of maintaining harmony betweenutilization and conservation of the natural environment, including 1) adjustment of the agricultural structureand optimization of ecological patterns of stereo-agriculture; 2) improvement and integrated exploitation ofthe low-yield lands and wastelands; 3) rehabilitation and conservation of soil and water resources; and 4)establishment of production bases of tropical and subtropical cash crops and fruits.

Soil and Water Resources and Land Sustainable Productivity in the Catchment Area with Intensive Management in Hilly Red Soil Regions,China

Taking an example of Majiayu Catchment Area (14.15 ha) in Taoyuan County of HunanProvince, the soil and water resources dynamics, fertility evolution characteristics andland productivity changing situation were studied. Fixed observation results from 1993to 2002 showed that pools covering about 15% of total area could store up 10% of surfacerunoff, keep 78.1% of eroded soil and 65.4% of lost nutrients. The yearly ratio ofinterception and evapotranspiration in land, storage in pools and drainage was 7:2:1,which ensured the resources and nutrients equilibrium and a benign recycle in thecatchment area system, and benefited the aquatic culture and helped to resist seasonaldrought. Moreover, the results showed that soil erosion modulus decreased significantly,equal to or lower than soil loss tolerance (≤500 tkm-2) in reddish yellow soil regions.Soil organic matter, total and available N content in sloping land, dryland and paddyfield increased steadily (>10%); water storage enhanced by more than 20% in sloping landand dryland in drought season; crop production increased by more than 20%; and productionof trees, fruits, tea and fish as well as land productivity increased yearly.

Response of Ecosystem Service Value Based on Land Use Changes and Analysis of its Driving Factors in Typical Hilly Region with Red Soil

The contribution rate of ecosystem service value variation was used to analyze the effects of land use changes on the changes of ecosystem service value in Xingguo County during 1996-2005.Grey integrated correlation was employed to explore the contribution level of the indicators such as total population,urbanization level,proportion of primary industry and investment of social fixed assets on ecosystem service value,and the correlation analysis was also carried out.The results showed that the ecosystem service value in Xingguo County during 1996-2005 mainly was woodland,and the decrease of woodland area was the major reason for the sustained reduction of ecosystem service value.With the further increase of market demand and the incentives of local government,the garden area rapidly increased during 2001-2005,and the influence degree of garden towards the changes of ecosystem service value was only second to woodland,ranking No.2.Four socio-economic indicators had different correlation degree with ecosystem service value during the different research periods.Total population,urbanization level and proportion of primary industry had high correlation degree with ecosystem service value,whereas the influence degree of various socio-economic indicators on ecosystem service value was equal with each other day by day.Urbanization level,investment of social fixed assets and total population had significant negative correlation with ecosystem service value,while the proportion of primary industry had positive correlation with ecosystem service value.

Ecological Effects of Land Use Patterns in Red Soil HillyRegion

Plant biomass and biodiversity, element accumulation and return, water loss and soil erosion, and changesin soil properties were studied for up to 10 years after conversion of sparse tree-shrubby grass land into thefollowing four land use patterns: masson pine (Pznvs massonzana Lamb.) land, beautiful sweetgum (Ltq-uidambar fomosana Hance) land, vegetation reservation land, and artificial mowing land. The annualbiomass production of the masson pine land was 5060 kg ha￣-1 being 4.9, 2.1, and 6.0 times that of the beau-tiful sweetgum land, the vegetation reservation land, and the artificial mowing land, respectively. Comparedwith the background values, the number of plant species for the vegetation reservation land increased by 10species after 10 years of land utilization, while for the masson pine and the beautiful sweetgum decreased by4, and for the artificial mowing land by 9. For masson pine land, total amount of N, P, K, Ca, and Mg neededfor producing 1000 kg dry matter was only 3.5 kg, annual element return through litter was 22 kg ha￣-1, bothof which were much lower than those of the other patterns. Vegetation reservation was an effective measureto conserve soil and water and improve soil fertility in the red soil hilly region. Artificial mowing arousedserious degradation of vegetation and soil. Some measures and suggestions for management and exploitationof the red soil hilly region such as masson pine planting, closing hills for afforestation, and stereo-agricultureon one hill are proposed.

Soil Fertility Self-development Under Ecological Restoration in the Zhuxi Watershed in the Red Soil Hilly Region of China

Current methods that utilize simple data or models to judge whether soil fertility can selfdevelop are not sufficiently rigorous. A new framework has been set up using catastrophe theory, laboratory experiment, field work, and 3S(Geographic information system, Global positioning system, and Remote sensing) to explore soil fertility catastrophe under ecological restoration, discriminate whether soil fertility can self-develop, and propose adjustment of ecological restoration measures in the Zhuxi watershed of Changting County, Fujian Province, China, which is a typical representative of the red soil hilly region of China. The results show that: 1) the soil fertility is obviously improved through the four ecological restoration measures, which impels soil fertility catastrophe. Among 89 soil samples, catastrophic soil samples and stable soil samples account for 26(29.21%) and 63(70.79%) of the samples, respectively. The four ecological restoration measures are listed in the order lowquality forest improvement > arbor–bush–herb mixed plantation > orchard improvement > closing measures according to the proportions of catastrophic soil samples. A typical soil sample in Bashilihe that can self-develop is selected as the criterion to judge the upper lobe and lower lobe of soil fertility in the process surface of the Cusp catastrophe model. Twenty-six(29.21%) were in the middle lobe, 10(11.24%) were in the upper lobe, and 53(70.79%) were in the lower lobe. The catastrophic direction of 26 catastrophic soil samples is to the upper lobe according to soil and water loss change as well as fieldwork. There is a significant positive correlation of Δ with soil and water loss change, and the lower soil and water loss relates to higher catastrophic probability. 2) Soil fertility self-development could be regionalized as "Soil fertility can self-develop" whose area was 12.74 km2(28.33%) distributed mainly in the leftmost and rightmost parts, "Soil fertility tends to self-develop" whose area was 11.63 km2(25.89%) distributed mainly in the middle part, and "Soil fertility cannot self-develop" whose area was 20.58 km2(45.78%) distributed mainly between the above two types. 3) There is no need to take ecological restoration measures and excessive human interference should be avoided in the future in regions of "Soil fertility can self-develop" and "Soil fertility tends to self-develop," and ecological restoration measures should be taken in region of "Soil fertility cannot self-develop." 4) We suggest withdrawal and implementation of ecological restoration measures should be incorporated into the evaluation criteria of ecological restoration to avoid misuse of funds.

Eco-geological environment quality assessment based on multi-source data of the mining city in red soil hilly region, China

High-intensity and large-scale resource development seriously threatens the fragile ecological environment in the red soil hilly region in southern China. This paper analyzes the eco-geological environmental problems and factors affecting Ganzhou, a mining city in the red soil hilly region,based on field survey and literature. The ecogeological environment quality(EGEQ) assessment system, which covered 11 indicators in physical geography, mining development, geological hazards,as well as water and soil pollution, was established through multi-source data utilization such as remote sensing images, DEM(Digital Elevation Model), field survey and on-site monitoring data. The comprehensive weight of each indicator was calculated through the Analytic Hierarchy Process(AHP) and entropy method. The eco-geological environment assessment map was developed by calculating the EGEQ value through the linear weighted method. The assessment results show that the EGEQ was classified into I-V grades from excellent to worse, among which, EGEQ of I-II accounted for 29.88%, EGEQ of III accounted for 32.35% and EGEQ of IV-V accounted for 37.77%;the overall EGEQ of Ganzhou was moderate. The assessment system utilized in this research provides scientific and accurate results, which in turn enable the proposal of some tangible protection suggestions.

Topsoil phosphorus signature in five forest types along an urban-suburban-rural gradient in Nanchang, southern China

Conversions from rural to urban land uses have the potential to greatly modify soil phosphorus （P） levels. Soils in shrubs, Masson pine forest, conifer and broadleaf mixed forest, evergreen broadleaved forest and bamboo forest in the mid-subtropical region along an urban-rural gradient in Nanchang City, southern China, were analyzed for total P and P fractions using the modified Hedley P sequential fractionation method. Results show that the topsoil total P and total exactable P concentrations were significantly higher in the urban area （0.71 g·kg^-1 and 378.50 mg·kg^-1, respectively） than in the suburban （0.30 g·kg^-1 and 150.74 mg·kg^-1, respectively） and rural areas （0.31 g·kg^-1 and 147.38 mg·kg^-1, respectively） （p〈0.05）. Among the five P fractions of resin-P, NaHCO3-P NaOH-P, Sonication-P and HCI-P, the relative abundance of HCl-P in urban forest soils （36%） was the highest and also significantly higher than in suburban （8%） and rural soils （6%）, while NaOH-P was the dominant form in suburban （41%） and rural soils （50%）. Phosphorus accumulation in the urban soils could affect the cycle of P in urban forest systems, particularly the HCl-P fraction that might rapidly enrich aquatic systems in urban areas.

Effects of soil and water conservation and its interactions with soil properties on soil productivity

The effects of soil and water conservation （SWC） on soil properties are well documented. However, definitive and quantitative information of SWC and its interactions with soil properties on soil productivity is lacking for hilly red soil region of southern China. Experiments were conducted in the hilly red soil region of southern China for seven years in three rtmoffplots, each of which represented different SWC forest-grass measures. Principal component analysis and multiple regression techniques were used to relate the aboveground biomass （representing soil productivity） to soil properties. Based on the final regression equations, soil organic carbon content （Sot） is significantly correlated with soil productivity under the condition of forest-grass measures, whereas pH value and cation exchange capacity （Cee） are the main factors for soil productivity without SWC. Therefore, SWC plays an important role in sequestering Soc and improving soil productivity.

A Study of the Qianyanzhou Mode in a Subtropical Red Soil Hilly Region of China

Qianyanzhou is located in the heart of Jitai Basin in Guanxi town,the county seat of Taihe county in Jiangxi province.Qianyanzhou has a subtropical humid climate and exemplifies the geographic and geomorphologic characteristics of red soil hilly regions in southern China.In the early 1980s,to control soil and water loss and problems with grain yields,Qianyanzhou's researchers proposed an innovative,comprehensive stereoscopic ag- riculture development mode known as the 'Qianyanzhou mode'.This mode included a forest-livestock-food ecosystem,a forest-fruit-economy ecosystem,and a land-water compound stereoscopic system,all located within a watershed.In the Qianyanzhou mode,soil and water loss were completely controlled,thereby promoting environmental conservation and economic development.The state and the society as a whole supported this mode thanks to its far-reaching social impact.In the 21st century,given new societal concerns and continuing economic development,Qianyanzhou mode has been restructured as two ecosystems of forest-fowl and planting-raising circular economies at landscape level,based on an increase in vegetation coverage from 4.3% to more than 80%.These improved modes can significantly enhance the ecosystem,reduce poverty,and to promote the construction of local ecological civilization.This study introduces the Qianyanzhou mode and summarizes its characteristics in different phases.We hope that the information in this study supports improvements to and promotion of the Qianyanzhou mode.We believe the Qianyanzhou mode can play an important role in efforts to modify the agriculture industrial structure,alleviate poverty,and construct ecological civilization.

Development of a surface modeling method for mapping soil properties

High accuracy surface modeling （HASM） is a method which can be applied to soil property interpolation. In this paper, we present a method of HASM combined geographic information for soil property interpolation （HASM-SP） to improve the accuracy. Based on soil types, land use types and parent rocks, HASM-SP was applied to interpolate soil available P, Li, pH, alkali-hydrolyzable N, total K and Cr in a typical red soil hilly region. To evaluate the performance of HASM-SP, we compared its performance with that of ordinary kriging （OK）, ordinary kriging combined geographic information （OK-Geo） and stratified kriging （SK）. The results showed that the methods combined with geographic information including HASM-SP and OK-Geo obtained a lower estimation bias. HASM-SP also showed less MAEs and RMSEs when it was compared with the other three methods （OK-Geo, OK and SK）. Much more details were presented in the HASM-SP maps for soil properties due to the combination of different types of geographic information which gave abrupt boundary for the spatial varia- tion of soil properties. Therefore, HASM-SP can not only reduce prediction errors but also can be accordant with the distribution of geographic information, which make the spatial simula- tion of soil property more reasonable. HASM-SP has not only enriched the theory of high accuracy surface modeling of soil property, but also provided a scientific method for the ap- plication in resource management and environment planning.

Assessing effects of land use and land cover changes on hydrological processes and sediment yield in the Xunwu River watershed, Jiangxi Province, China

The effects of land use and land cover changes on hydrological processes and sediment yield are important issues in regional hydrology.The Xunwu River catchment located in the red soil hilly region of southern China has experienced drastic land use changes in the past 30 years,with orchard increases of approximately 42%and forest decreases of approximately 40%.These changes have resulted in some alterations of runoff and sediment yield.This study aims to evaluate effects of land use/land cover on runoff and sediment yield in the Xunwu River catchment.The SWAT model(Soil and Water Assessment Tool)was used for runoff and sediment simulation,and the results met the requirements of the model acceptance based on evaluation statistics of R^(2)(the coefficient of determination),PBIAS(percent bias),and NSE(Nash-Sutcliffe efficiency).Four land use scenarios representing the gradual expansion of orchards in the past 26 years were developed for assessment of hydrological processes and sediment yield simulation.As a result,both runoff and sediment yield were changed insignificantly with decrease rates of 1.84%and 5.29%,respectively.In addition,surface runoff accounts for the largest share of the runoff components,but the lateral flow changed more than other runoff components with a decrease rate of 10.96%.The results show that orchard expansion does not reveal severe water and soil loss.This study can contribute to the rational utilization of land and water resources in the red soil hilly area of southern Jiangxi Province.