Table of Content

Volume 38 Issue 11
25 November 2022
Study on Spatial-temporal Evolution and Driving Factors of Ecosystem Service Value in the Yangtze River Delta Urban Agglomerations
MA Wei-bo, YANG Fan, WANG Nan, ZHAO Li-jun, TAN Kun, ZHANG Xiao-fei, ZHANG Long-jiang, LI Hai-dong
2022, 38(11):  1365-1376.  doi:10.19741/j.issn.1673-4831.2022.0403
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Urban ecological well-being is increasingly concerned these years. Exploring the driving effect of ecosystem service value (ESV) of urban agglomerations has essential reference significance for improving urban ecological well-being and human settlement health. Taking 27 cities in the Yangtze River Delta Urban Agglomeration (YRDUA) as the research object, the driving characteristics and driving path evolution characteristics of 10 indicators of human activities and natural conditions on ESV were explored by using random forest (RF) and structural equation model (SEM). The results show that: (1)During 2000-2020, the overall ESV of the YRDUA decreased first and then increased. Its spatial distribution pattern show that: the highest in key lakes, wetlands, and water systems, followed by hills in the south, farmland in the north, and the lowest in the built-up area of the urban agglomeration. (2) There is a strong spatial aggregation mode of ESV in the YRDUA. For example, during 2000-2020, the hot spot effect of ESV had risen remarkably in the contiguous areas of Yangzhou-Taizhou-Yancheng, Changzhou-Wuxi-Suzhou-Huzhou and Ma'anshan-Nanjing, and in the coastal wetland of Yancheng-Nantoug was very remarkable. (3) The driving influence of water area in the YRDUA on ESV is greater than other factors. SEM shows that the driving factors explain the changes of the ESV in 2000, 2010, 2020, and 2000-2020 through direct and indirect means in different degrees of 85%, 84%, 83%, and 72%, respectively. It is found that the changing process of cold and hot spots of ESV spatial aggregation in the YRDUA reflects the evolution characteristics of urbanization in this area from the side, the water area drives ESV in a very significant and direct way. In addition to the direct way, forest land area drives ESV through an importantly indirect path. It is suggested to consider the direct and indirect driving effects of all factors comprehensively and improve the ESV of urban ecosystem from the perspective of integrated development of urban agglomerations.
Spatial-temporal Evolution of Habitat Quality and Its Influencing Factors in Ecological Conservation Area in Sichuan-Yunnan Provinces Based on Value Assessment
ZHENG Ke-jun, LI Chen, WU Ying-mei, GAO Bin-pin, WU Yan, LI Chan
2022, 38(11):  1377-1387.  doi:10.19741/j.issn.1673-4831.2021.0816
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The responsibility of maintaining ecosystem circulation and biodiversity protection falls on key ecological function areas. It is of great significance to reveal the spatial-temporal evolution characteristics and influencing factors of habitat quality in key ecological functional areas to maintain regional ecological security and promote the harmonious development between man and nature. Based on ecosystem service value (ESV), habitat vitality and habitat threats, a habitat quality assessment model was introduced to analyze the habitat quality in ecological conservation area in Sichuan-Yunnan provinces from 2000 to 2018, while using the geographical detector model to quantify the impact of natural and social-economy factors. The results indicate that: (1) The overall level of habitat quality in the study area showed an upward trend, particularly in the southern part of the study area. The habitat quality grades were mainly at medium, higher or lower levels, while the trend of which was either from lower to medium or medium to higher. (2) 45.97% of the study area's habitat quality was at stable level, 43.46% showed an upward trend, and 10.57% showed an downward trend. Priority should be given to the latter to avoid further deterioration. (3) It turned out that natural factors such as altitude, temperature, topography and terrain, and the distance from waters, exerted primary influence on the spatial-temporal transfer process of habitat quality in the study area. In addition, impact of social-economy factors such as population density, GDP, distance from cities and towns, and night lighting is increasing. Compared with the effect either of natural factor or social-economy factor, the effect of interaction between natural and social-economy factors has profounder impact. This paper is concerned with illustrating the spatial-temporal evolution of habitat quality in ecological conservation area in Sichuan-Yunnan provinces, as well as providing reference for the construction and management of national key ecological function areas.
Carbon Footprint Analysis of Wheat-maize Production System in Hebei Province
XIAO Guang-min, RU Shu-hua, HOU Li-min, WANG Ce, ZHAO Ou-ya, SUN Shi-you, WANG Ling, LIU Lei, ZHANG Guo-yin
2022, 38(11):  1388-1395.  doi:10.19741/j.issn.1673-4831.2021.0803
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Analysis of carbon (C) footprint and related influence factors were beneficial for providing a theoretical support and scientific basis to low carbon agriculture development in Hebei province. Based on the statistical consumption of fertilizer, pesticide, agricultural film and diesel consumption, irrigation power consumption, sown area and yield of wheat and maize in Hebei Province in 2018, a life cycle assessment (LCA) method was used to calculate the C footprint during winter wheat and summer maize production process, which will provide a theoretical support and scientific basis for the development of low-carbon agriculture. The results show that the C emissions, C sequestration and C footprint of winter wheat were 952×104, 463×104 and 489×104 t CO2 eq in wheat season, and 899×104, 588×104 and 311×104 t CO2 eq in maize season, respectively. The annual total carbon emissions, carbon sequestration and carbon footprint of the province for the 2 crops were 1 851×104, 1 051×104 and 800×104 t CO2 eq, respectively. The C emissions and C footprint of winter wheat were 5.90% and 57.23% higher than that of summer maize, but the C sequestration was 21.26% lower than that of summer maize. The emissions related to irrigation, fertilizer and farmland dominated the CO2 emission, which accounted for 37.00%, 31.17% and 18.69% of the total annual C emissions, respectively. The C sequestration of straw incorporation accounted for 84.78% of the annual C sequestration, which was significantly higher than C sequestration caused by chemical fertilizer application. C emissions contributed by chemical fertilizer and machinery were 49.54% and 43.97%, respectively, and the contribution to cost were both with nearly 40% of the total cost inputs, which are significantly higher than the contribution of other agricultural inputs to carbon emissions and cost. The positive C footprint indicate that wheat-maize production system is the source of carbon emissions. The large amount of irrigation water input and the higher nitrogen fertilizer application are the main reasons for the higher carbon emissions of winter wheat. Therefore, reducing the amount of fertilizer application and reducing water irrigation are the most direct and effective ways to the reducing of C emissions and production costs of winter wheat-summer maize production system in Hebei Province.
Measurements, Spatial Spillover and Influencing Factors of Agricultural Eco-efficiency in Henan Province
YAN Ming-tao, QIAO Jia-jun, QU Meng, HAN Dong
2022, 38(11):  1396-1405.  doi:10.19741/j.issn.1673-4831.2021.0772
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Scientific analysis of the temporal and spatial evolution and impact mechanism of agricultural eco-efficiency has important theoretical and practical significance for achieving sustainable agricultural development and formulating related policies. Taking generalized agriculture as the research object, the super-SBM model was used to measure the agricultural eco-efficiency of 104 districts and counties in Henan Province from 1995 to 2019. The Spatial Durbin Model was used to explore the spillover effects of influencing factors, and the geographic detector was used to analyze its spatial stratification heterogeneity. The results reveal that: (1) The agricultural eco-efficiency of Henan Province showed a step-shaped oscillating downward change trend, and spatially showed agglomeration and heterogeneity. (2) Farmers' income level, per capita sown area and planting structure have a positive and direct effects on the agricultural eco-efficiency of the region; the urbanization rate and agricultural machinery density have a negative direct effects on the agricultural eco-efficiency of the region; Farmers' income level has a significant positive spatial spillover effect on agricultural eco-efficiency in adjacent areas; urbanization rate, fertilizer use intensity and agricultural machinery density have negative spatial spillover effects on agricultural eco-efficiency in adjacent areas. (3) The highly influential factors of agricultural eco-efficiency have been transformed from agricultural resource factors to social and economic factors, and the influence of interaction term is greater than that of a single variable. Based on the given research results, it is suggested that agricultural policies should be formulated with pragmatic attention of the spatial spillover effect and spatial heterogeneity of agricultural eco-efficiency, the exchange and collaboration of resource factors between regions should be strengthened, and characteristic agriculture should be developed with their endowments.
Comparative Analysis of Farmers' Livelihood Resilience before and after Relocation for Poverty Alleviation: A Case Study in the Relocation Site in Zhexiang Town of Zhenfeng County, Guizhou Province
JI Tian-ni, ZHOU Zhong-fa, NIU Zi-hao, ZHANG Jia-shuo
2022, 38(11):  1406-1414.  doi:10.19741/j.issn.1673-4831.2022.0023
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This paper explores farmers' livelihood resilience and its influencing factors before and after the implementation of relocation for poverty alleviation in poverty-stricken Karst areas, which is of great significance to enhance the potential of farmers' livelihood resilience and promote the sustainable development of their livelihood. Based on the data obtained from questionnaire surveys that were carried out among 126 relocated households from 2019 to 2021, a livelihood resilience framework was established by introducing the idea of sustainable livelihood analysis, the livelihood resilience of the relocated households was measured, the farmers' livelihood resilience and its influencing factors before and after the relocation were compared and analyzed, and the relevant measures for promoting the livelihood of relocated households are put forward. The results show that the farmers' livelihood resilience was on an upward trend after they were relocated to the site in Zhexiang Town, with an increase of 25.24% from 2019 to 2021; the variation of famers' livelihood resilience in different dimensions ranks from big to small as follows: learning ability > buffering ability > self-organizing ability; the livelihood resilience of relocated farmers' households is influenced by core factors such as family economic conditions, social security, risk coping abilities etc. The potential of farmers' livelihood resilience was significantly different before and after they were relocated to Zhexiang Town, with different growth trends in different dimensions. The sustainable development of relocated farmers' livelihood can be further promoted by improving their income levels and learning abilities, as well as guaranteeing social security.
Spatial-temporal Pattern and Optimization of the Green Space Ecological Networks in the Ningshao Plain
JIN Ai-bo, ZHANG Shi-yang, WANG Xiang-rong
2022, 38(11):  1415-1426.  doi:10.19741/j.issn.1673-4831.2022.0481
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Ecological networks with high-quality green space can increase regional ecosystem service capacity and biodiversity, as well as support the sustainable growth of urban and rural areas. There is a dearth of study on geographical units with natural elements as the boundary and unique geographical pattern characteristics. There are issues like strong subjectivity and subpar implementation in green space ecological network optimization. Taking Ningshao Plain as an example, the changes of ecological source area, ecological resistance surface and ecological corridor in four periods of 1990, 2000, 2010 and 2020 were compared and analyzed. The spatial and temporal pattern of the green space ecological network is analyzed and recommendations on layout optimization are made in light of the reversibility characteristics and current ecological source area conditions. The results of the study show that: (1)Urbanization has reduced the scale of Ningshao Plain's significant ecological source region by 20% over the past 30 years, and the ecological space exhibits clear characteristics of fragmentation; (2)The original gradient resistance pattern was broken by the high resistance radiation layer structure centered on each city, which significantly reduced the Plain's general biological mobility; (3) The Ningshao Plain's green space ecological network structure shows strong fluctuation and fragility, and the ecological corridor is absent in the west and east of the region; (4)Four significant ecological sources-Juyu Mountain, Yuyao River (Ningbo section), Hutou Mountain, Yushi Mountain near Fenghua, and the eastern coastline section of Hangzhou Bay-have been selected as important ecological sources for restoration. 21 important ecological sources of river and lake systems, hilly woodland and coastal shoreline have been added. A total of 132 ecological corridors totaling 985.8 km in length have been designed. 90 important ecological stepping stones and 252 ecological barrier points to be repaired were screened. Following the optimization, corridor current density and green space ecological network indicators will greatly outperform those from 2020. This research can serve as a guide for improving the ecological network of green spaces in Ningshao Plain and for future research on similar regional ecological networks.
Study on Spatial and Temporal Changes of Vegetation Coverage in Gannan Prefecture Based on Different Geomorphological Zones and Their Influencing Factors
MA Yue, WANG Lu-cang, ZHAO Rui-dong, CHANG Fei
2022, 38(11):  1427-1436.  doi:10.19741/j.issn.1673-4831.2022.0201
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Gannan Tibetan Autonomous Prefecture is situated at the northeastern edge of the Tibetan Plateau, in the transition area between the first and second terraces, with complex and variable landform types and very pronounced differences in vegetation coverage. Based on MODIS EVI data from 2000 to 2018, the spatial and temporal trends of the change of vegetation coverage in different geomorphological zones of Gannan Prefecture and their influencing factors were studied and the results show that: (1) Based on temporal changes, the enhanced vegetation index (EVI) growth trends of the northwestern mountain plateau zones, the eastern mountainous hilly zones, and the southern Mindie Valley zones in Gannan Prefecture between 2000 and 2018 were 0.000 8, 0.001 1, and 0.000 9 a-1, respectively. (2) Based on spatial changes, the fractional vegetation coverage (FVC) of Gannan Prefecture demonstrated a decreasing spatial distribution from southwest to northeast. The mountainous area in the northwest was dominated by high coverage, the mountainous and hilly area in the east was dominated by medium coverage, and the Mindie Valley area in the south showed the alternate distribution of low coverage and high coverage. (3) In Gannan, the proportion of EVI improvement (approximately 54%) is greater than the proportion of degradation (about 37%). The majority of degraded EVI areas are located in the northwestern mountain plateau of Maqu and Luqu and the southern valleys of Diebu. The majority of EVI improvement areas are located in the eastern mountainous and hilly terrain. (4) The EVI influencing factors in various geomorphological zones of Gannan Prefecture are different. In this regard, human activity factors and natural environmental factors are the primary determinants of EVI in the northwestern mountain plateau zones, whereas natural environmental factors are the primary determinants of EVI in the eastern mountainous hilly zones and the southern Mindie valley zones.
Estimation of Vegetation Carbon Source/Sink and Analysis of Its Influencing Factors in Hulun Lake Basin from 2013 to 2020
LI Zhao-hui, SHAN Nan, WANG Qi, LI Wen-jing, WANG Zeng-long, BAO Sa-ru, DOU Hua-shan, AO Wen, PANG Bo, WANG Wen-lin
2022, 38(11):  1437-1446.  doi:10.19741/j.issn.1673-4831.2021.0699
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The terrestrial carbon cycle is an important component for researches on climate change and global carbon cycle. Net ecosystem productivity (NEP) is an essential indicator to quantitatively describe the carbon source/sink capacity of vegetated ecosystems. The grassland ecosystem is an important part of the global terrestrial ecosystem, and the Hulun Lake Basin is a multi-ecosystem area dominated by grassland ecosystem and mixed with farmland, forest and wetland ecosystems. The spatiotemporal variations and drivers of its carbon source/sink are of great significance in the study of ecological environmental protection and restoration as well as the local climate change in this region. Based on Landsat 8 OLI high-resolution satellite remote sensing images, ERA5 climate reanalysis data and land cover data, the spatiotemporal patterns of carbon sinks of different vegetation types in the Hulun Lake basin from 2013 to 2020 and their differences in response to climate factors were estimated using a light use efficiency model and a soil respiration model. The results show that since 2013, the Hulun Lake Basin has been functioning as a carbon sink, while the carbon sequestration capacity decreased, with 58.29% of the regional vegetation NEP showing a decreasing trend and 36.77% of the regional vegetation NEP showing a weak increasing trend. The regional monthly average NEP showed inter-annual variation characteristics of firstly decreasing and then increasing, with a variation range of 8.41-16.44 g·m-2·mo-1, In the watershed, the grassland ecosystem had the highest total carbon sink, about 37 Tg·mo-1, and the farmland NEP was mostly affected by temperature, and the forest ecosystem was influenced by the combination of temperature, precipitation, and radiation. The grassland ecosystem is concurrently affected by temperature and precipitation, while the wetland NEP is not significantly correlated with climate factors.
Characteristics of Energy Balance and Evapotranspiration of Sparse Shrubs in the Northeastern Edge of Ulan Buh Desert
PAN Yu-meng, XIAO Hui-jie, XIN Zhi-ming, JIA Xiao-xiao
2022, 38(11):  1447-1455.  doi:10.19741/j.issn.1673-4831.2021.0715
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Based on the 2019 eddy covariance observations and meteorological observation data, the characteristics of the variation in energy balance and evapotranspiration of the sparse shrub ecosystem in the northeastern edge of Ulan Buh Desert were studied, and its energy closure and distribution were analyzed. The total net radiation during the observation period was 2 758 MJ·m-2, and the diurnal variation of the net radiation showed a single-peak type quadratic curve with obvious seasonal variation characteristics. Each energy component showed changes similar to the net radiation, and the absolute value of each item showed the following order: net radiation > sensible heat flux > soil heat flux > latent heat flux. The sum of soil heat flux was positive, indicating that the soil is a heat sink. The turbulent flux was dominated by sensible heat, which accounted for 62% of net radiation, 4% of latent heat, and 1% of soil heat flux during the observation period. The energy balance closure in the study area was not achieved. The energy closures of the half-hour period and daily average flux calculated by the least square method were 64% and 67%, respectively. The energy balance ratio ranged from 0.54 to 0.73, and the energy closure was 65% during the day and 20% at night. The total evapotranspiration during the observation period was 85.6 mm, which was larger than the total amount of precipitation (79.6 mm). The daily average evapotranspiration intensity was 0.36 mm·d-1. The evapotranspiration changed significantly with the plant growth in different periods, and the monthly cumulative evapotranspiration reached the peak in July.
Selection and Utilization of Microhabitats by Ungulates on the Earthquake Damaged Sites in Autumn
XIANG Jiao, ZHOU Tian-xiang, GUO Zhen-shan, MAO Ze-en, HUANG Jin-yan, ZHANG Jin-dong
2022, 38(11):  1456-1463.  doi:10.19741/j.issn.1673-4831.2022.0181
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To explore the microhabitat selection and utilization characteristics of ungulates in areas experienced earthquake damages, a regular survey of 40 field sites affected by earthquake in Wolong Nature Reserve was conducted from the second year to the 11th year (2010-2019) after the Wenchuan Earthquake. 10 related environmental factors such as altitude, slope, and aspect on the spot were measured. Kernel density analysis was performed to analyze the characteristics of ungulates on microhabitat selection and utilization, and the overlap of niches among species was evaluated. The results show that: (1) The ungulates with high to low utilization frequency of the sites experienced earthquake damages are Chinese goral (Naemorhedus griseus), sambar (Rusa unicolor), Chinese serow (Capricornis milneedwardsii) and tufted deer (Elaphodus cephalophus). The utilization rate of the earthquake-damaged sites by tufted deer increased with vegetation restoration, while the overall utilization rate by Chinese serow decreased. (2) Chinese goral prefers habitats with an altitude of about 2 400 m, large number of woody species, large vegetation coverage and high soil ratio. Chinese serow prefers habitats with altitude of 2 600 m, large number of woody species, small vegetation coverage, and high ratio of bare rock or gravel. The tufted deer prefers habitats with altitude of 2 400-2 600 m, large number of herb species, large vegetation coverage and high soil ratio. The sambar prefers habitats with altitude of 2 100 m, large number of herb species, large vegetation coverage, and high ratio of bare rock or gravel. (3) A high similarity in micro-habitat utilization of earthquake-damaged sites was found between Chinese serow and Chinese goral, and between Chinese goral and tufted deer. The overlap in micro-habitat variables between sambar and Chinese serow, sambar and tufted deer, sambar and Chinese goral is low, and there was a large niche differentiation. By investigating the microhabitat selection characteristics of ungulate species in sites experienced earthquake damages, the study may enrich information about behavioral characteristics of ungulate species in dealing with earthquake damages and support effective species conservation policies and restoration measures after earthquake damages.
Effects of Biochar and Its Skeleton on the Removal of Low Concentration Nitrate in Water by Denitrifiers
CHANG Zhi-lin, WANG Chao-xu, ZHANG Feng, LI Hong-yan, CUI Jian-guo
2022, 38(11):  1464-1472.  doi:10.19741/j.issn.1673-4831.2022.0169
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The purpose of the study is to investigate the effects of rice husk-derived biochar and its skeleton on denitrification and N2O emission. Based on the preparation of biochar skeleton (WBC) and the extract of biochar (BCE) by water-washing method and the enrichment and screening of an anaerobic denitrifier (DB), the microcosm incubation experiment was carried out to explore the removal efficiency of low concentration nitrate (about 10 mg·L-1) in simulated wastewater by DB. N2O and N2O+N2 emission rates were determined, and the dynamic changes of the physicochemical properties and the nitrate reductase and nitrite reductase activities of the simulated wastewater during incubation were also investigated. Results show that N2O emission from the simulated wastewater was entirely caused by microbial pathway. The peak of denitrification rate (N2O+N2 emission rate, in terms of N) of the treatment DB appeared at 48 h, while that of the treatment DB+BC appeared at 36 h, and that of the treatment DB+WBC even appeared at 24 h. The maximum denitrification rates of DB+BC and DB+WBC (44 087.79 and 46 826.27 ng·h-1, respectively) were significantly higher than that of DB (38 097.45 ng·h-1). Compared with DB, the cumulative N2O+N2 emissions of DB+BC and DB+WBC increased by 30.17% and 2.86%, respectively, while the cumulative N2O emissions decreased by 83.04% and 74.52%, respectively, indicating that both BC and WBC increased the denitrification rate and promoted N2O reduction. Compared with DB+BC, the cumulative N2O+N2 emission of DB+WBC decreased by 20.98%, indicating that the denitrification promotion effect of biochar skeleton was not as good as that of biochar, but its conductance structure still played an important role in denitrification.
Pollution Assessment and Source Identification of Heavy Metals in Farmland Soils around a Coal Mine Area in Yunnan Province
ZHAO Jia-yin, YANG Di, YANG Xiang-zhi, ZHANG Ning, LIU Yu, WANG Meng-meng, WU Yun-cheng, CHEN Qiu-hui, TIAN Wei
2022, 38(11):  1473-1481.  doi:10.19741/j.issn.1673-4831.2022.0718
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The research area was located in one of the 100 priority coal mine counties in China. The area is an epitome of China's coal development, and thus is typical and representative. Samples from the soil, dust-fall, agrochemical and coal residue were collected, so as to analyse the soil contamination and the inventory and contribution of main pollutants around the coal mining site. The pollution factor, spatial distribution, and environmental medium of the heavy metals were comprehensively analysed, and statistical methods including homology analysis, profile analysis, principal component analysis, and positive matrix factorization, were combined to investigate the soil contamination and the inventory and contribution of main pollutants. Results show that:(1) 91.00% of samples were contaminated by heavy metals. The rate of soil Cd, Cu, Cr, Ni, Zn, Pb, and As exceeded risk screening values for soil contamination of agricultural land were 86.0%, 15.00%, 14.00%, 19.00%, 12.00%, 6.00%, and 19.00%, respectively. The rate of soil Cd, Zn, Pb and As exceeded risk intervention values for soil contamination of agricultural land were 23.00%, 2.00%, 2.00%, and 3.00%, respectively. (2) Based on the results of pollution source analysis, the heavy metal contamination in the area mainly came from three sources, i. e., soil background, coal mining production, and fertilizer application, which account for 64.20%, 23.10%, and 12.60% of the contamination, respectively. Specifically, the soil background has the highest contribution to Cu, Cr, and Ni, and the corresponding contribution rate was 83.00%, 90.80% and 89.40%, respectively. Coal mining production and fertilizer application have the highest contribution to Cd and As separately, and the corresponding contribution rate were 93.70% and 93.90%. The results could be a reference for heavy metal evaluation and pollution resources quantitative analysis of similar areas. Meanwhile, the study may provide data support for investigating the heavy metal pollution status around coal mine, cutting off the pollution sources, and taking effective measures for farmland safe utilization.
Effects of Sludge Composting to Replace Nitrogen Fertilizer on Cinnamon Soil Fertility, Yield and Quality of Wheat
XU Fu-jin, CHANG Hui-qing
2022, 38(11):  1482-1490.  doi:10.19741/j.issn.1673-4831.2022.0633
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The effects of different proportions of sludge compost as nitrogen fertilizer on fertility characteristics of cinnamon soil and the risk of nutrient leaching caused by excessive application of sludge compost were explored. In this study, field experiments were conducted to set up no nitrogen fertilizer treatment (WN), conventional fertilization treatment (S0) and five treatments with different ratios of sludge compost replacing nitrogen fertilizer (20%, 50%, 100%, 200%, 300%, respectively denoted as S1, S2, S3, S4, S5), and samples of wheat were collected during jointing and maturity stages for analysis. The results show that compared with conventional fertilization treatment, the replacement of nitrogen fertilizer with sludge compost increased soil organic carbon, available phosphorus, available potassium, nitrate nitrogen contents and comprehensive fertility. Substituting nitrogen fertilizer with sludge compost significantly reduced soil pH value and ammonium nitrogen content at jointing stage, and soil ammonium nitrogen content increased significantly at maturity stage, but pH value did not change significantly. Soil total nitrogen content began to increase significantly when 100% nitrogen fertilizer was replaced. After the nitrogen fertilizer was replaced by sludge compost, the single factor index of total nitrogen showed at clean type I, and the soil organic index reached to clean type Ⅱ when sludge compost replaced 100% of nitrogen fertilizer. The partial productivity and nitrogen utilization efficiency of nitrogen fertilizer were the highest under the treatment of replacing nitrogen fertilizer by 20%, which increased by 2.17% and 43.33%, respectively, and the wheat yield was the highest. When the proportion of nitrogen fertilizer replaced by sludge compost did not exceed 100%, the content of starch, protein dry gluten and wet gluten in wheat grains increased compared with that of the conventional fertilization treatment. It can be seen that replacing 20% of nitrogen fertilizer application with sludge compost is not only conducive to the maintenance of soil nutrients and the improvement of nitrogen fertilizer utilization rate, but also the risk of nutrient leaching by sludge compost application is low, and the yield and quality of wheat will not be reduced.
Environmental Impacts Assessment of Large-scale Multi-floor Pig Farming Systems
FANG Zhi-cong, HUHE Tao-li, YUAN Ru-ling, WU Dan, HUANG Xin, YU Zi-xi, LEI Ting-zhou, CHEN Yong
2022, 38(11):  1491-1500.  doi:10.19741/j.issn.1673-4831.2022.0172
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Given the large-scale and intensive development of the livestock industry, attention has become focused on centralized disposal of livestock waste and efficient utilization of biomass resources. To assess the environmental impact of large-scale multi-floor pig farming systems (LMPFSs), the life cycle assessment method was used to analyze the resource, and energy consumption, and environmental impact of the entire process of feed production, pig breeding, and manure treatment of an LMPFS, and the comprehensive benefits of an LMPFS were compared with those of a traditional pig farming system. Results show that in terms of the environmental impact index of each subsystem, manure disposal and resource utilization each accounted for nearly half of the total, whereas feed production, pig breeding, and other subsystems accounted for 60.36%, 24.25%, and 15.39% of the total, respectively. In relation to global warming, the contributions of pig farming and manure treatment subsystems converged, accounting for 32.95% and 44.98%, respectively. Among the contributions to acidification and eutrophication, the manure disposal and resource utilization subsystems contributed the most, accounting for 58.59% and 63.78%, respectively. In terms of energy consumption, the feed production subsystem accounted for 79.58%. In comparison with a traditional pig farming system, the greenhouse gas emissions, area of breeding land, and human resources associated with an LMPFS were reduced by 30.30%, 91.00%, and 72.00%, respectively.