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Topography is a critical factor that determines the characteristics of regional soil formation. Small-scale topographic changes are referred to microtopographies. In hilly mountainous regions, the redistribution of water and soil materials caused by microtopography is the main factor affecting the spatial heterogeneity of soil and the utilization of land resources. In this study, the influence of microtopography on pedogenesis was investigated using soil samples formed from mudstones with lacustrine facies deposition in the middle of the Sichuan Basin. Soil profiles were sampled along the slopes at the summit, shoulder, backslope, footslope, and toeslope positions. The morphological, physicochemical, and geochemical attributes of profiles were analyzed. The results showed that from the summit to the toeslope, soil thickness increased significantly and profile configuration changed from A–C to A–B–C. The total contents of Ca and Na decreased at the summit, backslope, and footslope, while the total contents of Al, Fe and Mg showed an opposite trend. On the summit and shoulder of the hillslope, weathered materials were transported away by gravity and surface erosion, exposing new rocks. As a result, soil development in these areas was relatively weak. In flat areas such as the footslope and toeslope with sufficient water conditions, the addition of weathered components and the prolonged contact between water, soil, and sediment led to further chemical weathering, resulting in highly developed characteristics. Microtopography may influence physicochemical properties, chemical weathering, and redistribution of water and materials, causing variations in pedogenic characteristics at different slope positions. [ABSTRACT FROM AUTHOR]

It is of great significance to determine soil aggregate stability in predicting agricultural production conditions and soil erosion risk. However, the problem exposed in the process of evaluating soil aggregate stability cannot be ignored: Can the effects of different mechanisms on the degree of soil aggregate breakdown be distinguished by selecting ethanol and water as dispersion media? Based on this question, natural soils with a gradient in soil textures of silty loam to loamy clay were used as the test materials. Deionized water, ethanol and hexane were employed as soaking solutions to quantitatively analyze the extent to which the aggregates were dispersed in static disintegration experiments. The results suggested that the soil hydrophilicity (SH) of six soils with a texture gradient were >1 by comparing the aggregate breakdown index (ABI) of soils undergoing ethanol and hexane dispersion. This indicated that the hydrophilic group (-OH) contained in ethanol interacted with the hydrophilic surfaces of the soil particles. Therefore, the soil hydrophilicity (hydration) should be determined by comparing the ABI values undergoing hexane and water dispersion. From silty loam to loamy clay, the average contribution of hydration to aggregate fragmentation decreases, and the process of aggregate breakdown with different textures is characterized by size selectivity. When the soil aggregates were fragmented into 2–0.25 mm aggregate fractions, for silty loam and sandy clay loam, 0.002–0.02 mm and <0.002 mm particles were preferentially moved; for clay loam and loamy clay, >0.002 mm particles were preferentially moved. When the soil aggregates were fragmented into <0.25 mm aggregate fractions for soils with different textures, the 0.002–0.02 mm and <0.002 mm particles all exhibited preferential migration characteristics. This work provides an idea for improving the methods of aggregate stability measurements in the future. [ABSTRACT FROM AUTHOR]

The topography is a critical factor that determines the characteristics of regional soil formation. Small-scale topographic changes are defined as microtopographies. As a characteristic topographic condition in hilly mountainous regions, the redistribution of water and soil materials caused by microtopography is the main factor affecting the spatial heterogeneity of soil and the utilization of land resources. In this study, the influence of microtopography on pedogenesis was investigated using soil samples formed from mudstones with lacustrine facies deposition in the middle of the Sichuan Basin and developed into hill landforms by erosion of flowing water. Soil profiles were sampled along the slopes at the summit, shoulder, backslope, footslope, and toeslope positions. The morphological, physiochemical, and geochemical attributes of profiles were analysed. The results showed that the soil thickness increased significantly with changes in the soil profile configuration from the summit to the toeslope, and the profile configuration changed from A-C to A-B-C. The migration direction of Ca and Na at the summit, backslope, and footslope changed from enrichment to leaching, whereas that of Al, Fe, and Mg changed from leaching to enrichment. At the summit and shoulder of the hillslope, weathered materials are transported away by gravity and surface erosion, and new rocks are often exposed; therefore, the characteristics of soil development is relatively weak. However, in flat areas such as the footslope and toeslope with sufficient water conditions, the long-term contact between water, soil, and sediment leads to further chemical weathering, resulting in highly developed characteristics. Microtopography can affect physicochemical properties, chemical weathering, and redistribution of water and materials, resulting in differences in pedogenic characteristics at different slope positions. [ABSTRACT FROM AUTHOR]

Ridge tillage is one of the essential tillage methods in China. It affects the soil structure by altering the soil-water environment. With the rapid development of agricultural mechanization, the mechanized ridge tillage technology that combines modern mechanized agriculture with conservation tillage has become a pertinent agricultural production technology in the hilly regions. However, to date, the effects of mechanized ridge tillage on soil structure have garnered little attention. In this study, a field plot experiment involving the following four treatments: conventional tillage with rice and winter fallow (CK1), conventional tillage with rice-rape rotation (CK2), wide ridge tillage with rice-rape rotation (BT), and narrow ridge tillage with rice-rape rotation (RT) was conducted to study the effects of mechanized ridge tillage with rice-rape rotation on soil aggregate stability and soil porosity. The results indicated that mechanized ridge tillage could reduce the porosity of pores > 30 μm in diameter and increase the porosity of pores < 0.5 μm. Furthermore, mechanized ridge tillage could increase soil aggregate stability; the order of average mass diameter and geometric average diameter was RT > BT > CK2 > CK1. The BT and RT treatments could increase the agglomeration degree of the soil particles, which followed the order of RT > BT > CK2 > CK1. Therefore, mechanized ridge tillage with rice-rape rotation is effective in enhancing soil structure. [ABSTRACT FROM AUTHOR]

The orderly circulation of land can affect the structure of the agricultural industry, improve the level of agricultural industrialization, and realize the sustainable development of agriculture. Located in the inland of southwest China, Chongqing is the core area of China's Three Gorges Reservoir area, with obvious mountain characteristics. The characteristics and influencing factors of land transfer here can guide the reformation of land policy in other rural areas. Therefore, based on the survey data of 1015 mountain farmers in Chongqing, this paper employs a multi-class logistic model to analyze the above issues. The results show the following: (1) The phenomena of "zero rent" and "non-agreement" are widespread, and the spontaneous internal transfer among farmers is the main influencing factor. The decline in land value, the low degree of foreign investment, and the low average level of farmers' understanding of land transfer policies are quite different from the economically developed plains in the east. (2) Different directions of land circulation have different influencing factors. (3) The main factors are the total population of rural households, the proportion of non-agricultural household income, the age of the head of the household, the education level of the head of the household, the degree of land division, and the quality of land grades that affect land transfer and development in mountainous areas. Thus, improving the education level or technological training of farmers, establishing effective market mechanisms, and increasing income from non-agricultural employment can effectively promote land transfer. Moreover, age-oriented land policy is easier to implement. [ABSTRACT FROM AUTHOR]

The economic and social orientation of cultivated land in underdeveloped mountainous areas is obvious. A study of the spatial agglomeration characteristics of cultivated land quality can provide guidance for regional economic and social development. Taking Pengshui County, Chongqing, China as the study area, the spatial agglomeration characteristics of cultivated land quality indexes at county, township and village levels were analyzed by using the auto-correlation analysis method. The results showed that: (1) At different spatial scales, the cultivated land quality index showed spatial agglomeration characteristics. (2) Moran's I values of the cultivated land quality index at county, township and village level decreased successively, but three indexes still showed significant positive spatial correlation. (3) The spatial scale affects the spatial agglomeration of the cultivated land quality index, and its influence is physical, with a utilization and economic quality grade index from large to small. In underdeveloped mountainous areas, the spatial agglomeration characteristics of township scale and physical quality grade index are the most stable and significant, which can be used as the direct basis for zoning of cultivated land protection and site selection of rural residents' agglomeration points. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment is popular in reforming biomass for light-emitting carbon dots for multiple applications, but until now no work has been done on the hydrothermal treatment of soil organic matter (SOM) for this transformation. This work translates the knowledge from the chemical synthesis of carbon dots to the monitoring of SOM by a facile hydrothermal treatment of soils without the usage of toxic chromate chemicals: hydrothermally treated soils produce light-emitting carbon dots whose light absorbance and photoluminescence (PL) was attempted to correlate with the content of SOM. The light absorbance of the carbon dots was found to be correlated very well (R2 around 0.7) with the SOM by Walkley-Black acid digestion, but the PL was poor in describing the SOM. The absorbance at 250 nm related to the π-π* transition was less affected by pH or but can be reduced by high concentration ammonia. While the absorbance at wavelengths longer than 300 nm was variable, but it still can be used for SOM quantification. The fundamental optical properties are explored via PL and PL excitation spectroscopies to provide an overview of the monitoring of SOM using facile light-absorbance method. [ABSTRACT FROM AUTHOR]

The study of the pedogenic process in response to natural evolution, gradual anthropogenic shifts and engineering upheavals is of great significance for understanding, utilizing and transforming nature in the future. Although scholars have considered anthropic activities to be an important factor affecting pedogenesis, research on how and how much anthropic activities influence the soil-forming process is scant. This paper was conducted to analyse pedogenic characteristics dominated by anthropic activities. In this study, the parent materials and soils undergoing natural evolution (NE), tillage perturbation (TP) and engineering perturbation (EP) were selected as research objects. The genetic characteristics of soils undergoing NE, TP and EP are investigated mainly from three aspects: soil profile macromorphological characteristics, soil physical and chemical properties and chemical weathering characteristics. The results indicated that the influence of anthropic activities (TP and EP) on the process of pedogenesis is complicated. First, compared with NE, TP decreases the thickness of topsoil from 22.2 to 21.2 cm, while EP increases the thickness of topsoil from 22.2 to 23.2 cm, and EP causes the soil to have a high profile development index. Second, compared with TP, EP can improve bulk density (BD), soil organic carbon (SOC), total nitrogen (TN) and cation exchange capacity (CEC), Finally, the chemical weathering intensity differed among NE, TP and EP and followed the order of TP > NE > EP. Therefore, in the future, the genetic characteristics of soils dominated by anthropic activities should be considered. This will help us systematically understand the genesis and evolutionary characteristics of soil and lay a foundation for further perfecting the diagnostic horizon and diagnostic characteristics of the Soil Taxonomy and World Reference Base. [ABSTRACT FROM AUTHOR]

Sloping croplands could result in soil erosion, which leads to non-point source pollution of the aquatic system in the Three Gorges Reservoir Region. Mulberry, a commonly grown cash plant in the region, is traditionally planted in contour hedgerows as an effective management practice to control soil erosion and non-point source pollution. In this field study, surface runoff and soil N and P loss on sloping land under crop-mulberry management were investigated. The experiments consisted of six crop-mulberry treatments: Control (no mulberry hedgerow with mustard-corn rotation); T1 (two-row contour mulberry with mustard-corn rotation); T2 (three-row contour mulberry with mustard-corn rotation); T3 (border mulberry and one-row contour mulberry with mustard-corn rotation); T4 (border mulberry with mustard-corn rotation); T5 (two-row longitudinal mulberry with mustard). The results indicated that crop-mulberry systems could effectively reduce surface runoff and soil and nutrient loss from arable slope land. Surface runoff from T1 (342.13 m hm), T2 (260.6 m hm), T3 (113.13 m hm), T4 (114 m hm), and T5 (129 m hm) was reduced by 15.4, 35.6, 72.0, 71.8, and 68.1 %, respectively, while soil loss from T1 (0.21 t hm), T2 (0.13 t hm), T3 (0.08 t hm), T4 (0.11 t hm), and T5 (0.12 t hm) was reduced by 52.3, 70.5, 81.8, 75.0, and 72.7 %, respectively, as compared with the control. Crop-mulberry ecosystem would also elevate soil N by 22.3 % and soil P by 57.4 %, and soil nutrient status was contour-line dependent. [ABSTRACT FROM AUTHOR]

As a kind of human activity, the land consolidation deeply affects soil properties. The objective of this work was to analyze the impacts of land consolidation on soil physical and chemical properties such as soil depth, organic matter, aggregate stability and water retention capacity in 3 sample areas of purple region. Three different land consolidation histories were studied: One with 19 months (District I), one with 7 months (District II), and another within 1 month (District III). Samples of the soil surface were collected at the same points before and after the land consolidation using the GPS (Global Positioning System) positioning technique. Meanwhile, principal component analysis (PCA) and cluster analysis (CA) were applied to explore the changes of relationship between soil properties under the effects of the land consolidation. The results showed that changes of the soil properties were observed after the land consolidation in the 3 districts. In a scale of short time (19 months in this paper), the length of land consolidation history still affected the changes of soil characteristics. Soils collected in District I after consolidation were characterized by better soil properties, such as higher silt content and clay content (P<0.05), lower sand content (P<0.05), higher organic matter and cation exchange capacity (increased by 9.59% and 13.84%, respectively, P<0.05), and lower available water capacity (decreased by 33.22%, P<0.05). In District II after consolidation, soil depth increased to 25 cm (P<0.05), and gravel content and soil available water capacity significantly increased (P<0.05) as well. The land consolidation may bring about serious soil compaction, and this negative influence mainly occurred within very short time just after the consolidation, which could be testified by District I. In District I after consolidation, bulk density and the percentage of aggregate destruction were respectively 14.63% and 58% higher than those before consolidation (P<0.05), while silt content and organic matter were respectively 14.16% and 24.95% lower than those before consolidation (P<0.05). And the increased available water capacity (P<0.05) in District II and I were mainly due to the thickened soil depth. The variability of most soil properties in District I and I decreased after the land consolidation, which indicated that the spatial distribution of soil properties grew more uniform through the consolidation in these districts. Based on the PCA, some changes in the relationships between soil properties under the effects of the consolidation were observed. The change of cluster analysis classifications in District I was the smallest, but the degree of the correlation relationships between the variables decreased. Although the change of cluster analysis classifications in District II was great, the degree of the correlation relationships between the variables increased. Both before and after the land consolidation, principal components of District I had the highest variance explained during 3 study districts. And in this study, there was no regularity on these changes among different consolidation histories, which may be due to the short time scale. But the two different methods of the hierarchical cluster analysis (Ward Linkage method and Average Linkage method) did not give the exactly same classifications. The Ward Linkage method allowed a better correlation between variables in the same group, while the other method had a better consistency with the results based on the PCA. In regard to the comparison of the 2 methods applied to classify the variables, it was obvious that more extensive information could be accessible by using more than one method. The results can serve as a basis for the further studies on the development of farmland consolidation in purple region. [ABSTRACT FROM AUTHOR]

Agricultural non-point source pollution has gradually become a major pollution source of lake eutrophication and deterioration of water quality in recent years. The Three Gorges Reservoir Region is both an important sensitive eco-economy area and a typical poverty-stricken mountain area. However, its unique geographical location, its irrational agricultural structure and its increasing serious agricultural non-point source pollution problems challenge the environment in this region. Hence, it is a necessity to take controlling agricultural non-point source pollution from the source as one of the most effective approaches. In current research, agricultural non-point source pollution control excessively depends on engineering and technology. Anyhow, the roles of agricultural planting structure adjustment and agricultural cleaner production which can reduce non-point source pollution should not be ignored. Promoting the adjustment of planting structure, reducing the use of chemical fertilizers and pesticides, and adopting agricultural cleaner production technologies not only help improve the land production capacity and agricultural products quality, but also effectively reduce the agricultural non-point source pollution. By these important measures for energy saving and emission reduction can be realized in Three Gorges Reservoir Region. Based on the dual goals of the optimal agricultural economic benefits and non-point source pollution emission reduction, the linear programming model was used to optimize the planting structure and clean agricultural production in the Three Gorges Reservoir Region. The optimization results showed that the optimal paths to maximize the crop net income were as follows: The land area for grain production should cover 119.16×104 hm2 but cleaner production area of rice-wheat, corn, soybean and tuber crops needs 31.91×104, 18.69×104, 6.79×104 and 19.55×104 hm2; the land area for vegetables planting should be 33.25×104 hm2 and its cleaner production area was 18.26×104 hm2; the total land area for tobacco, fruits and tea planting should be 17.05×104 hm2 and the cleaner production area was 2.65×104, 10.28×104 and 0.95×104 hm2. In the premise of stable grain production, the conventionally grown grain, corn and soybean planting area can be gradually reduced. Otherwise, the planting areas of tobacco, vegetables, fruits and tea can be appropriately increased. In the process of crops production, according to the present ecological agriculture construction, the clean production can be vigorously promoted. The soil testing and formulated fertilization areas for food production in rice, wheat, oil crops, corn and soybean must be expanded. The organic vegetable planting can be increased positively. If the construction of the vegetable greenhouse is strengthened, the farmers' household farming pattern will be affected, regulated, or transferred. Therefore, the losses of nitrogen and phosphorus in agricultural non-point source runoff can be decreased. The local government should encourage farmers to develop the sustainable agriculture and make them realize that if the agriculture nonpoint pollution can be mitigated, the greatest social welfare will be got in the Three Gorges Reservoir Region, which are the bilateral-won benefits. By this means, both the non-point source pollution can be controlled and the sustainable development of agricultural economy can be realized. Therefore, the optimization of various crops is important to control agricultural non-point source pollution. Space layout has played a decisive role in the process of the entire agricultural land system optimization. The economic and environmental comparative advantage of agricultural land can be achieved. The goal of total emission control of agricultural non-point can be achieved by reasonable structure adjustment and regional distribution of planting industry. Further research will be required to achieve the targets of controlling the total pollution emission. [ABSTRACT FROM AUTHOR]

In order to guide the delimiting permanent basic farmland in the mountain and hill areas, this paper sets up a multiple-objective decision model by using Chongqing Dianjiang as an example. The model is supported by data analysis using ArcGIS 10.1 and other software based on the 2012 Second Land Survey data and Land Use Overall Planning data of 25 towns, basic farmland planning data, soil data, and investigation of county and country Land and Resource departments using spatial distribution products of more than 10°C accumulated temperature in the cloud platforms of Geography National Condition monitoring. The model is also supported by the AHP (Analytic Hierarchy Process), Entropy Coefficient Method, TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution), and constraint fact. First, the subjective weight of each index is given based on the AHP method by analyzing and erecting the judgment matrix. The objective weight is obtained by using the Entropy Coefficient Method by building the judgment matrix to a normalized process. The value of measurement and closeness of positive and negative ideal points is reflected through erecting Euclidean distance in the normalized matrix. The higher was the value of measurement and closeness, the higher was the priority of land. The call-out qualifications of farmland are confirmed by the constraint fact method in 4 investigations, which supplies the conditions of the Construction land or general farmland. The paper concludes that in the standardized normal outcome of the farmland decision index, the optimum conditions are farmland irrigation, rainfall, transportation, and rural residential radiation. For most soil quality indexes, the range of equal value, STD, and CV are [0.2, 0.6], [0.1, 0.3], and [13, 75]. Overall, the value of CV is below medium while existing comparable large areas have a high value or a low value. Variation in subjective and objective weights of these indexes, after normalization, causes the maximum weight to be farmland irrigation and farmland connectivity. The minimum weight is more than 10°C accumulated temperature, average rainfall in natural conditions, organic carbon in soil quality by analytic hierarchy process, transportation, rural residential radiation, and towns radiation in distance condition. The most important conditions for selecting permanent farmland are farmland irrigation > farmland connectivity > towns radiation > soil organic carbon. According to the value of measurement and closeness of positive and negative ideal points, the quality of farmland is generally close to each other, and the distance condition is at it's best and comparatively stable. Therefore, whole performance is better. Four grades are divided as key, proper, adjusting, and reserved, in which farmland is chosen as permanent basic farmlands using the natural breaks method to reclassify the closeness degree. There are special differences among different grades in statistics and spatial patterns. Local departments prefer to select superior farmlands, which are in the 'key' and 'proper' grades, in the selection under constraint conditions. In the ultimately delimited results, the proportion of proper and adjusting grades increases, while the proportion of key and reserved grades decreases. The rationality, standardization, and practicability of the model are verified by comparison among ultimately delimited results, high weight index in the model, and a basic farmland protecting area plan. The multiple-objective decision method is not only suitable for delimitation of permanent basic farmland in the mountain and hill areas in southwest China, but also ensures red line and economic growth, which supplies the theoretical basis and the decision reference for the study of complementary delimitation in the mountain and hill areas. [ABSTRACT FROM AUTHOR]

Smooth land transfer, more efficient integration of various resources, and increases of land value are the key of sustainable development of agricultural industry. Based on the land use map of transferred land parcels, rural economic statistics, and sample survey data from 239 households in Xiaoyuan village of Ciyun town and Huangzhuang village, Yangyan village of Yongxing town, Jiangjin district, Chongqing, China, we analyzed the changing features of resource integration and its efficiency from land of scattered small operation to concentrated large scale operation as affected by land transfer and consolidation in hilly areas. Then, economic, social, ecological, and development values of cultivated land before and after land transfer were also estimated by the value estimation methods including income method, market method, opportunity cost method and shadow engineering method. The results indicated that the continuous farm land area was enlarged, land patch shape tended to be more regular and land surface was more flat as a resulted of land transfer and land consolidation. Besides, the agricultural infrastructure system was significantly improved. The relative improvement of mean land patch size, mean land patch shape index and land surface relative elevation increased by 38.19%, 2.54% and 30.95%, respectively. On the other hand, the absolute improvement of rural road density and field irrigation ditch density were more than 50 m/hm² and 75 m/hm², respectively. Moreover, agricultural production costs were increased and the comprehensive resource use efficiency was greatly improved. The labor and material cost for agriculture production per hectare after land transfer were 1.58-24.84 times and 1.22-8.04 times more than before, but the labor, land as well as capital productivities were 21.46 - 45.74 times, 6.26-14.59 times and 1.09-3.71 times higher than those before land transfer. The total input-output ratio of agricultural production after land transfer was 1.1 times higher than before. Furthermore, the area of investment for developing agricultural industry changed from agriculture only to diversities. Self-raised funds from farmers before land transfer accounted for 100%, while the proportion of farmers' self-raised funds and government investment were respectively 24.53%-79.31% and 20.69%-75.47% after land transfer. In addition, funds by financial institutions invested in agricultural production accounted for 18% and 13.54% in the case study areas of Q1 and Q6. Last, both the economic output value and social guarantee value of cultivated land had a significant growth and increased by more than twice after land transfer, while the ecological service value of cultivated land all declined with the average loss rate of 34.83%. At the same time, cultivated land value structure became imbalance. The social guarantee value accounted for more than 45% before and after land transfer. The ecological service value and economic output value before land transfer were more or less equal at around 25% each, while the economic output value increased by two times and ecological service value sharply reduced to less than 10% after land transfer. Since the new idea that land consolidation goes ahead by integrating funds of various agricultural sectors to focus on land parcels planning and agricultural infrastructure construction under the agricultural industrial development policy, farmers' transfer of their cultivated land driven by the interests of the market or guided by the government was more favorable for land transfer in hilly areas. The effect of land transfer and land consolidation not only facilitated the transformation of farmer's contracted land to professional investors, leading enterprises and family farms, but also led to the conversion of agricultural business models and agricultural industry types. Thus, it promoted the integration of various resources efficiently (e.g., land resource, agricultural infrastructure resource, capital, labor, etc.) and improved the resources integration efficiency, resulting in a significant increase in land composite value. These findings in our study contributed to a better understanding of the effect of the land transfer and consolidation on development of agricultural industry, and also provided a reference for the overall adjustment of regional land-use planning policy and agricultural development policies. [ABSTRACT FROM AUTHOR]

Major element compositions and chemical weathering features of the purple soils and their corresponding rocks in the Red Sichuan Basin, China were studied in this paper to infer the diagenetic features of the purple rocks and the pedogenetic features of the purple soils. The results showed that all of the rock and soil samples, except those from Yibin, have strongly similar major element compositions and the distribution patterns of their major element compositions are similar to those of the upper continental crust. Chemical index of alteration, chemical index of weathering and NaO/KO indicate that the purple soils and rocks have similar chemical weathering intensities, whereas the AlO-CaO* + NaO-KO (A-CN-K) relationship, suggests that chemical weathering was strong during diagenesis of the purple rocks, but weak during pedogenesis of the purple soils. Variations in major element compositions of the purplish rock samples, except that from Yibin, do not primarily reflect differences in compositions of the sediment source, sediment recycling and potassium metasomatism, and therefore the effects of chemical weathering on the major element compositions were mainly dependent on climate condition and the residence time of material exposed to chemical weathering. Chemical weathering of the purple rocks reached only moderate degrees under the general influence of warm and humid climate during Jurassic and Cretaceous. Warmer and more humid climate conditions partly resulted in stronger chemical weathering of rocks in the southern region of the basin than in the central and western region, whereas shorter residence time of material in upslope position partly resulted in weaker chemical weathering of rocks in the eastern region than in the central and western region. The same climate and stable tectonic setting led to comparable chemical weathering intensities of rocks in the Ziliujing and Jiaguan Formations. Gradually colder and dryer climate from Early Jurassic to Middle Jurassic then to Late Jurassic and shorter residence time in tectonically active setting of Middle Jurassic and late Late Jurassic resulted in the following order of chemical weathering intensity of the purple Jurassic rocks: Ziliujing Formation ≫ Shaximiao Formation ≈ Suining Formation > Penglaizhen Formation. [ABSTRACT FROM AUTHOR]

Traditional water allocation at a regional or basin scale can be too coarse to be used in a local area such as a village. For example, in the hilly area of Sichuan Basin the landform is fragmented and land use pattern consists of small farms. Furthermore, seasonal drought occurs frequently due to spatially and temporally variability in rainfall patterns. These droughts often lead to a reduction in crop yield or no yield at all. Due to the remoteness and scale of the farms, the farm populations are dependent on the annual crop yield. A poor harvest can mean serious hardships to the farmers. In order to mitigate the seasonal drought we first analyzed the drought characteristics from both meteorological and soil aspects. The results showed that both the spring droughts and canicular days (dog-day) droughts had in excess of a 60% chance of occurring. Using a water balance approach, we found that a series of storage ponds and bunds could greatly reduce the impact of these droughts. [ABSTRACT FROM AUTHOR]

An investigation was conducted to identify the characteristics of heavy metals in orange ecosystem in three areas in the Three Gorge Reservoir Region by using the modified Tessier sequential extraction procedure. The contents of Cu and Pb in different speciation fractions of the soils can be ordered as the Residual (F6)>Reducible (F4)>Oxidable (F5)>Water soluble (F1)>Carbonate (F3)>Exchangeable (F2), and the contents of Zn and Ni follow the order of the Residual (F6)>Oxidable (F5)>Reducible (F4)>Water soluble (F1)>Carbonate (F3)> Exchangeable (F2), and those of Cd follow the order of the Reducible (F4)>Oxidable (F5)>Exchangeable (F2)>Carbonate (F3)>Residual (F6)>Water soluble (F1). The concentrations of Cu in the different organs of oranges follow the increasing sequence of pulp>leaf>pericarp, those of Zn and Ni following the increasing sequence of leaf>pulp>pericarp, and those of Pb and Cd follow the increasing sequence of leaf>pericarp>pulp. Correlation degrees of different forms of same heavy metals in soils are according to the order of Cu>Zn>Cd>Pb>Ni. Correlation degrees of different heavy metals in same forms are according to the order that the forms of Reducible (F4), Oxidable (F5) and Residual (F6) are higher than the forms of Water soluble (F1), Exchangeable (F2) and Carbonate (F3). There are either positive or negative correlations between heavy metals in leaves and in pulp, while there are all positive correlations between heavy mentals in leaves and in pericarp. There are significant correlations between the concentrations of some heavy metals in leaves, pericarp or pulp, and those in speciation fractions in the soils. [ABSTRACT FROM AUTHOR]

A research trial with four land management practices, i.e., traditional tillage-fallow (TTF), traditional tillage-wheat (TTW), conservation tillage-fallow (CTF) and conservation tillage-wheat (CTW), was sampled in the 15th year after its establishment to assess the effects of different management practices on labile organic carbon fractions (LOCFs), such as easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC) and microbial biomass carbon (MBC) in a typical paddy soil, Chongqing, Southwest China. The results indicated that LOCFs were significantly influenced by the combination of no-tillage, ridge culture and crop rotation. And, different combination patterns showed different effectiveness on soil LOCFs. The effects of no-tillage, ridge culture and wheat cultivation on EOC, DOC, POC and MBC mainly happened at 0–10cm. At this depth, soil under CTW had higher EOC, DOC, POC and MBC contents, compared to TTF, TTW and CTF, respectively. Moreover, the contents of LOCFs for different practices generally decreased when the soil depth increased. Our findings suggest that the paddy soil in Southwest China could be managed to concentrate greater quantities of EOC, DOC, POC and MBC. [ABSTRACT FROM AUTHOR]

The conflicts among food security, economic development and ecological protection are the “sticking point” of undeveloped southwestern mountainous areas of China. The objectives of this study are to identify appropriate integrated indicators influencing the classification and gradation of cultivated land quality in the southwestern mountainous area of China based on semi-structure interview, and to promote the monitoring of cultivated land quality in this region. Taking Bishan County of Chongqing as a study case, the integrated indicators involved the productivity, protection, acceptability, and stability of cultivated land. The integrated indicators accord with the characteristics of land resources and human preference in southwestern mountainous area of China. In different agricultural zones, we emphasize different indicators, such as emphasizing productivity, stabilization and acceptability in low hilly and plain agricultural integrative zone (LHP-AIZ), protection, productivity and stability in low mountain and hill agro-forestry ecological zone (LMH-AEZ), and acceptability in plain outskirts integrative agricultural zone (PO-IAZ), respectively. The pronounced difference of classification and gradation of cultivated land, regardless of inter-region or intra-region, is observed, with the reducible rank from PO-IAZ, LHP-AIZ to LMH-AEZ. Research results accord with the characteristics of assets management and intensive utilization of cultivated land resources in the southwestern mountainous area of China. Semi-structure interview adequately presents the principal agent of farmers in agricultural land use and rural land market. This method is very effective and feasible to obtain data of the quality of cultivated land in the southwestern mountainous area of China. [ABSTRACT FROM AUTHOR]

The gradation of cultivated land is to assess the suitability of cultivated land for agricultural production in terms of natural and economic properties of land. It can be used to evaluate sustainability of land use and soil management practices. Formal and informal surveys, Delphi and comprehensive index method are adopted to identify appropriate integrated indicators, and measure the gradation of cultivated land quality. The determination of integrated indicators presents three basic features of cultivated land quality: stable plant productivity, social acceptability and maintenance of environmental quality. Pronounced concentration-dissipation law of total function score value occurs in paddy field units, with three ranges, i.e., 79∼68.5, 68.5∼59 and 59∼51. Total function score value in dryland units mainly ranges from 40 to 70, but slight concentration-dissipation law of each unit is still observed, with four ranges, i.e., 79∼68, 68∼51, 51∼37 and 37∼15. Paddy field quality is divided into three gradations, and the scales are 18 220.9 ha, 5410.6 ha and 2890.9 ha. Dryland quality is classified into four gradations, and the scales are 1548.6 ha, 8153.8 ha, 3316.3 ha and 685.2 ha. The total function score value of every gradation unit is conformed to the results of farmers’ assessment. Research results meet with the needs of accurate degree of the gradation of cultivated land quality. Integrated indicators-based gradation of cultivated land assessment accords with the characteristics of land resources and human preference in the mountains of southwestern China. This study will be useful to promote the monitoring of cultivated land quality, and to supply fine ground and knowledge for establishing appropriate cultivated land management practices in Southwestern China. [ABSTRACT FROM AUTHOR]

The 26 plots including natural forestland, secondary forestland, shrub-grassland, sloping cropland, artificial forest and abandoned field, were selected to discuss the impact of land cover on the soil characteristics in the three karst districts of Chongqing. The results showed that: (1) After the vegetation turned into secondary vegetation or artificial vegetation, or reclamation, soil physical properties would be degraded. In the surface-layer soil of sloping cropland, the contents of > 2 mm water-stable aggregates decreased obviously with apparent sandification. (2) The contents of soil organic matter and total nitrogen are controlled completely by vegetation type and land use intensity. The increasing trend is rather slow in the early days when over-reclamation is stopped and the land is converted to forest and pasture. (3) Herbaceous species increase and woody plants species decrease with the increase of land use intensity, therefore, the soil seed banks degrade more seriously. (4) The soil degradation index has been set up to describe the relative soil degradation degree under the conditions of different vegetation types. (5) Land cover has a significant effect on karst soil characteristics, land degradation in the karst ecosystem is essentially characterized by the different degradation of soil functions that serve as water banks, nutrient banks and soil seed banks. [ABSTRACT FROM AUTHOR]

Open space of metropolitan suburbs in mountain region, has been increasingly becoming the coupling mosaic structure of industrial actions and landscape behaviors. However, the local governments, when making land use planning, often aim at economic development, and rarely refer to the coordination of compatibilities and conflicts between industrial actions and landscape behaviors in the mosaic structure. In this study land use in the Jinyun Mountain and its surrounding area, Chongqing is adjusted by gray multi-objective programming approach and local-level decision-making process to cope with conflicts between objectives for human welfare and objectives for landscape conservation. The results indicate that: 1) the compatibilities and conflicts among different behavior characters and different landscape types result in the compatibilities of landscape to human behavior; 2) a land use planning in the study area is produced based on the sustainable land use and social-eco development, which pays more attention to the resources and environment constraints and economic objectives, and follows the distribution law of rare resources; 3) in the study area, cultivated land of 1,207.27 ha can meet the demands for food and byproducts by the residents there, orchard land and forestland of 632.55 ha, 2,276.61 ha, respectively can provide enough space for the local people to improve their living structure and meet their demands for recreational activities, and urban residential land, rural residential land, mining land and transportation land of 1,107.60 ha, 120.27 ha, 162.48 ha, 100.91 ha, respectively can satisfy the resident’s economic development and infrastructures; 4) the equilibrium among industrial actions, landscape accessibility and ecological conservation can be obtained by analyzing the possible impacts of human activities on landscape ecological process in open space of metropolitan suburbs in mountain areas. [ABSTRACT FROM AUTHOR]

In order to evaluate the soil erosion rate for different land uses and make recommendations on land-use alternatives for erosion control in hilly and mountain areas on a Purplish soil (Regosols in FAO taxonomy), experimental data were obtained from three continuously monitored sites located at Yanting, Nanbu and Pengxi of Sichuan province. The data showed that the rank of erosion rate is farmland > unfenced grassland > fenced grassland > forestland. The erosion rate of farmland was more than 3 times higher than that of forestland and fenced grassland, indicating that restricting human activity is crucial for over-erosion. The erodibility was higher at the initial period of rainy season for all the three types of land use. The erosion rates of fenced grassland and mature afforestation land were not proportional to rainfall intensity because these land uses changed impact energy of the rainfall. This research showed that restricting human activity, intensifying the management of initial period of rainy season, and increasing the cover rate of land surface are the three major measures for soil erosion prevention. It is recommended that farmers should cease cultivation on farmland at the top of hills and steep slope land return those lands back to grassland or forestland. [ABSTRACT FROM AUTHOR]

Abstract Permanently flooded rice fields, widely distributed in south and south-west China, emit more CH4 than those drained in the winter crop season. For understanding CH4 emissions from permanently flooded rice fields and developing mitigation options, CH4 emission was measured year-round for 6 years from 1995 to 2000, in a permanently flooded rice field in Chongqing, China, where two cultivations with four treatments were prepared as follows: plain-cultivation, summer rice crop and winter fallow with floodwater layer annually (convention, Ch-FF), and winter upland crop under drained conditions (Ch-Wheat); ridge-cultivation without tillage, summer rice and winter fallow with floodwater layer annually (Ch-FFR), and winter upland crop under drained conditions (Ch-RW), respectively. On a 6-year average, compared to the treatments with floodwater in the winter crop season, the CH4 flux during rice-growing period from the treatments draining floodwater and planting winter crop was reduced by 42% in plain-cultivation and by 13% in ridge-cultivation (P < 0.05), respectively. The reduction of annual CH4 emission reached 68 and 48%, respectively. Compared to plain-cultivation (Ch-FF), ridge-cultivation (Ch-FFR) reduced annual CH4 emission by 33%, and which was mainly occurred in the winter crop season. These results indicate that draining floodwater layer for winter upland crop growth was not only able to prevent CH4 emission from permanently flooded paddy soils directly in the winter crop season, but also to reduce CH4 emission substantially during the following rice-growing period. As an alternative to the completely drainage of floodwater layer in the winter crop season, ridge-cultivation could also significantly mitigate CH4 emissions from permanently flooded rice fields. [ABSTRACT FROM AUTHOR]

The rural settlements in poverty-stricken mountainous areas are the "living fossils" of an economic society with the characteristics of spatial dispersion and are slowly changing. Spatial agglomeration is the development direction of rural settlements. In-depth exploration of the spatial agglomeration characteristics and influencing factors of rural settlements in poverty-stricken mountainous areas is a way to provide a basis for rural settlement restructuring. We selected Pengshui County, a national poverty-stricken county in the southwestern mountainous area of China, as the research area. Spatial buffer and kernel density analysis were used to analyze the agglomeration characteristics of rural settlements and influencing factors. The results show that: (1) The rural settlements are small in scale and the space is evenly dispersed. 55.63% of the rural settlements' sizes are less than 1000 m2, 84.15% of the rural settlements' sizes are less than 2500 m2, and 92.81% of the rural settlements are within 200 m. (2) The elevation and slope of topographic factors have a significant agglomeration effect on rural settlements. However, the slope direction has no agglomeration effect. 85.41% of rural settlements (52.75% of rural settlements are gathered between 400 and 800 m above sea level) are gathered at an altitude of 1000 m or less, and 77.59% of rural settlements are gathered with a slope of 6~25°. Additionally, there are few rural settlements with a slope of 0~2°. Moreover, the distribution of residential areas has no agglomeration effect on rural settlements. (3) The cultivated land exerts the most significant effect on rural settlements followed by roads and water sources, while the role of urban land is weak. 99.48% of rural settlements are concentrated in the 100 m area of cultivated land. Therefore, in the poverty-stricken mountainous areas in the southwestern mountainous areas of China, convenient farming is the primary condition for production and living. Rural settlements are highly correlated with cultivated land. Rural settlements are scattered and concentrated with the scattered cultivated land. The rural settlements were leaded by the distribution of cultivated land. Less high-quality cultivated land with less slope were occupied or not by rural residential areas' people. [ABSTRACT FROM AUTHOR]

Classified as Regosols in the Food and Agriculture Organization (FAO) Taxonomy, purple soils formed from purple rocks and are mainly distributed in the Sichuan Basin of southwestern China. A number of studies have focused on the soil water, nutrients, texture and erosion of purple soils. This study was conducted to understand the lithological features of the related purple rocks and their effects on the pedogenesis of purple soils in the Sichuan Basin. The results showed the following: due to variability in the paleoenvironment, purple rocks mainly consist of sandstone and mudstone with various stratal thicknesses and various particle sizes. The lithology of the purple rocks leads the purple soils have an obvious inheritance from their parent rocks. An apparent purple color and numerous rock fragments derived from the purple parent rock are observed throughout the profile, with no clear soil stratification. The particle size contents of the purple soils are closely related to those of their parent rocks. The clay-sized fractions in the purple soils are generally dominated by illite, vermiculite, chlorite, and montmorillonite with little quartz and with or without kaolinite, which is generally the same as that in the parent purple rocks. In addition, the purple soils are characterized by obvious inherited mineralogy, chemical composition, pH value, OM content and nutrient content. Therefore, the diagenetic environment determined the lithology of the purple rock, and the lithology of the purple rock determined the pedogenic characteristics of the purple soil to some extent. Purple soils are characterized by rapid physical weathering and pedogenetic processes and slow chemical pedogenetic processes. [ABSTRACT FROM AUTHOR]

Farming plot construction engineering in hilly areas plays an important role in the mechanization, large-scale production and industrialization of agriculture. The method is undertaken to improve water and soil conservation, enhance soil fertility and extend machinery agriculture. However, the positive effects of engineering require years to mature. The properties of newly reconstructed soil are not sufficient, i.e., with poor structure and low water holding capacity, resulting in deterioration of its physical properties and erosion. To date, most studies on plot characteristics and soil properties in farming plot construction engineering have neglected the influence of soil erosion. This paper addresses soil erosion characteristics at sites to define the appropriate slope length for newly reconstructed gentle-slope lands. Six field plots with a 10° slope gradient and different lengths (5, 10, 20, 30, 40, and 50 m) were established under natural rainfall and simulated overland flow conditions. The soil detachment rate, runoff shear stress and stream power exhibited the same trends as runoff and soil loss. The soil erosion characteristics varied at sites with different slope lengths, and the degree of soil erosion reached its minimum on gentle-slope land sites of 30 or 40 m. Therefore, 30-40 m slope lengths may be the recommended range to control soil loss from newly reconstructed gentle-slope lands. The conclusions of this study provide theoretical guidance for farming plot construction engineering, which can promote the sustainable development of cultivated land resources in hilly mountainous regions. [ABSTRACT FROM AUTHOR]