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Phosphorus Loss from Dry Sloping Lands of Three Gorges Reservoir Area, China

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Pedosphere 2013年第3期23卷 385-394页

作者： HU Zheng-Feng GAO Ming xie de-ti WANG Zi-Fang College of Resources & Environment Southwest University Chongqing Municipal Environmental Protection Bureau

Eutrophication in the Three Gorges Reservoir has become a serious issue, and phosphorus (P) is the nutrient thought to be primarily responsible although there are few studies about P loss from the mostly sloping farmlands of the area. This work investigated the amounts and forms of P loss from 9 farmlands with the slopes of 4°, 9°, and 17° in a small watershed, Wangjiagou in Fuling District, Chongqing of China. The slope of the relationship between runoff and rainfall increased with field slope; i.e., there was a significant interaction between the effects of rainfall and field slope on water export. For sediment export by surface runoff, there was no interaction between field slope and rainfall, and the intercept of the relationship between rainfall and sediment loss was significantly different for the 3 slopes. The main P loss was from sediments, regardless of slope. In the runoff water, particulate P was the largest P fraction, and its loss was greatest from the steepest land and least from the flattest. The release of total P and available P from sediments followed the same trend. The P loss during May to July in Wangjiagou was more than 60% of the annual total.

关键词： agricultural production area erosion nutrient loss purple soil soil loss

Effects of Land Management Practices on Soil Water in Southwestern Mountainous Area, China

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Agricultural Sciences in China 2008年第7期7卷 871-886页

作者： SHAO Jing-an WEI Chao-fu xie de-ti College of Resources and Environment Southwest University Chongqing 400716 P.R. China Geography Science Institute of Chongqing Normal University Chongqing 400047 P.R. China

The effects of selected land management practices （cross-sloping tillage, ridge culture, organic manure, and straw mulch） on soil water conservation in a southwestern mountainous area, China, were studied during November 2002 to November 2004. The experimental field is divided into three parts based on soil layer depths, 0-60 cm （part Ⅰ）, 0-40 cm （part Ⅱ）, and 0- 20 cm （part Ⅲ）, and they all had the same slope azimuth （SE）, slope （10°）, and slope type （linear）. The experimental plots were subjected to the following treatments： cross-sloping tillage （CST）; cross-sloping tillage with organic manure （CST/ OM）; cross-sloping tillage with straw mulch （CST/SM）; contour ridge culture （CRC）; contour ridge culture with organic manure （CRC/OM）; and contour ridge culture with straw mulch （CRC/SM）, to identify the effects of management practices on soil water. Water contents were determined for soil samples collected, using a 2.2 cm diameter manual probe. Soil water was monitored once every five days from Nov. 20, 2002 to Nov. 20, 2004. The results indicated that, in the study stages, an integration of rainfall, evaporative losses, and crop transcription controlled the basic tendencies of profile （mean） soil water, while land management practices, to a certain extent, only modified its amount, distribution, and routing. Moreover, these modifications also mainly focused on the first 20 cm depth of topsoil layer. When each management practice was compared with control treatment, season changes of profile （mean） soil water were pronounced, while interannual changes among them were not significant. More comparisons indicated that, in the study stages, contour ridge culture had better effects than cross-sloping tillage. And under the same tillage, the combination of organic manure could achieve more than straw mulch. These management practices should be recommended considering the effectiveness of soil and water management techniques in the southwestern mountainous area, China.

关键词： land management practices soil water precision water management southwestern mountainous area China

Effect of four crop straws on transformation of organic matter during sewage sludge composting

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Journal of Integrative Agriculture 2016年第1期15卷 232-240页

作者： ZHAO Xiu-lan LI Bi-qiong NI Jiu-pai xie de-ti College of Resources and Environment Southwest University/Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Educatior Chongqing 400716 P.R.China Key Laboratory of Agricultural Resources and Environment of Chongqing Chongqing 400716 P.R.China

A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances （HS）, fulvic-like acids （FA） and humic-like acids （HA） were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.

关键词： sewage sludge crop straw composting organic matter degradation humification

Assessing the Real Value of Farmland in China

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Journal of Mountain Science 2014年第5期11卷 1218-1230页

作者： HU Rong QIU Dao-chi xie de-ti WANG Xin-ya ZHANG Lin School of Resources and Environment Southwest University School of Geographical Science Southwest University Bureau of land resource management in Yuzhong district

The preservation of farmland is a growing concern in China because the fact that China possesses limited land resources and the world's largest population presents a clear contradiction. Only when the value of farmland is fully appreciated in commercial markets can farmland preservation be effectively achieved. The current study constructed a model to evaluate the economic, social, and ecological value of farmland in China according to the connotation of values. As a case study, the value of Chinese farmland was estimated in 1999, 2002, 2005, 2008, and 2011 using the established model. Although the amount of farmland was greatly reduced from 1999 to 2011 due to constructive occupation, agricultural restructuring, ecological restoration, and disaster destruction, the value of this farmland increased from 220.71×1012 to 736.26×1012 RMB Yuan as a result of the multifunctional nature and scarcity of farmland during the same period. The potential value of farmland in China was huge, but the value in the market was greatly underestimated, especially in regard to its social and ecological value. This study proposes a new method that integrates the discounted value of all future services provided by a natural resource(for the society and individuals) to evaluate the resource assets, provides a scientific foundation for the preservation and operation of farmland assets, and explores ways to increase farmers' property income.

关键词： Farmland resource Farmland preservation Real value Land China

LAND USE CHANGE AND ITS SOCIO-ECONOMIC DRIVING FORCES UNdeR STRESS OF PROJECT IN OLD RESERVOIR AREA——Case Study of Linshui Reservoir Area of Dahonghe Reservoir in Sichuan Province

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Chinese Geographical Science 2005年第4期15卷 315-324页

作者： SHAO Jing-an HUANG Xue-qin QU Ming WEI Chao-fu xie de-ti College of Resource and Environment Southwest University Chongqing 400716 P. R. China Chongqing Key Laboratory of Digital Agriculture Chongqing 400716 P. R. China

The old reservoir areas built in 1950s- 1970s left behind many socio-economic problems, because of the administrative backward migration and little migration fund, and all these problems would be tied to land. Based on interviewing with peasant households, combining land use survey and socio-economic statistical index, this paper analyzed land use change and its corresponding driving forces in Linshui reservoir area of Dahonghe Reservoir. Results showed that land use change in the reservoir area was mainly embodied on low-lying land submergence and migration requisition land. The former changed the land use patterns, and the latter mainly reconstructed original land property and made land over-fragmented. Cultivated land per capita was 0.041ha in this area, below the cordon of cultivated land per capita enacted by FAO. Currently, there were still 30.25% of peasant households being short of grain in trimester of one year, and there were 35.27% of people living under the poverty line. The conditions of eco-environmerit in Linshui Reservoir Area were worse, and healthy and sub-healthy eco-environment accounted for less proportion, composed of green belt around the reservoir area and paddy field ecosystem, and economic forest and orchard ecosystem, respectively. The stress of the reservoir project was macroscopic background to analyze the driving factors of land use change, and real underlying diving factor of the land use change in the area was the change of cultural landscape under the stress of reservoir project. The rapid increase of population was the key factor to induce the change of man-land relationship in the reservoir area, the low level of rural economy was the crucial factor to decide how migrants input for production, and the belief of migrants, influencing the land use patterns in a certain extent, was the inducing factor to keep land use stable. The low-lying submergence and infrastructure construction accompanied the reservoir project were leading facto

关键词： land use change socio-economic driving factor project stress old reservoir area

Assessing effects of “source-sink” landscape on non-point source pollution based on cell units of a small agricultural catchment

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Journal of Mountain Science 2019年第9期16卷 2048-2062页

作者： WANG Jin-liang CHEN Cheng-long NI Jiu-pai xie de-ti GUO Xi LUO Zhi-jun ZHAO Yue School of Land Resources and Environment Jiangxi Agriculture University Nanchang 330045 China School of Resources and Environment Southwest University Chongqing 400715 China Research Center for development and Utility of Unique Resources in the Wulingshan Region Yangtze Normal Universityf Fuling 408100 China

Ascertaining the relationship between "source-sink" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To reveal the relationships between "sourcesink" landscape and NPS pollution based on cell units of a small catchment in the Three Gorges Reservoir Region(TGRR), the runoff and nutrient yields were simulated first by rainfall events on a cell unit scale based on the Annualized AGricultural Non-Point Source Pollution Model(AnnAGNPS). Landscape structure and pattern were quantified with "sourcesink" landscape indicators based on cell units including landscape area indices and locationweighted landscape indices. The results showed that:the study case of small Wangjiagou catchment highlighted a good prediction capability of runoff and nutrient export by the AnnAGNPS model. Throughout the catchment, the spatial distribution trends of four location-weighted landscape indices were similar to the trends of simulated total nitrogen(TN) and total phosphorus(TP), which highlighted the importance of spatial arrangement of "source" and "sink" landscape types in a catchment when estimating pollutant loads. Results by Pearson correlation analysis indicated that the location-weighted landscape index provided a more comprehensive account of multiple factors, and can better reflect NPS-related nutrient loss than other landscape indices applied in single-factor analysis. This study provides new findings for applying the "source-sink" landscape indices based on cell units in small catchments to explain the effect of "source-sink" landscape on nutrient export based on cell unit, and helps improve the understanding of the correlation between "source-sink" landscape and NPS pollution.

关键词： Nutrient load Non-point source pollution Source sink Landscape index Small catchment

Source-sink landscape spatial characteristics and effect on non-point source pollution in a small catchment of the Three Gorge Reservoir Region

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Journal of Mountain Science 2018年第2期15卷 327-339页

作者： WANG Jin-liang NI Jiu-pai CHEN Cheng-long xie de-ti SHAO Jing-an CHEN Fang-xin LEI Ping School of Resources and Environment Southwest University School of Geography and Tourism Chongqing Normal University

The source and sink landscape patterns refer to landscape types or units that can either promote positive evolvement of non-point source(NPS) pollution process, or can prevent/defer the ecological process, respectively. Therefore, the role of a catchment landscape pattern in nutrient losses can be identified based on the spatial arrangement of source and sink landscapes. To reveal the relations between landscape spatial characteristics and NPS pollution in small catchment, a case study was carried out in a Wangjiagou small catchment of the Three Gorges Reservoir Region(TGRR), China. Google earth imagery for 2015 were processed and used to differentiate source and sink landscape types, and six subcatchments were selected as sample regions for monitoring nitrogen and phosphorus *** elevation, slope gradient and relative flow length was used to construct the Lorenz curves of different source and sink landscape types in the catchment, in order to assess the source and sink landscape spatial characteristics. By calculating the location-weighted landscape indices of each subcatchment and total catchment, the landscape spatial load characteristics affecting the NPS pollution was identified, with a further Pearson correlation analysis for location-weighted landscape indices and nitrogen-phosphorus monitoring indicators. The analysis of Lorenz curve has revealed that the obtained distribution trend of Lorenz curve and curve area quantified well the spatial characteristics of source and sink landscape pattern related to the relative elevation, slope gradient and relative flow length in small catchment. Results of Pearson correction analysis indicated that location-weighted landscape index(LWLI) combining of terrain and landscape type factor did better in reflecting the status of nitrogen and phosphorus loss than the indices related to relative elevation, slope gradient and relative flow length.

关键词： Source-sink landscape Non-point sourcepollution Nutrient loss Lorenz curve Landscapeindex Small catchment

Combining Ridge with No-tillage in Lowland Rice-Based Cropping System: Long-Term Effect on Soil and Rice Yield

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Pedosphere 2009年第4期19卷 515-522页

作者： JIANG Xian-Jun2 and xie de-ti College of Resources and Environment, Southwest University, 216 tiansheng Road, Beibei, Chongqing 400716 (China) College of Resources and Environment Southwest University 216 Tiansheng Road Beibei Chongqing 400716 (China)

A tillage method of combining ridge with no-tillage (RNT) was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern, soil water stable aggregate distribution, nutrients stratification and yields of rice and post-rice crops. After flooded paddy field (FPF) was practiced with RNT for a long time, soil profile changed from G to A-P-G, and horizon G was shifted to a deeper position in the profile. Also the proportion of macroaggregate (> 2 mm) increased, whereas the proportion of silt and clay (decreased under RNT, indicating a better soil structure that will prevent erosion. RNT helped to control leaching and significantly improved total N, P, K and organic matter in soil. The highest crop yields were found under RNT system every year, and total crop yields were higher under conventional paddy-upland rotation tillage (CR) than under FPF, except in 2003 and 2006 when serious drought occurred. RNT was proven to be a better tillage method for lowland rice-based cropping system.

关键词： aggregate-size distribution conservative tillage flooded paddy field soil profile pattern

tillage Effect on Organic Carbon in a Purple Paddy Soil

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Pedosphere 2006年第5期16卷 660-667页

作者： HUANG Xue-Xia GAO Ming WEI Chao-Fu xie de-ti PAN Gen-Xing College of Resources and Environment Southwest Agricultural University Chongqing 400716 （China） College of Environmental Science and Technology Guangzhou University Guangzhou 510006 （China） College of Resources and Environment Nanjing Agricultural University Nanjing 210095 （China）

The distribution and storage of soil organic carbon (SOC) based on a long-term experiment with various tillage systems were studied in a paddy soil derived from purple soil in Chongqing, China. Organic carbon storage in the 0-20 and 0-40 cm soil layers under different tillage systems were in an order: ridge tillage with rice-rape rotation (RT-rr) > conventional tillage with rice only (CT-r) > ridge tillage with rice only (RT-r) > conventional tillage with rice-rape rotation (CT-rr). The RT-rr system had significantly higher levels of soil organic carbon in the 0-40 cm topsoil, while the proportion of the total remaining organic carbon in the total soil organic carbon in the 0-10 cm layer was greatest in the RT-rr system. This was the reason why the RT-rr system enhanced soil organic carbon storage. These showed that tillage system type was crucial for carbon storage. Carbon levels in soil humus and crop-yield results showed that the RT-rr system enhanced soil fertility and crop productivity. Adoption of this tillage system would be beneficial both for environmental protection and economic development.

关键词： carbon sequestration organic carbon storage purple paddy soil tillage system