Jianghan Plain Research Articles

Analysis of the Relationship Between IL-10 Gene Polymorphism and Hypertension Susceptibility in Han Nationality in Jianghan Plain

Objective: To analyze the association between interleukin-10 (IL-10) promoter-1082 and -819 polymorphisms and hypertension in Han nationality in Jianghan Plain. Methods: A total of 50 Han patients with hypertension in Jianghan Plain, who were hospitalized in our hospital from March 2018 to April 2018, were selected as the experimental group. 50 healthy Han Chinese people in Jianghan Plain were selected as the control group. After a series of reactions such as genomic DNA extraction and PCR amplification, polymorphisms of IL-10-819 and -1082 were performed using ABI's BAT3.1 sequencing kit. Analysis and analysis of the risk of developing hypertension at each point. Results: There were three genotypes of C/C, C/T and T/T in the IL-10-819 locus. There was no significant difference between the two groups (P>0.05). There were G/G, G/A and A/A genotypes in IL-10-1082 loci in both groups. There was no significant difference between the two groups (P>0.05). Logistic regression analysis showed that compared with IL-10-819C/C genotype, the risk of hypertension in the population carrying IL-10-819C/T and T/T genotypes was OR＝1.19 (95%CI＝0.71~1.05), χ２=0.73, P>0.05, OR＝1.05 (95%CI＝1.01~1.10), χ２=0.96,P>0.05, the difference was not statistically significant (P>0.05). Compared with IL-10-1082A/A, the risk of developing hypertension in the population expressing IL-10-1082G/A and G/G genotypes was OR＝1.2 (95%CI＝0.76~1.12), χ２=0.704, P>0.05, OR＝1.33 (95% CI＝0.77~1.33), χ２=0.97, P>0.05, the difference was not statistically significant (P>0.05). Conclusion: The distribution of genotypes and alleles of IL-10-819 and -1082 loci in Han patients with hypertension and healthy people in Jianghan Plain is similar, and the genotype mutations of IL-10-819 and -1082 are irrelevant with hypertension.

Building a New Framework for Evaluating the Livability of Living Space on the Basis of the Daily Activities of Rural Residents: A Case Study of Jianghan Plain.

The evaluation of the livability of rural living spaces is an important aspect of rural sustainable development, which is related to the well-being of rural residents. This study proposes a new evaluation framework for assessing the livability pattern of rural living spaces from the major components of the daily activities of rural residents. It fully considers whether the living space within a certain geographical area can meet the needs of rural residents in terms of residence, employment, consumption, leisure, and other types of daily activities. This study also establishes a comprehensive index system that includes 36 indicators and develops a comprehensive assessment method for evaluating the livability pattern of rural living spaces. Moreover, this research conducts a case study on the spatial pattern of rural living spaces in China’s Jianghan Plain in 2018. We determine that the livability of rural living spaces in Jianghan Plain exhibits an evident “grade difference” characteristic. The overall livability level is not high. Seven problem counties from three categories are delineated on the basis of the score status. The new framework and conclusions of this study are conducive to the future targeted construction of livable rural living spaces.

Spatio-Temporal Variation and Influencing Factors of the Coupling Coordination Degree of Production-Living-Ecological Space in China.

Territorial space is a multi-functional complex. The coordinated production-living-ecological space (PLES) effectively coordinates the man-land relationship, promotes regional sustainable development, and maximizes territorial space. How to build a high-quality national spatial layout and support system for development has become a hot topic of concern in all sectors of society. However, few studies have explored the coupling coordination considering the various production-living-ecological functions of land use type and its influencing factors of PLES at the county scale in China. To address the gap, based on the connotation of PLES theory, this study established a classification and evaluation system for PLES and analyzed the spatio-temporal characteristics, coupling coordination degree, spatial autocorrelation, and influencing factors of PLES in China from 2000 to 2020. The results are as follows: (1) The production space index and living space index in China showed a continuous increase tendency, while the ecological space indexs decreased continuously during the study period. The production space and living space were concentrated in the east of Hu Line, and the ecological space indexes in mountainous areas were significantly higher than those in plain areas during the study period. (2) The gravity centers of PLES all migrated to the west of China to different degrees during the study period. (3) From 2000 to 2020, the basically balanced category was the main coupling coordination type, and the number of seriously unbalanced categories accounted for the least. In the west of the Hu Line, the seriously unbalanced category was dominant, while in the east of the Hu Line were the moderately unbalanced categories and above. (4) During the study period, the low-low type was the main relationship type, widely distributed in western China, followed by the high-high type, mainly situated in the North China Plain, Yangtze River Delta, Pearl River Delta, Jianghan Plain, Chengdu Plain, Northeast China Plain, and some provincial capital cities. (5) Regression results showed that natural factors were the main reason restricting the coordinated development of PLES, and socioeconomic factors could effectively promote the coordinated development of PLES. Landscape pattern also significantly influenced the coordinated development of PLES, but varied greatly. The findings of this study can provide a scientific reference for the optimization of territorial space layout and the promotion of high-quality development of territorial space.

Satellite Imagery-Based Identification of High-Risk Areas of Schistosome Intermediate Snail Hosts Spread after Flood

Snail intermediate host monitoring and control are essential for interrupting the parasitic disease schistosomiasis. Identifying large-scale high-risk areas of snail spread after floods has been greatly facilitated by remote sensing imagery. However, previous studies have usually assumed that all inundation areas carry snails and may have overestimated snail spread areas. Furthermore, these studies only used a single environmental factor to estimate the snail survival risk probability, failing to analyze multiple variables, to accurately distinguish the snail survival risk in the snail spread areas. This paper proposes a systematic framework for early monitoring of snail diffusion to accurately map snail spread areas from remote sensing imagery and enhance snail survival risk probability estimation based on the snail spread map. In particular, the flooded areas are extracted using the Sentinel-1 Dual-Polarized Water Index based on synthetic aperture radar images to map all-weather flooding areas. These flood maps are used to extract snail spread areas, based on the assumption that only inundation areas that spatially interacted with (i.e., are close to) the previous snail distribution regions before flooding are identified as snail spread areas, in order to reduce the misclassification in snail spread area identification. A multiple logistic regression model is built to analyze how various types of snail-related environmental factors, including the normalized difference vegetation index (NDVI), wetness, river and channel density, and landscape fractal dimension impact snail survival, and estimate its risk probabilities in snail spread area. An experiment was conducted in Jianghan Plain, China, where snails are predominantly linearly distributed along the tributaries and water channels of the middle and lower reaches of the Yangtze River. The proposed method could accurately map floods under clouds, and a total area of 231.5 km2 was identified as the snail spread area. The snail survival risk probabilities were thus estimated. The proposed method showed a more refined snail spread area and a more reliable degree of snail survival risk compared with those of previous studies. Thus, it is an efficient way to accurately map all-weather snail spread and survival risk probabilities, which is helpful for schistosomiasis interruption.

Recognition and Changes Analysis of Complex Planting Patterns Based Time Series Landsat and Sentinel-2 Images in Jianghan Plain, China

Accurate and timely information on crop planting patterns is crucial for research on sustainable agriculture, regional resources, and food security. However, existing spatial datasets have few high-precision and wide-range planting pattern maps. The production may be limited by the unbalanced spatiotemporal resolution, insufficient massive field sample data, low local computer processing speed, and other factors. To overcome these limitations, we proposed semi-automatic expansion and spatiotemporal migration strategies for sample points and performed a pixel-and-phenology-based random forest algorithm on the Google Earth Engine platform to generate crop planting pattern maps at high spatiotemporal resolution by integrating Landsat-8 and Sentinel-2 time series image data. In this study, we report planting pattern maps for 2017–2021 at a 10-m spatial resolution of the Jianghan Plain, including six crops and nine planting patterns, with an overall accuracy of 84–94% and a kappa coefficient of 0.80–0.93. The spatiotemporal distribution is driven by multiple factors, such as subjectivity and social economy. This research indicates that the proposed approach is effective for mapping large-scale planting patterns and can be readily applied to other regions.

Mapping Soil Organic Carbon in Low-Relief Farmlands Based on Stratified Heterogeneous Relationship

Accurate mapping of farmland soil organic carbon (SOC) provides valuable information for evaluating soil quality and guiding agricultural management. The integration of natural factors, agricultural activities, and landscape patterns may well fit the high spatial variation of SOC in low-relief farmlands. However, commonly used prediction methods are global models, ignoring the stratified heterogeneous relationship between SOC and environmental variables and failing to reveal the determinants of SOC in different subregions. Using 242 topsoil samples collected from Jianghan Plain, China, this study explored the stratified heterogeneous relationship between SOC and natural factors, agricultural activities, and landscape metrics, determined the dominant factors of SOC in each stratum, and predicted the spatial distribution of SOC using the Cubist model. Ordinary kriging, stepwise linear regression (SLR), and random forest (RF) were used as references. SLR and RF results showed that land use types, multiple cropping index, straw return, and percentage of water bodies are global dominant factors of SOC. Cubist results exhibited that the dominant factors of SOC vary in different cropping systems. Compared with the SOC of paddy fields, the SOC of irrigated land was more affected by irrigation-related factors. The effect of straw return on SOC was diverse under different cropping intensities. The Cubist model outperformed the other models in explaining SOC variation and SOC mapping (fitting R2 = 0.370 and predicted R2 = 0.474). These results highlight the importance of exploring the stratified heterogeneous relationship between SOC and covariates, and this knowledge provides a scientific basis for farmland zoning management. The Cubist model, integrating natural factors, agricultural activities, and landscape metrics, is effective in explaining SOC variation and mapping SOC in low-relief farmlands.

Rice Paddies Reduce Subsequent Yields of Wheat Due to Physical and Chemical Soil Constraints.

Yields of wheat crops that succeed rice paddy crops are generally low. To date, it has been unclear whether such low yields were due to rice paddies altering soil physical or mineral characteristics, or both. To investigate this quandary, we conducted field experiments in the Jianghan Plain to analyze differences in the spatial distribution of wheat roots between rice-wheat rotation (RW) and dryland-wheat rotations (DW) using a range of nitrogen treatments. Dryland wheat crops were preceded by either dryland soybean or corn in the prior summer. Biomass of wheat crops in RW systems was significantly lower than that of DW for all N fertilizer treatments, although optimal nitrogen management resulted in comparable wheat yields in both DW and RW. Soil saturated water capacity and non-capillary porosity were higher in DW than RW, whereas soil bulk density was higher in RW. Soil available nitrogen and organic matter were higher in DW than RW irrespective of N application, while soil available P and K were higher under RW both at anthesis and post-harvest stages. At anthesis, root length percentage (RLP) was more concentrated in surface layers (0–20 cm) in RW, whereas at 20–40 cm and 40–60 cm, RLP was higher in DW than RW for all N treatments. At maturity, RLP were ranked 0–20 > 20–40 > 40–60 cm under both cropping systems irrespective of N fertilization. Root length percentage and soil chemical properties at 0–20 cm were positively correlated (r = 0.79 at anthesis, r = 0.68 at post-harvest) with soil available P, while available N (r = −0.59) and soil organic matter (r = −0.39) were negatively correlated with RLP at anthesis. Nitrogen applied at 180 kg ha−1 in three unform amounts of 60 kg N ha−1 at sowing, wintering and jointing resulted in higher yields than other treatments for both cropping systems. Overall, our results suggest that flooding of rice paddies increased bulk density and reduced available nitrogen, inhibiting the growth and yield of subsequent wheat crops relative to rainfed corn or soybean crops.

Evolution of the groundwater flow system driven by the sedimentary environment since the Last Glacial Maximum in the central Yangtze River Basin

• Fluctuations in the Yangtze River and sedimentary environment control GFS evolution. • Sedimentary evolution caused unconformable distribution of groundwater age in a GFS. • Continuous uplift of discharge base level favors preservation of ancient groundwater. • Holocene fine-grained sedimentary strata led to the stagnation of regional GFS. Understanding the circulation and evolution of groundwater and its control mechanism in the Jianghan Plain, which exhibits the complex sedimentary evolution and a progressively deteriorating groundwater environment, is highly imperative and challenging to promote the practical application of groundwater flow system (GFS) and protect the groundwater resources in the region. The aim of this work was to elucidate the evolution pattern of the GFS in the Jianghan Plain and its underlying mechanism. To this end, the grain size characteristics of sediments, geochronological information, stable isotopes in clay porewater, paleoclimate indicators, and existing groundwater age were analyzed to reveal the sedimentary environment of aquifer systems at the basin scale in the study area. It was found that the sedimentary environment changed from one of deep downcutting during the Last Glacial Maximum (LGM) to a fluvial facies that was rapidly infilled with coarse-grained sediments during the last deglaciation period (LDP), and then to a stable lacustrine facies with fine-grained sediments during the Holocene warm period (HWP). These changes were closely linked to the fluctuations of the Yangtze River. Consequently, the existing GFS pattern in the basin presents an unconformable distribution of groundwater age, indicating that it results from the temporal superposition of groundwater flow controlled by the historical sedimentary environment. Dramatic sea level fluctuations since the LGM have resulted in significant changes in the water level of the Yangtze River. This process has impacted the driving force of groundwater, resulting in the evolution of the GFS from a pattern of a fully developed regional GFS during the LGM to the present pattern of a multi-hierarchy nested GFS.

Effect of pollution load reduction on water quality in rural lakes in the shallow hill water network area

Abstract There is poor water environment quality in rural lakes in the shallow hill water network area north of the Han River on the Chinese Jianghan Plain due to their poor hydrodynamic conditions. We herein selected ten typical rural lakes to simulate water environment improvement. The hydrodynamic and water quality models were built based on MIKE21, while the simulation compared the year-round trends in lake water quality in the current and planning year, and demonstrated the possibility of recharging rural lakes from the backbone of the Han River–Three Inland Rivers networks. The results show that the water quality of the ten lakes has improved significantly after pollution control, with an improvement rate of more than 70%. Pollution interception and management are particularly successful for improving lake water quality in rural lakes. The replenishment of water from the backbone river to the lakes could enhance the fluidity of the rural lakes but cannot eliminate the total phosphorus (TP) risk. Therefore, in the relatively closed water bodies of rural lakes in the shallow hilly water network area, pollution intercept and control is key to controlling TP, and taking measures such as increasing lake hydrodynamic conditions in summer will be a more efficient approach to improve rural lake water quality.

Optimizing the spatial pattern of land use in a prominent grain-producing area: A sustainable development perspective

Spatial patterns are essential for examining the sustainability derived from land systems. Constructing spatial patterns for sustainable land development is now high on the global agenda to guarantee human welfare. However, there is as yet no consensus on the comprehensive framework for optimizing the spatial pattern of land development (SPLD) contrapose a prominent grain-producing area (PGPA). To narrow this gap, we propose a synthetic framework to shape a more reasonable SPLD for a sustainable development strategy by measuring the equilibrium between the production–living–ecological space (PLES) functions and the resource and environment carrying capacity (RECC). Taking a prominent grain-producing area (PGPA) as the object, a case study involving the Jianghan Plain (JHP) in China is conducted, leading to the following novel insights. (i) The quality of PLES and RECC in a PGPA is affected by multiple dimensions: agriculture, ecology, environment, and society. The indices of the PLES function and the RECC have significant spatial heterogeneity. SPLD in regions with fragile ecological environments and strong development is often under overload pressure. (ii) Based on the spatial zoning results of SPLD, the five partitions were taken as the optimized objects, including zones of the eco-economic, model-agricultural, core-living, eco-conservation, and coordinated-development. The land function definition of these five types of zoning covers the production-living-ecological function orientation in a PGPA. (iii) The SPLD optimization framework proposed above has strong universality because it comprehensively considers the multi-dimensional spatial functional needs of PGPA. In this study, an optimization decision framework of SPLD based on measurement and zoning was established for a PGPA. Significantly, the introduced framework is applicable and practical for optimizing SPLD from a sustainable equilibrium perspective, and the findings have considerable implications for sustainable development in prominent grain-producing areas.

Spatiotemporal Differentiation and Balance Pattern of Ecosystem Service Supply and Demand in the Yangtze River Economic Belt.

Analyzing the supply and demand of ecosystem services and the regional balance pattern is an important basis for improving the ecological management level. Taking the Yangtze River economic belt as the study area, the spatiotemporal characteristics and balance pattern of ecosystem service supply and demand are quantitatively revealed based on equivalent factors, supply and demand balance modeling and quantile regression. The results show that: (1) the ecosystem services value in the research area experienced a change process of “increase–decrease–increase” from 2000 to 2020. The ecological service value of cultivated land and grassland presented a continuous decline, with decreases of 20.446 billion and 4.53 billion yuan, respectively, in the past 20 years, with reduction rates of −4.82% and −3.98%, respectively. (2) The demand for ecosystem services showed an unbalanced and phased growth trend. The total demand for ecosystem services showed heterogeneity and agglomeration effects in space. High demand and higher demand areas are mainly distributed in the regions with relatively developed population and economy, including Yangtze River Delta urban agglomeration, “Changsha–Zhuzhou–Xiangtan” urban agglomeration, Poyang Lake Plain, Jianghan Plain and Chengdu Plain. (3) The overall pattern of the supply–demand balance of ecosystem services has changed little; however, there have also been significant changes in certain areas in individual years.

Geostatistical analysis and hydrofacies simulation for estimating the spatial variability of hydraulic conductivity in the Jianghan Plain, central China

Geostatistical analysis and hydrofacies simulation for estimating the spatial variability of hydraulic conductivity in the Jianghan Plain, central China

Evaluation of Temporal and Spatial Changes in Ecological Environmental Quality on Jianghan Plain From 1990 to 2021

Located in the middle reaches of the Yangtze River, Jianghan Plain is an important part of the middle and lower reaches of the Yangtze River Plain, and together with Dongting Lake Plain, it is known as the Two-Lake Plain. It is a well-developed agricultural area and is an important source of grain in China, as well as one of the major cotton-producing areas, and aquaculture is also an important local industry. With the rapid development of urbanization in China, the impact of human activities on the ecological environment of Jianghan Plain has become increasingly obvious in recent years, and how to timely and objectively assess spatial and temporal changes in ecological environmental quality is of great practical significance for the sustainable development of the region and the construction of an ecological civilization. The Google Earth Engine platform was used to optimize the reconstruction of Landsat TM/OLI images of Jianghan Plain from 1990 to 2021, coupled with four indicators of the natural ecological environment such as the Normalized Difference Vegetation Index, WET, Normalized Difference Soil Index, and Land Surface Temperature to construct the remote sensing ecological index (RSEI) and evaluate the spatial and temporal changes in ecological environmental quality on Jianghan Plain. The results showed that the mean RSEI values in 1990, 1998, 2006, 2014, and 2021 were 0.667, 0.636, 0.599, 0.621, and 0.648, respectively, indicating that the overall ecological environmental quality of Jianghan Plain showed a decreasing trend from 1990 to 2006 and an increasing trend from 2006 to 2021. Degradation was most serious from 1990 to 1998, accounting for 44.86% of the total area, and improvement was most obvious from 2006 to 2014, accounting for 26.64% of the total area. Moran’s I values from 1990 to 2021 were 0.531, 0.529, 0.525, 0.540, and 0.545, respectively, indicating that the spatial distribution of ecological environmental quality was positively correlated. The local spatial clustering of the RSEI local indicators of spatial association showed that H-H clustering areas on Jianghan Plain were mainly distributed in the northern and western regions, and L-L clustering areas were mainly distributed in the densely populated eastern regions with frequent human activities. The results can provide a theoretical basis for ecological environmental protection and improvement on Jianghan Plain.

Changes in everyday life of rural China: a perspective of mobilities

This article aims to examine how rural everyday life has changed in the Chinese context in response to the process of urbanisation. Drawing on a mobilities perspective, changes in everyday life are represented by spatial mobilities and the impacts of social mobilities on them are assessed at a household level. Employing rural survey data for 2007 and 2017 conducted in Jianghan Plain, China, results reveal that everyday life in central rural China has undergone an uneven development and is significantly impacted by social mobilities. As one of the main agricultural production regions in China, the livelihood strategies in the study area have been shifting from full-time farming to part-time farming and non-farm. The effects of the process of social mobilities on working, consuming and leisure mobilities are also unevenly distributed. Our findings suggest that the perspective of everyday life deserves further investigation for its important role in exploring the human–land relationship in a rural context. And the mobilities paradigm can provide an alternative insight into rural restructuring and its social effects.

Sources and transformations of nitrogen in an agricultural watershed on the Jianghan Plain, China: an integration of δ15N–NH4+, δ15N–NO3-, δ18O–NO3- and a Bayesian isotope mixing model

Due to the complexity of nitrate sources and transformation processes under extensive human activities and climate change, there are a great number of uncertainties associated with ascertaining nitrogen sources and transformations in agricultural watersheds. In this study, multiple isotopes of ammonium (δ15N–NH4+), nitrate (δ15N–NO3-, δ18O–NO3-), water (δ18O–H2O) and hydrogeochemical data were integrated to identify nitrogen sources and elucidate the mechanisms of nitrogen transformation in the Quanshui River watershed, a typical agricultural watershed in central China. The characteristics of nitrate nitrogen and oxygen isotopes, lower δ15N–NO3- values (<9.73‰), and the results from the Bayesian isotope mixing model showed that the main sources of nitrogen in the watershed were mostly ammonium fertilizers (AF), nitrate fertilizer (NF) and soil organic nitrogen (SON). In the fertilization season, the enrichment of δ15N–NH4+ and the negative correlation between δ15N–NH4+ and δ15N–NO3- indicated that the volatilization and partial nitrification of nitrate in chemical fertilizers were the main factors affecting nitrogen isotope changes in the water. Seasonal changes in δ15N–NH4+ and δ15N–NO3- values can provide more direct isotopic evidence for the occurrence of nitrification, which may provide more useful insights into nitrogen transformation in future studies. Seasonal variations in δ18O–NO3- can effectively indicate the impact of rainfall events on the nitrogen cycle.

Modeling farmers’ adoption of low-carbon agricultural technology in Jianghan Plain, China: An examination of the theory of planned behavior

Low-carbon agricultural technology (LCAT) has a fundamental role for China to reach the carbon emissions peak in 2030 and achieve carbon neutrality in 2060. Using data obtained from questionnaires completed by 386 small farmers in Jianghan Plain, China, we construct a theoretical framework based on the theory of planned behavior and structural equation model to elicit the determinants affecting farmers’ adoption of LCAT. Three notable results emerge. (1) Farmers’ behavioral attitude (BA), subjective norm (SN), and perceived behavioral control (PBC) were correlated. (2) Farmers’ behavioral intention (BI) to adopt LCAT was significantly and directly affected by BA, SN, and PBC, and BA had the highest impact (0.62). (3) Farmers’ BA and BI both impose positively significant effects on behavioral response (BR) regarding LCAT, and the BI had the strongest impact (0.53). Based on these findings, future policy interventions to promote LCAT measures should focus on improving farmers’ knowledge of LCAT, upgrading the promotion tools of LCAT, and emphasizing the exchange of technical information among farmers.

Assesmment of precipitation suitable degree from integrated rice-crayfish farming systems in Jianghan Plain of China

In recent 10 years, an integrated rice-crayfish farming (IRF) has been developing rapidly in the middle and lower reaches of the Yangtze River in China, and produced significant economic and ecological benefits. However, the IRF mode consumes a large amount of water and brought a great risk of water shortage. In Jianghan Plain, Hubei province, China, there are 4 IRF modes, referring to rotation of rice and crayfish (RRC), rice-crayfish symbiosis (RCS), year-round crayfish farming in paddy fields (YRC), and continuous operation of rice planting and crayfish farming (COR). This study selected the 4 IRF modes to calculate and compare the precipitation suitable degree (PSD) of 17 counties with larger scale of IRF. The results showed that, annual PSD for different IRF modes varied greatly for same county and among different counties, the annually averaged PSD was from 0.52 to 1.06 from the northern to southern Jianghan Plain. Annually averaged PSD from large to small was ranked as RCS&gt;COR&gt;RRC&gt;YRC. The PSD values of IRF was different among different months, and the highly suitable period for PSD was from March to July, and the precipitation of each county (city) fully meet the water demand of rice growth and crayfish farming. In August thorogh November, the spatial distribution of PSD showed largely variation, and the monthly PSD was lower in the northern Plain, and slightly higher in the southern. From December to the next February, the PSD was obviously lower than other stages, even in the south of Jianghan Plain, with high risk of water deficit at the stage. According to the water demand regulation of the 4 IRF modes, the suitable IRF mode was RRC and YRC for the south, and RCS and COR for the north of Jianghan Plain in China. Considering long term negative affects for flooded paddy field, the paddy field used for RCS or COR mode should be changed to other farming system for 1 year or 2 years, such as IRF replaces with rice and wheat (oilseed rape) rotation for 1 year or 2 years after IRF was conducted for 5 years, so as to avoid exacerbating soil gleying.

A Geographic Analysis on Rural Reconstruction-Transformation-Revitalization: A Case Study of Jianghan Plain in China

At the beginning of the 21st century, with the rapid advancement of industrialization and urbanization, production factors such as population, capital, and land between urban and rural areas in China have gradually shifted to non-agricultural fields, the structure and function of rural territorial systems have been reconstructed and transformed therewith. In response to the relatively declining villages, the Chinese government proposed rural revitalization strategy. Taking the human–land relationship as the theoretical basis and functional changes of rural region as the main line, the study analyzes the characteristics of rural reconstruction, interprets the rural transformation mechanism and deconstructs paths of rural revitalization by using the rural reconstruction index, the model of rural transformation measurement and rural spatial transformation effect. The case study shows that: (1) Rural reconstruction in Jianghan Plain is characterized by temporal continuity and spatial imbalance. The periodical changes presents from social-reconstruction-dominated, economic-reconstruction-dominated to spatial reconstruction -dominated. The distribution of high values varied from the U-type to O-type along the main transportation routes, while that of low values alternated between points (hinterlands of the Plain) and lines from spatial viewpoint. (2) The driving mechanism of rural transformation was the coupling effect of the exogenous drivers and endogenous responses. The standardized regression coefficient between the drivers and the changes to rural regional functions is 0.766. The endogenous response is mainly manifested as the negative effect of the rural spatial reconstruction on the territorial agriculture-oriented function. (3) The key path of rural revitalization facilitated the optimization of regional functions through reorganization of the rural elements in Jianghan Plain. It is the strategic choice of rural areas to implement regional function zoning and realize the balance of spatial function. The research results can provide inspiration for theoretical research on rural geography, and provide policy and method support for rural revitalization in case areas.

Dynamic characteristics of net anthropogenic phosphorus input and legacy phosphorus reserves under high human activity - A case study in the Jianghan Plain

The increase of phosphorus (P) input related to human activities is one of the main reasons for eutrophication. Notably, in areas with high population densities and intensive agricultural activities, eutrophication has occurred frequently in the Jianghan Plain, so quantitative evaluation of anthropogenic P input is of great significance for the formulation of P pollution control measures. This study estimated net anthropogenic P input (NAPI), riverine total P exports (TP exports), and the pool of P stored in the terrestrial system (legacy P reserves) at the county scale from 1990 to 2019 in the Jianghan Plain. The results showed that NAPI increased from 2645 kg·km−2·yr−1 in 1991 to 5812 kg·km−2·yr−1 in 2014, and then decreased to 4509 kg·km−2·yr−1 in 2019. Non-point sources were the main form of NAPI, of which 75–96% came from agricultural systems. Meanwhile, P fertilizer input was the largest source of NAPI. It is worth noting that the contribution of seed P input in some counties, such as Jiangling County, is relatively high, even exceeding that of net food/feed P input. The P fertilizer application and livestock density were the main drivers for NAPI change. Only 3% of NAPI was exported into rivers, so a large amount of legacy P accumulated in the terrestrial system. An empirical model incorporating NAPI components, cultivated land area ratio, and annual precipitation was established. Based on this model, the average contribution of annual NAPI and the sum of legacy P and natural background sources to TP exports were calculated to be 71% and 29%, respectively. So it is necessary to control P pollution by improving fertilizer use efficiency and enhancing manure management. The results provide a scientific basis for targeted solutions to the sources of P nutrient and its control measures in the middle reach of the Yangtze River.

How Does Crop Rotation Influence Soil Moisture, Mineral Nitrogen, and Nitrogen Use Efficiency?

Rice–wheat (RW) cropping systems are integral to global food security. Despite being practiced for decades, Chinese RW cropping systems often suffer from low productivity and poor nitrogen use efficiency (NUE), reflecting management approaches that are not well-contextualized to region and season. Here, we develop the best management guides for N fertilizer in RW systems that are designed to help raise the productivity, NUE, and environmental sustainability of winter wheat over the long term. 2-year field experiments were conducted with four N fertilizer rates (0, 135, 180, and 225 kg N ha–1), allowing contrasts of yields, soil moisture, and NUE of wheat in RW in the humid climates zones on the Jianghan Plain. We compared RW systems with soybean/maize dryland wheat (DW) systems that are similarly endemic to China: after soybean/maize is harvested, soils are often drier compared with moisture content following rice harvest. With high seasonal N application rates (180–225 kg N ha–1), wheat crop yields increased by 24% in RW which were greater than comparable yields of wheat in DW, mainly due to greater kernels per spike in the former. Across treatments and years, N accumulation in plant tissue and kernel dry matter of DW was higher than that in RW, although mean agronomic efficiency of nitrogen (AEN) and physiological efficiency of nitrogen (PEN) of RW systems were greater. As N application rates increased from 135 to 225 kg ha–1, AEN and PEN of DW decreased but changed little for RW. Soil ammonium N was much lower than that of nitrate N; changes in NH4+ and NO3– as a consequence of increasing N fertilization were similar for RW and DW. We recommend that tactical application of N fertilizer continue seasonally until midgrain filling for both the DW and RW systems. At fertilization rates above 180 kg N ha–1, yield responses disappeared but nitrate leaching increased significantly, suggesting declining environmental sustainability above this N ceiling threshold. Collectively, this study elicits many functional and agronomic trade-offs between yields, NUE, and environmental sustainability as a function of N fertilization. Our results show that yield and NUE responses measured as part of crop rotations are both more robust and more variable when derived over multiple seasons, management conditions, and sites.