Structure and functional heterogeneity of soil microbial communities in different farmland types on the Loess Plateau

Background,aim,and scope Soil microbes are important drivers of nutrient transformation and energy f low.Reclaiming forest land for agricultural use may have profound effects on soil properties and microbial communities.However,the response of soil microbial communities to soil reclamation in the dryland agroecosystem is less understood.Therefore,it is necessary to investigate the changes of soil microbial communities driven by land use conversion to promote nutrient cycling in reclaimed farmland.Materials and methods Based on the metagenomic technique,we evaluated the microbial composition and function of the newly created farmland(NF)after reclamation with two types of traditional farmland(slope farmland(SF),checkdam farmland(CF))on the Loess Plateau,and explored the response of nutrient cycling function to dominant genera and soil properties.Results The results showed that Proteobacteria,Actinobacteria,and Acidobacteria were prevalent in the three types of farmlands.Compared with SF and CF,NF increased the relative abundance of Actinobacteria and Nocardioides,as well as genes related to amino acid metabolism and carbohydrate metabolism.The relative abundance of functional genes related to carbon and nitrogen cycling in the NF was higher than that in the traditional farmland(SF and CF).The relative abundance of nutrient cycling functional genes was positively correlated with dominant genera in the three types of farmlands.Except for pH,soil physicochemical factors were negatively correlated with genes related to amino acid metabolism and carbon cycle.Discussion Previous studies have shown that the nutrient conditions of the soil may intensify the competition between the eutrophic and oligotrophic microbial populations.After long-term cultivation and fertilization,the soil properties of traditional farmland were significantly different from those of NF,leading to the differentiation of dominant microbial groups.Microbes usually have functional redundancy to cope with changing environments.Soil microbes in traditional farmland may contain more genes related to replication and repair,cell growth and death,and environmental adaptation in response to disturbances caused by agricultural practices.On the contrary,the NF was less disturbed by agricultural activities,and the soil properties were more similar to forest land,so the carbon and nitrogen cycle function genes were more abundant.The nutrient cycling function was affected by the abundance of microbial dominant groups and soil properties,which may be related to the availability of soil nutrients and agricultural disturbance in different farmlands.Aspects of soil microbial-driven nutrient cycling in agriculture could be regulated in sustainable method.Conclusions The change from forest land to farmland kept more carbon and nitrogen cycling function in the newly created farmland,while long-term agricultural activities have drastically changed the functional structure of traditional farmland,resulting in the nutrient cycling function more concentrated to meet the needs of crop growth.Recommendations and perspectives Hence,it is necessary to apply sustainable agricultural method to regulate microbial-driven nutrient cycling.The insights are meaningful for sustainable agricultural development and land management in arid areas.

Future Development Direction of the Restoration of Mountains,Rivers,Forests,Farmlands,Lakes,and Grasslands and the Faced Problems

In this paper,the definition,connotation,and internal relationship of mountains,rivers,forests,farmlands,lakes,and grasslands in China are elaborated,and the current situation of ecological restoration projects for mountains,rivers,forests,farmlands,lakes,and grasslands was introduced.Moreover,the problems that have arisen in the specific implementation process of pilot projects were analyzed,such as unclear target positioning,inaccurate analysis of ecological problems,insufficient engineering design systematicness,weak operability of evaluation standards,and weak coordination in engineering management.The development direction and major needs for the protection and restoration of mountains,rivers,forests,farmlands,lakes,and grasslands in the future have been proposed from four aspects:theoretical research,engineering design,effect evaluation,and monitoring and supervision.

Monitoring the hydrolyzation of aspirin during the dissolution testing for aspirin delayed-release tablets with a fiber-optic dissolution system

The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effects and affect the determination of dissolution rate assaying. In this study, the technique of differential spectra was employed, which made it possible to monitor the dissolution testing in situ. The results showed that the hydrolyzation of aspirin made the percentage of salicylic acid exceed the limit of free salicylic acid （4.0）, and the hydrolyzation may affect the quality detection of aspirin delayed-release tablets.

Dissolution behaviors of Ta_2O_5,Nb_2O_5 and their mixture in KOH and H_2O system

The dissolution behaviors of Ta2O5,Nb2O5 and their mixture in KOH and H2O system were investigated.A L9(34) orthogonal design was used to study the effects of reaction temperature,mass ratio of KOH to Ta2O5,and reaction time on the dissolution rate of tantalum.It was found that the effect of reaction temperature on the dissolution rate of tantalum was much greater than that of the other factors.The results of factorial experiments showed that Ta2O5 was mainly transformed into insoluble potassium tantalate at low temperature(350 ℃) and transformed into soluble potassium tantalate at high temperature(450 ℃).The insoluble potassium tantalate was analyzed by XRD,which was proved to be KTaO3.Differently,almost all Nb2O5 was transformed into soluble potassium niobate at 350-450℃.As for the mixture of Ta2O5 and Nb2O5,the dissolution rate of tantalum increased and the dissolution rate of niobium decreased as an interaction existed between niobium and tantalum.And increasing the mole ratio of Nb2O5 to Ta2O5 in the mixture was beneficial to the dissolution of both Ta2O5 and Nb2O5.In addition,the mechanism of the interaction between niobium and tantalum was also investigated through phase and chemical analysis.

The Dynamics and Driving Force of Farmland Ecosystem Productivity

Based on the experimental data of crop yield, soil water and fertility of a dryland farming ecosystem in northwest China, asystematic analysis is carried out to study the dynamics of dryland farming ecosystem productivity and its limitingfactors. This paper also discusses which of the two limiting factors, i.e., soil water or fertility, is the primary factor and theirdynamics. The result shows that fertility is the primary limiting factor when the productivity is rather low. As chemicalfertilizer input increases and the productivity promotes, water gradually becomes the primary limiting factor. Chemicalfertilizers and plastic film mulching are the two major driving forces that determine the crop productivity and its stabilityin these areas.

THE STRUCTURE AND DYNAMICS OF THE LAND RESOURCES SYSTEM IN THE FARMLAND SHELTER FOREST REGION IN THE NORTHEAST PLAIN

The structure and dynamics of land resources system in the shelter forest region in the Northeast Plain is discussed according to the remote sensing and statistical information from the typical profiles and spots. For agricultural utilization, the land resources system is made up of five components, i.e. man, land resources, water resources,climatic resources and barren land. The local economy depends heavily upon its land resources, especially farm land. Having been exploited for 50-60 years from the 1930s to 1980s, it has already changed from the reclaiming period into the declining period.There is no waste land to be reclaimed. Facing the increase of population and requirements and the decrease of farmland fertility, proper management of land resources is indispensable if local economic and living level is maintained. It is imperative to make artificial regeneration (highest input) for the land resources and to keep fine circle of thesystem. If only natural regeneration if relied, the system will be changed to vicious circle.

The Dissolution of the Cellulose in the N - ethylmorpholine - N - oxide (NMMO) - Water System with Hydrothermolysis

Tbe N - methylmorpholine - N - oxide (NMMO) - water solvent was used to dissolve the cellulose that was achieved by means of hydrothermolysis. Sample B, RS and WS used here were made from beech, rice straw and wheat straw respectively. They could be completely dissolved in the NMMO - water system. A commercial a - cellulose was employed in the comparative experiment. The entire dissolving process was Investigated. At a given temperature, the vacuum condition applied to the mixture of the cellulose and NMMO - water was very important in order to accelerate the dissolution of cellulose and shorten the dissolving period. After dissolution, degree of polymerization (DP) of all samples was measured by viscometry. Longer dissolving time and higher temperature could cause the degradation of the dissolved cellulose. N- propyl gallate could prevent the degradation of cellulose during the process of dissolution.

Effect of initial pH on chalcopyrite oxidation dissolution in the presence of extreme thermophile Acidianus manzaensis

The influence of initial pH on the chalcopyrite oxidation dissolution at 65 ℃ was investigated by bioleaching and cyclic voltammetiy experiments,and the oxidation products were investigated by XRD and Raman spectroscopy.Bioleaching results show that chalcopyrite dissolution rate increases with the decrease of the initial pH in chemical leaching,while the influence of initial pH on bioleaching is on the contrary.The presence of Acidianus manzaensis does not promote chalcopyrite dissolution under initial pH1.0,which mainly results from serious inhibition of high acidity to the growth of Acidianus manzaensis.Electrochemical experiments results show that anodic oxidation currents of electrolyte with or without Acidianus manzaensis both increase with the increase of initial pH,and covellite and sulfur are detected on the electrode surface.The results confirm that chalcopyrite dissolution in chemical leaching is under the combined action of oxidation and non-oxidation of proton,with conversion of chalcopyrite to covellite and elemental sulfur.

Research on the Species Diversity of Flower-visiting Syrphidae in the Farmland of Hanzhong Area

[Objective] The aim was to explore the species diversity of flower-visiting Syrphidae in the farmland of Hanzhong area.[Method] Based on the sample collection and the sorting and identification of collected specimens and literature,the species and their seasonal changes of flower-visiting Syrphidae in the agroecosystem of Hanzhong area were systematically analyzed.[Result] 5 015 specimens of Syrphidae were cheaked in this study,and 141 species of 53 genera of 16 families in three subfamilies of flower-visiting species of Syrphidae were identified in farmland of Hanzhong area,in which 65 species were Syrphinae;72 species were Milesiinae;while four species were Microdontinae.The species of Syrphidae in this region were active in April,May,June and July.There were two dominant species in this region,including Episyrphus balteatus and Eristalis tenax.[Conclusion] This study had provided theoretical basis for the studies on the flower-visiting habit and fecundation of insects of Syrphidae in this area.

The Innovation and Plights of Farmland Property Rights System Reform in Chongqing Municipality

Based on the background of national urban and rural comprehensive reform pilot area and the introduction of the profiles of research region and the data obtained by on-the-spot interview survey,the innovative models of farmland property rights system reform in Chongqing are introduced by applying participatory rural appraisal methods and examples. The innovative models cover buying shares of contract management rights,transforming from farmers to townspeople and mortgaging contract management rights. The plights exist in the reform are analyzed,among which the plights of buying shares of contract management rights are introduced from the following five aspects:the conflict with the present land contract laws,the possible new round of massive scale land loses,the confounded functions of government and enterprise caused by risk transference and the difficulties of handling assets when the contract management rights expired. Besides,the plights of the transforming from rural residents to urban residents are analyzed from four aspects,which include the particularity of reform,high financial pressure,emergence of interbedded people and difficulties of payoff of village-based companies. From the facets of limited mortgage area,risks of reimbursing the loan,legal risks of mortgage. The results show that the stock purchasing model of contractual management rights reveals the capital value of land and the model is of theoretical and practical significance in law and economics. However,the social security system is not perfect,so the stock purchasing model of contractual management rights can not be expanded. In addition,the participation of more famers and the expansion of enterprises are limited as well. The land comprehensive reform model of transforming from rural residents to urban residents is of positive significance to the comprehensive exploration of farmland property system reform,but this kind of model should be supported by strong economy. The stock purchasing model of contractual management rights is of significance to perfect the contractual management rights,but it conflicts with the existing laws and financial systems.

Characteristics of Nitrogen and Phosphorus Losses in Different Crop Rotation Systems in the North of Erhai Lake Basin

[Objective] Nitrogen and phosphorus losses of surface runoff in various crop rotation systems in the north of Erhai Lake basin were studied with the objective to provide references for risk evaluation of environmental pollution and formulating countermeasures to control the nonpoint source pollution from agriculture.[Method] Water samples collected in four typical crop rotation systems distributed in seven towns（townships） in the north of Erhai Lake basin were investigated,as well as the fertilizer input,to explore the dynamic change of nitrogen and phosphorus content in surface water of farmland and ditch water,and the correlation between fertilizer input and the concentrations of nitrogen and phosphorus in the surface water of farmland and in the ditch water.[Result] The results showed that nitrogen loss in surface water of farmland in different crop rotation systems differed greatly,and the risk of nitrogen loss was 38% lower in broad bean-rice crop rotation than that in garlic-rice crop rotation.The water soluble nitrogen was the primary form of nitrogen loss.The content of water soluble nitrogen was significantly higher in garlic-rice crop rotation than that in the other rotation systems,and the concentrations of nitrogen in the surface water of farmland in different crop rotation systems followed the sequence below：garlic-rice crop rotationryegrass-rice crop rotationbroad bean-rice crop rotationrape-rice crop rotation.The loss of phosphorus in the surface water of farmland was relatively low and phosphorus combined with silt was the primary form for phosphorus loss.There was no significant difference of the loss of various forms of phosphorus in different crop rotation systems.The contents of total nitrogen and total phosphorus in the surface water of farmland were higher than that in ditch water,with increasing rates of total nitrogen and total phosphorus in ditch water of 72% and 82%,respectively.Topdressing was the critical reason for the high concentrations of nitrogen and phosphorus in the surface water,which also caused the increasing load to the ditch water.[Conclusion] Both the nitrogen and phosphorus loss were the highest in garlic-rice crop rotation.Reasonable crop rotation systems should be established based on both the environmental and economic benefits.This study provided references for controlling the nonpoint source pollution of farmland and improving the water quality of Erhai Lake.

The dissolution of total suspended solids and treatment strategy of tailwater in a Litopenaeus vannamei recirculating aquaculture system

In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment during three periods of the aquaculture of the Litopenaeus vannamei:nursery(0–26 d),middle(27–57 d),and later(57–104 d).The variation of several water parameters during the dissolution of total suspended solid(TSS)in tailwater,applied with the effects of ozone on the microorganism and water quality parameters were investigated.Results showed that the TSS concentrations in tailwater decreased with time,although not significantly(P>0.05),whereas total ammonia nitrogen(TAN),nitrite(NO-2-N),and nitrate(NO_(3)^(-)-N)increased significantly(P<0.05).Therefore,TSS should be removed from the tailwater as early as possible,being most optimal within 4 h.Ozone removed 38.24%–48.95%of TSS,17.78%–90.14%of TAN,and 87.50%–98.90%of NO-2-N after 4 h of treatment.However,it resulted in the significant accumulation of NO_(3)^(-)-N.Moreover,the total number of Vibrio and bacterial counts in aquaculture tailwater was reduced completely by ozone within 4 h.Thus,these results provided technical details and data support for the effective treatment of tailwater from shrimp RAS.

The Application of MAPGIS in Basic Farmland Protection Plan Mapping

In this study,MAPGIS software was used in production of basic farmland protection plan maps based on the related practice of Jinkong town,Yanting County,Sichuan Province,China.It was proved that MAPGIS software could improve the efficiency of mapping greatly,and resolved technical problems in basic farmland protection plan mapping.

Construction of Legal System of China's Farmland Protection under the Coexistence of Multiple Objectives:Historical Logic,Practical Problems and Optimization Paths

[Objectives]To explore the evolution of the legal system of farmland protection and explore the rules and characteristics of policy development based on the theory and logic of institutional change since China's reform and opening up,reveal the problems and deep-seated reasons of its legislation,clarify the direction of farmland protection in the new period,and solve the"non-agricultural""non-grain"and ecological problems of farmland.[Methods]Literature analysis and inductive deduction methods were used.[Results]The evolution of the farmland protection legal system has gone through the process of"national consciousness-policy guidelines-institutional system",the change from"single subject to multiple subjects";change from the use of"one-way administrative means to coordinated use of administrative,economic and technical means".The practical problems of the farmland protection legal system are mainly due to the insufficient systematization of the farmland protection legal system itself,the generalization of quantity protection,the transformation of quality protection,and the absence of ecological protection.[Conclusions]It is recommended to improve the existing farmland protection legal system from the establishment of the Farmland Protection Law,the improvement of the farmland protection public participation mechanism and supervision mechanism,the establishment of the farmland quality construction and improvement system,the differentiated farmland occupation and supplementation balance system,and the ecological restoration system.

Extension Study on the Use of Slope Farmland in West Region

Based on the research of slope farmland in northern Shaanxi,the extension decision model was set up by the original theory of extenics. The optimal solution is obtained by expanding analysis,provide scientific basis for decision-making and increase the economic benefits to farmers.

Study on specifications of farmland shelterbelt net in Northeastern Plain of China

s: The farmland shelterbelts in Northeastern Plain of China have formed relatively complete net system. The func-tions of shelterbelt net in omnibearing wind check and prevention of frostbite as well as the field of integrated climate effect within shelterbelt net were analyzed, through located observation of meteorological factors. Within the shelterbelt net, the area with more than 10% efficiency of omnibearing wind check was determined as benefited area. The analysis of yield and quality of crops indicated that the sheltering range of shelterbelt net was 25 times tree height. The mature heights of the various varieties of poplar composed the shelterbelts were determined according to their height growth. Based on the comprehensive analysis above, the suitable size of farmland shelterbelt net in Northeastern Plain of China was decided to be 400 m×400 m.

Study on the Major and Trace Elements in Soil of Yunnan Farmland

In order to investigate the distribution of soil available micronutrients, and provide a theoretical basis for management of fertilizing reasonably on crops, the contents of major and trace elements （P, K, Ca, Mg, Cu, Fe, Zn, and Mn） in farm- land soil collected from Yunnan Province were determined by inductively coupled plasma-mass spectrometry （ICP-MS）, the contents and distribution of major and trace elements were also studied. The results showed that the contents of available P, K were balance, available Ca, Mg were deficient, and available Cu, Fe, Zn, Mn were very plentiful. Major and trace elements distribution of different landform areas were obviously different. The contents of trace elements （Fe, Zn and Mn） of central Yunnan Red Plateau were significantly higher than those of Hengduan Mountains in western Yunnan and those of karst plateau in eastern Yunnan. The contents of available P, K, and Ca gradually declined from west to east, while the content of available Cu rose gradually from west to east. The results are reference value to elements determination and agricultural production in farmland soils.

Heterointerface Engineering-Induced Oxygen Defects for the Manganese Dissolution Inhibition in Aqueous Zinc Ion Batteries

Manganese-based material is a prospective cathode material for aqueous zinc ion batteries(ZIBs)by virtue of its high theoretical capacity,high operating voltage,and low price.However,the manganese dissolution during the electrochemical reaction causes its electrochemical cycling stability to be undesirable.In this work,heterointerface engineering-induced oxygen defects are introduced into heterostructure MnO_(2)(δa-MnO_(2))by in situ electrochemical activation to inhibit manganese dissolution for aqueous zinc ion batteries.Meanwhile,the heterointerface between the disordered amorphous and the crystalline MnO_(2)ofδa-MnO_(2)is decisive for the formation of oxygen defects.And the experimental results indicate that the manganese dissolution ofδa-MnO_(2)is considerably inhibited during the charge/discharge cycle.Theoretical analysis indicates that the oxygen defect regulates the electronic and band structure and the Mn-O bonding state of the electrode material,thereby promoting electron transport kinetics as well as inhibiting Mn dissolution.Consequently,the capacity ofδa-MnO_(2)does not degrade after 100 cycles at a current density of 0.5 Ag^(-1)and also 91%capacity retention after 500cycles at 1 Ag^(-1).This study provides a promising insight into the development of high-performance manganese-based cathode materials through a facile and low-cost strategy.

The Scale of Constructing Mountainous Cities in Yunnan Province based on “Benchmark” Farmlands

In 2011, Yunnan provincial committee and government proposed the strat- egy of constructing mountainous cities in order to protect farmlands and guarantee crop safety, which makes full use of hills and gentle-slopes and transforms land use pattern. However, social and economic development performs unevenly in Yun- nan, supplemented by varied geographical conditions, so that constructing mountain- ous cities should proceed as per local conditions. The research proposed the con- trol of constructing mountainous cities provided crop safety under the principle of farmland protection and measured the quantities of demanded construction lands ac- cording to science of population prediction and ekistics, based on which the control scales of constructing mountainous cities were determined by multiplying basic farm- land coefficient and the area of newly increased construction lands. The research is of significance for guiding the construction of mountainous cities and avoiding the occupation of construction lands on farmlands.

Temperature-dependent solubility of Rebaudioside A in methanol/ethanol and ethyl acetate mixtures:Experimental measurements and thermodynamic modeling

The equilibrium solubility of Rebaudioside A(Reb A)FormⅡin binary mixtures of methanol/ethanol and ethyl acetate was quantitatively determined within the temperature range of 283.15—328.15 K at ambient pressure.The experimental findings indicate a positive correlation between the solubility of Reb A(FormⅡ)and both the temperature and the methanol/ethanol content in the solvent system.To describe the solubility data,six distinct models were employed:the modified Apelblat equation,theλh model,the combined nearly ideal binary solvent/Redlich—Kister(CNIBS/R—K)model,the van't HoffJouyban-Acree(VJA)model,the Apelblat-Jouyban-Acree(AJA)model,and the non-random two-liquid(NRTL)model.The combined nearly ideal binary solvent/Redlich—Kister model exhibited the most precise fit for solubility in methanol+ethyl acetate mixtures,reflected by an average relative deviation(ARD)of 0.0011 and a root mean square deviation(RMSD)of 12×10^(-7).Conversely,for ethanol+ethyl acetate mixtures,the modified Apelblat equation provided a superior correlation(ARD=0.0014,RMSD=4×10^(-7)).Furthermore,thermodynamic parameters associated with the dissolution of Reb A(FormⅡ),including enthalpy,entropy,and the Gibbs energy change,were inferred from the data.The findings underscore that the dissolution process is predominantly endothermic across the solvent systems examined.Notably,the entropy changes appear to have a significant influence on the Gibbs free energy associated with the dissolution of Reb A(FormⅡ),suggesting that entropic factors may play a pivotal role in the studied systems.