Functional Zoning and Path Selection of Land Comprehensive Consolidation Based on Grey Constellation Clustering: A Case Study of Dongying City, China.

The functional zoning of land comprehensive consolidation and the selection of consolidation paths are the key content of the current land and space planning, and it is also an important measure to achieve regional sustainable development. At present, the research system on land comprehensive consolidation is not yet mature. The previous research area is relatively small and not representative, and an effective method system has not been formed. Research on the selection of functional zoning and a consolidation path is also relatively scarce. There is an urgent need to construct the theory and method system of land comprehensive consolidation functional zoning and consolidation path selection. Taking Dongying City in China as an example, this paper constructs a zoning index system from four aspects including natural conditions, location advantages, social economy and land use. The entropy method is used to determine the weights, and GIS spatial data visualization is used to analyze the spatial distribution characteristics of the index system. Based on the analysis, the grey constellation clustering method is used to divide the study area into four types of land comprehensive consolidation functional areas, and the results of functional zoning are adjusted according to the ranking of comprehensive index values, the principle of maximum similarity, and the continuity of natural space. The research results show that: ① There are 10 functional zonings for urban development and ecological protection land consolidation, and the main consolidation path should be the ecological country park consolidation model, which can effectively serve the urban ecological construction. ② There are nine functional zonings for rural development and cultivated land conservation consolidation, and their consolidation path should be based on a comprehensive rural improvement model that enhances the quality of the village and the development, utilization and protection of cultivated land resources. ③ There are 18 functional zonings for cultivated land improvement and ecological protection land consolidation, and the main consolidation path should focus on the cultivated land ecological improvement mode that emphasizes the quality of cultivated land and the improvement of regional ecological functions. ④ There are four functional zonings for ecological conservation and fallow recuperative land consolidation, and their main consolidation path should be the land ecological restoration and improvement model of construction land reclamation, cultivated land ecological conservation, and conversion of farmland to forest and grassland. The research results can provide references for Dongying City to formulate land and space planning, and can be extended to the design of comprehensive land remediation projects in other regions. It is of great significance to promote regional sustainable and scientific development.

Effect Mechanism of Land Consolidation on Soil Bacterial Community: A Case Study in Eastern China.

Farmland consolidation is an effective tool to improve farmland infrastructures, soil quality, and sustain a healthy farmland ecosystem and rural population, generating contributions to food security and regional sustainable development. Previous studies showed that farmland consolidation regulates soil physical and chemical properties. Soil microorganisms also play an important role in soil health and crop performance; however, few studies reported how farmland consolidation influence soil microecology. Here, we used DNA sequencing technology to compare bacterial community structure in farmlands with and without consolidation. DNA sequencing technology is the most advanced technology used to obtain biological information in the world, and it has been widely used in the research of soil micro-ecological environment. In September 2018, we collected soil samples in Jiashan County, Zhejiang Province, China, and used DNA sequence technology to compare the bacterial community structure in farmlands with and without consolidation. Our results found that (1) farmland consolidation had significant impacts on soil microbial characteristics, which were mainly manifested as changes in microbial biomass, microbial diversity and community structure. Farmland consolidation can increase the relative abundance of the three dominant bacteria phyla and the three fungal dominant phyla, but it also negatively affects the relative abundance of the six dominant bacteria phyla and the three fungal dominant phyla. (2) Farmland consolidation had an indirect impact on soil bacterial community structure by adjusting the soil physical and chemical properties. (3) The impact of heavy metals on bacterial community structure varied significantly under different levels of heavy metal pollution in farmland consolidation areas. There were 6, 3, 3, and 5 bacterial genera that had significant correlations with heavy metal content in cultivated land with low pollution, light pollution, medium pollution, and heavy pollution, respectively. The number of heavy metal-tolerant bacteria in the soil generally increased first and then decreased under heavy metal polluted conditions. Our study untangled the relationship between varied farmland consolidation strategies and bacteria through soil physcicochemical properties and metal pollution conditions. Our results can guide farmland consolidation strategies and sustain soil health and ecological balance in agriculture.

Adaptation of soil fungi to heavy metal contamination in paddy fields-a case study in eastern China.

Soil fungi have been widely studied, but the effects of heavy metal contamination at various levels as well as the abundance and diversity of heavy metal tolerant fungi in the contaminated paddy soils are still unknown. The purpose of this study is to analyze the adaptability of fungi at different levels of heavy metal contamination to identify species that have strong adaptability to heavy metals. In this research, the technology of high-throughput sequencing was applied to study fungal communities in severe level (SL), moderate level (ML), light level (LL), and clean level (CL) for soil samples polluted by heavy metal, as well as to analyze the relations between environmental variables and fungal communities. The spearman analysis showed that 6 dominant fungal phyla and 18 dominant fungal genera were significantly correlated with these environmental variables. The α-diversity indexes of the soil fungal community from SL, ML, and CL were, mostly, drastically higher than the LL samples (p < 0.05). Meanwhile, Ascomycota, the main fungal phylum, was spotted to yield a strong tolerance towards heavy metals, especially in ML. The most dominant genera of tolerant fungi in this area, which are Aspergillus, Penicillium, and Fusarium, could absorb and transport the heavy metals with the help of nutrients under certain heavy metal contamination levels. Therefore, this study indicated that some fungi, which have strong biodegradability on heavy metals, can reduce toxicity of heavy metals and create a proper soil environment to grow food crops. Graphical abstract.

Driving factors of total-factor substitution efficiency of chemical fertilizer input and related environmental regulation policy: A case study of Zhejiang Province.

Based on the panel data of 63 counties of Zhejiang Province from 2003 to 2017, this paper studied the total-factor substitution efficiency of chemical fertilizer input and its spatial-temporal evolution by using the Super-efficiency DEA(Data Envelopment Analysis) model, locational Gini coefficient and Theil index. And the driving factors of the total-factor substitution efficiency of chemical fertilizer input were analyzed by constructing the Panel Tobit model. The results showed that: the comprehensive efficiency of total-factor substitution for chemical fertilizer input in Zhejiang Province is low, and technical efficiency is the main drive for promoting comprehensive efficiency; Gini coefficient is below the warning line of 0.4, and the difference of substitution efficiency, relatively small, mainly comes from the contribution within the region, and the difference ratio of contribution by the Southwestern Zhejiang is rapidly increasing. In detail, financial investment in agriculture serve as the greatest the driving force, and government chemical fertilizer input subsidies have a significantly negative effect. Therefore, we should improve the subsidy policy system, increase government investment in agricultural infrastructure, adjust the structure of agroindustry and improve the income of rural residents under the premise of reducing the fertilizer input intensity.

Comprehensive assessment of paddy soil quality under land consolidation: a novel perspective of microbiology.

Soil quality assessment is an important means to demonstrate how effective land consolidation is. However, the existing assessment system is not sufficient to reflect actual soil quality. So, the purpose of this study is to integrate abiological and biological indicators into a comprehensive assessment to evaluate the paddy soil quality under different land consolidation practices. Soil samples were collected from 35 paddy sites under different land consolidation practices including land merging, land leveling (LL), ditch construction (DC) and application of organic fertilizer (AO). A total of 10 paddy sites were selected under conventional tillage (CT) from non-land consolidation area as a control group in Y county, China. The results indicated that soil organic matter (OM), total nitrogen (TN), available phosphorus, bacterial functional diversity (BFD), bacterial and fungal abundances were significantly improved. Fields under LL, among all the land consolidation practices, might still face the risk of land degradation caused by low TN, OM and microbial diversity. High microbial biomass, BFD and OM were significantly higher in fields under AO in nutrient cycle. According to the results of comprehensive assessment, the samples with severe heavy metal contamination and low microbial diversity were generally concentrated in CT. These results indicated that land consolidation was an efficient technique to improve soil quality and could achieve higher quality of agricultural products.

The variation in microbial community structure under different heavy metal contamination levels in paddy soils.

As a global pollution problem, heavy metal contamination poses a serious hazard to soil microorganisms which play an extremely important role in soil chemical cycling and ecological persistence. However, the effects that different levels of heavy metal contamination in soils have on microorganisms and the interactions between them are still unclear. The purpose of this research is to analyze the microbial structure under different levels of heavy metal contamination, find out heavy metal tolerant species under different environmental conditions, then provide useful reference for the bioremediation of contaminated farmland. In this study, 16s rRNA high-throughput sequencing technology was used to investigate the microbial communities in severe level (SL), moderate level (ML), light level (LL) and clean level (CL) of heavy metal contaminated soils, and the relationships between environment variables and microorganisms were analyzed. The results showed that the concentrations of heavy metals and soil physicochemical properties had various impacts on microbial community composition under different heavy metal contamination levels. Most dominant bacteria were in significant negative correlation with Cd in ML region, and significantly correlated with TN and OM in LL region. However, there was no significant correlation between dominant fungi and the physicochemical properties in LL region. And most of the dominant fungi were significantly correlated with the heavy metal concentrations in SL region. The bacterial phyla such as Proteobacteria, Acidobacteria and Bacteroidetes showed more tolerance with heavy metal contamination in SL, ML and LL regions, respectively. Meanwhile, the dominant fungi of Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Zygomycota and Rozellomycota showed stronger correlations with heavy metal contamination in SL and LL regions. These results indicated that some microorganisms had strong tolerance to heavy metal contamination and had certain heavy metals digestion ability, which can create an appropriate soil environment for the growth of food crops.

Spatiotemporal evolution and driving factors of fertilizer reduction control in Zhejiang Province.

Facing the non-point source pollution caused by fertilizer loss, study on the agricultural factors that have an influence on fertilizer reduction could provide a basis for the implementation of policies on fertilizer reduction control. Based on the panel data during 2002-2016 with cumulative contribution model and Log-Mean Divisia Index (LMDI), this paper innovatively comes up with reduction driving functions (including agricultural scale, intensification, fertilizer utilization, and labor productivity), studies the cumulative contribution rate and driving factors of fertilizer reduction in county units of Zhejiang Province. Main conclusions are: (1) 37 of 63 county units (58.73%) showed decreased in fertilizer application; top five county units contributed 50+%; top county units that contribute to fertilizer reduction are in plain area in Northern Zhejiang, coastal area in Eastern and Southern Zhejiang, valley and basin area in Western and Southern Zhejiang where arable land is relatively even. (2) Fertilizer application intensity (fertilizer application per unit area of land cultivation) in Zhejiang Province increased by 18.67%, but there are only 15 county units where fertilizer application intensity is reduced. In general, fertilizer reduction in Zhejiang Province kept developing steadily. (3) Factors (fertilizer efficiency, intensification and agricultural scale) drive fertilizer reduction while labor productivity triggers the growth in application intensity. In Hangzhou, Ningbo and Shaoxing in Northern and Eastern Zhejiang, the above factors all have a prominent driving effect, but labor productivity also promotes fertilizer increment. In the end, this paper proposes policies on fertilizer reduction control in terms of efficiency, inputs and compensations.