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.

Sex Pheromone Components of the Female Black Cutworm Moth in China: Identification and Field Trials

The sex pheromone blend of a China strain of the black cutworm moth Agrotis ypsilon （Rottemberg） （Lepidoptera： Noctuidae） was investigated. Chemical analysis of pheromone gland extracts of 3-day-old females showed that individual isolated glands contained only very small amounts of pheromone. The high-resolution gas chromatography combined with mass spectrometry （GC-MS） analysis showed the presence of Cis-7-dodecenyl acetate （Z7-12：Ac, A）, Cis-9-tetradecenyl acetate （Z9-14：Ac, B）, Cis- 11-hexadecenyl acetate （Z 11 - 16 ：Ac, C）, Cis-8-dodecenyl acetate （Z8-12：Ac, E） and Cis-5-decenyl acetate （Z5-10：Ac, D） in biologically active pheromone gland extracts. An extract of one gland from a day 3 female gave the following values for the gland components： 0.245±0.098ng for Z7-12：Ac, 0.080±0.031ng for Z9-14：Ac, 0.089±0.033ng for Z11-16：Ac, 0.085±0.031ng for Z5-10：Ac, 0.105±0.065ng for Z8-12：Ac per female. The percentages of Z7-12：Ac, Z9-14：Ac, Z11-16：Ac, Z5-10：Ac and ZS-12：Ac in pheromone gland extracts from individual females were （meaniSE） 40.451±13.66, 13.176±5.279, 14.943±5.142, 14.392±6.10 and 17.225±9.792 respectively, and the percentages of Z7-12：Ac, Z9-14：Ac and Z11-16：Ac were 58.75±9.429, 18.91±7.539 and 22.34±7.209. Field trials indicated that each single component of sex pheromone was non-effective and captured no males. The lures baited with duality compound of AB （3 ： 1） had a certain attraction to males, the mean captured number was 2.6. The attraction ability of the lures baited with ternary compound of ABC （3 ： 1 ：1） to males added significantly, the mean captured number per trap was 7.40, which was 2.8 times of duality compound of AB （3 ： 1）. The contents of sex pheromone could obviously affect its capture ability to males, the mean captured number was the highest at the dosage of 200 μg.

Effects of Different Nutrient Management Systems and Cultivation Methods on Crop Yield and Soil Fertility

[Objective] The aim was to provide scientific basis for improving the middle and low yielding fields fertility and farmland productivity. [Method] A field experiment was carried out to study the effects of different management practices （including nutrient management systems and cultivation methods） on crop yield and soil fertility in winter wheat/summer maize rotation system. [Result] The crop yield in the treatment of the high yield and high efficiency system was remarkably higher than farmer conventional management practice. After five crop seasons experiment, the contents of soil organic matter for high yield and high efficiency system increased 2.72-3.01 g/kg, and that of soil total nitrogen increased 0.12-0.16 g/kg, the soil Olsen-P increased 5.2 mg/kg and the soil available K （NH4OAC-K） increased about 37.8 mg/kg. [Conclusion] Considering the yield and soil fertility comprehensively, the management system of high yield and high efficiency could effectively increase the crop yield and improve the soil fertility.

Distribution of Nutrients in Arable Land Soil of Western Hainan

[Objective] This study aimed to reveal distribution characteristics of soil nutrients in tropical farmland, thereby providing a reference for cropland management and balanced fertilization in the tropical area. [Method] Combining field survey and laboratory analysis, distribution status of nutrients in arable land of Baisha Li Autonomous County of Hainan Province was investigated. [Result] The soil in Baisha Li Autonomous County was acidic in overall with average pH value of 5.0. it had medium organic matter level （average of 19.3 g/kg） and rich alkali-hydrolyzable nitrogen content, but was lack of available phosphorus and available potassium. The spatial distribution of available nitrogen, available phosphorus and available potassi- um in the soil was uneven. The spatial distribution of soil nutrients was mainly related to soil parent materials of the investigated area and pH value of the investigated soil. [Conclusion] According to the distribution characteristics of nutrients in the soil, awareness of land use and land maintenance should be strengthened, application amount of organic fertilizers should be increased, chemical fertilizers should be applied rationally, and fertilization structure should be optimized in the future.

Isolation,Screening and Identification of Cellulose Decomposing Strains in Straw-amended Soil

[Objective]The aim was to isolate cellulose decomposing strains with high activity from straw-amended soil.[Method]Screening of CMC solid culture and shaking culture rescreening were carried out to obtain cellulose decomposing strains with high activity from the corn straw amended soil,which were analyzed by 16rDNA sequence analysis.[Result]A bacterium and a fungus with higher endonucleases activity were obtained through preliminary screening and secondary screening,a fungus with higher filter paper enzyme activity,and a bacterium（NO.5 strain） with higher of both filter paper enzyme activity and CMC enzyme activity were obtained.The result of 16S rDNA sequence analysis showed that the similarity was 100% between NO.5 strain and Bacillus subtilis.[Conclusion]NO.5 strain was identified as Bacillus subtilis.

Spatial-Temporal Distribution Characteristics and Limiting Factors of Medium-low Yield Farmland in Tianjin

[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [Method] Based on the statistical date of Tianjin and its relevant counties and districts, the yield standard was set up to classify high-yield, medium-yield and low-yield farmland in Tianjin. The author analyzed area change of medium-low yield farmland in six agricultural counties and districts （including Jixian County, Wuqing District, Baodi District, Ninghe County, Jinghai County and Dagang district of Binghai New Area） from 1980 to 2010. [Result] The results showed that the average yield of grain rose from 2 445 kg/hm^2 in 1980 to 5 130 kg/hm^2 in 2010, increasing 109.82%. The area of mediumlow yield farmland was reduced from 291 250.13 hm^2 in 1985 to 76 489.87 hm^2 in 2010, coming down 74%. In Tianjin, the area of medium-low yield farmland of 2010 accounted for 19% of the total farmland, of which the ratios of medium-low yield farmland of Jinghai County, Jixian County, Dagang district of Binghai New Area, Wuqing District, Baodi District and Ninghe County were 43.12%, 18.59%, 17.23%, 14.01%, 7.05% and 0, respectively. Low soil nutrient content, drought and water shortage, as well as soil salinization were the main yield limiting factors to mediumlow yield farmland in Tianjin in 2010. [Conclusion] The countermeasures to improve the medium-low yield farmland were proposed, involving enhancing the investment of the government, strengthening the construction of water conservancy infrastructure, further improving the soil fertility, as well as saline and alkaline land, optimizing the farming system and planting drought and salt tolerance crops, etc.

Path Analysis on the Meteorological Factors Impacting Soil Respiration Rate of Wheat Field

[Objective]The experiment aimed to study the effects of meteorological factors under different weather conditions on soil respiration. [ Method] The path analysis was used to analyze meteorological factors which influenced soil respiration of wheat field under different weather condition and at jointing stage. [ Result] In sunny day, the correlations between ground temperature at 5 cm, solar radiation, air relative humidity, air temperature and soil respiration were all at significant level while solar radiation and ground temperature at 5 cm were the major factors which influenced soil respiration. In cloudy day, solar radiation was a major factor which influenced soil respiration.[ Conclusion] The soil respiration and surplus path coefficient in sunny day were all higher than these in cloudy day, which demonstrated that except influenced by ground temperature, air temperature, solar radiation and air relative humidity, the soil respiration was also influenced by other factors especially biological factor.

Effects of Ploughing Astragalus sinicus at Maturity Stage on Rice Yield and Soil Properties of Paddy Field

[Objective] The effects of ploughing Astragalus sinicus at maturity stage as green manure on paddy soil properties were studied to provide references for ad- vancing the green manure production and field sustainable development. [Methods] A three-year field positioning experiment was carried out. In the first year, five differ- ent levels （0, 2.81, 5.61, 8.42, 11.23 t/hm~） of Astragalus sinicus ploughed at matu- rity stage were designed. And in the next two years, the amounts of ploughed As- tragalus sinicus at maturity stage were based on the natural growth amounts of As- tragalus sinicus at maturity stage of the former year in each plot field. The yields of Astragalus sinicus at maturity stage were estimated and ploughed directly before rice transplanting. Rice yield, soil nutrients, biological properties and water-stable aggre- gates of paddy fields were measured as well. [Results] The effective panicles and rice yields increased significantly after ploughing Astragalus sinicus at maturity stage. Meanwhile, the organic acid content in paddy field increased and the activities of soil phosphatases, invertase and catalase were higher. The soil dissolved organic carbon also increased with the increasing application of green manure. However, excess amount of green manure inhibited the soil microbial biomass carbon content. The macro aggregates and micro aggregates gathered to middle aggregates. [Conclusion] As green manure, the use of Astragalus sinicus at maturity stage could improve soil physiochemical and biological properties, improve soil fertility and increase rice yield significantly. But the ploughing amount of Astragalus sinicus at maturity stage before rice transplanting should be less than 8.42 t/hm2 （dry weight.

Optimization of micro milling electrical discharge machining of Inconel 718 by Grey-Taguchi method

The optimization of micro milling electrical discharge machining（EDM） process parameters of Inconel 718 alloy to achieve multiple performance characteristics such as low electrode wear,high material removal rate and low working gap was investigated by the Grey-Taguchi method.The influences of peak current,pulse on-time,pulse off-time and spark gap on electrode wear（EW）,material removal rate（MRR） and working gap（WG） in the micro milling electrical discharge machining of Inconel 718 were analyzed.The experimental results show that the electrode wear decreases from 5.6×10-9 to 5.2×10-9 mm3/min,the material removal rate increases from 0.47×10-8 to 1.68×10-8 mm3/min,and the working gap decreases from 1.27 to 1.19 μm under optimal micro milling electrical discharge machining process parameters.Hence,it is clearly shown that multiple performance characteristics can be improved by using the Grey-Taguchi method.

Basic Farmland Plan Based on Farmland Gradation

Taking B District in A City as an example, quality classification of basic farmland was evaluated based on farmland gradation. It can be concluded from the analysis that utilization grade of basic farmland in current round was 16.82 without consideration of farmland gradation updating, and the grade enhanced by 0.08, still lower by 0.11 than that in last round, when the updating was taken into account. Finally, the reasons for problems occurred in the round were analyzed as follows： less consideration of protection on basic farmland in orientation of urban development; neglecting of basic farmland quality in Overall Plan of Land Utilization; non-classification of excellent lands after land consolidation; untimely updating of farmland gradation. In addition, the countermeasures were proposed correpondingly, including strengthening of basic farmland quality in the Plan, classification of excellent lands after consolidation, timely updating and inclusion of farmland gradation into ＂one map＂ project.

Effects of Straw Covering and Different Types of Potassium Fertilizer on Salinity Accumulation in Surface Layer of Tobacco-planted Paddy Soil

[Objective] This study aimed to investigation the effects of straw covering and different types of potassium fertilizer on salinity accumulation in surface layer of tobacco-planted paddy soil in southern China. [Method] Tobacco variety ‘Yunyan87’ was used as the experimental material to investigate the effects of salinity accumulation in surface layer of tobacco-planted paddy soil on the growth and development of flue-cured tobacco using different types of potassium fertilizer and mulching cultivation methods. [Result] The results showed that K＋ , Ca2＋ , SO42and NO3-were the major salt ions in topsoil at different growth stages of flue-cured tobacco, Na ＋ and Mg2＋ contents were also relatively high at vigorous growth stage, indicating that these salt ions were easily accumulated in surface layer of soil; to be specific, the absolute increase of salt ion concentration showed a decreasing order of K＋ SO42- NO3-Ca2＋ Mg2＋ Na＋ Cl-, while the relative increase of salt ion concentration showed a decreasing order of Ca2＋ K＋ Na＋ NO3-SO42-Mg2＋ Cl-. At 60 d posttransplanting, total salt content in topsoil reached the minimum of 359.1 mg/kg in Treatment 2, total salt content in topsoil reached the maximum of 536.1 mg/kg in Treatment 5 （CK）, which was significantly higher than that in other treatments. At 90 d post-transplanting, no significant difference was observed in total salt content among various treatments. At harvesting period, total salt content in topsoil reached the maximum of 3 278.4 mg/kg in Treatment 1, which was significantly higher than that in other treatments. Topsoil pH showed no significant differences among various treatments at three different periods, ranging from 5.39 to 5.59. Straw covering could effectively reduce salt content in topsoil, accelerate vigorous growth of tobacco, shorten vigorous growth period and increase plant height, leaf number and lead area; at vigorous growth stage, root vitality and root volume of tobacco were improved, but the yield and output value were relatively low. Major agronomic traits and yield of tobacco showed no significant difference among various treatments. Output value of tobacco reached the maximum of 24 196.8 yuan/hm2 in Treatment 3, which was significantly higher than that in other treatments. [Conclusion] Appropriate types and proportions of potassium fertilizer and straw covering can effectively reduce the total salt content in tobacco-planted paddy soil and increase the effective supply amount of K＋ , Ca2＋ , SO42-and NO3-, thereby promoting and improving the root vitality of tobacco, which is conducive to the growth and development of tobacco and will eventually enhance the yield, quality and economic benefits of flue-cured tobacco.

Nutrient Content in Soils and Adaptability of Corn in Yuanzhou District,Guyuan City

[Objective] The aim was to research rational fertilization of corn in Yuanzhou District, Guyuan, Ningxia Hui Autonomous Region. [Method] Nutrient con- tents in soils in Yuanzhou District were measured with conventional analysis method and the suitable fertilization scheme of corn growth was proposed based on fertiliz- er-application rule of corn growth and nutrient balance. [Result] Soil in farmlands in Yuanzhou District was of alkalinity; organic matter, N, P and Zn were shortage; S was extremely insufficient; Fe and Mn were moderate; K was abundant; Cu would satisfy crop growth, [Conclusion] The research provides references for yield increase, reduction of chemical fertilizer and related pollution for corn growth.

Prevention and control of coalfield fire technology:A case study in the Antaibao Open Pit Mine goaf burning area,China

It is very difficult to clearly detect the location of a burning area in a coal mine since it is hidden underground.So we conducted research on the distribution of the burning area before controlling it.Firstly,the original drilling technique was used to analyze and determine the loose and scope of caving of burning area through field test,and then obtained the gases and the temperature data in this area were according to the borehole data.By analyzing these data,we found out that the location of burning area concentrated in the loose and caving area;and finally,the location and development of the burning area within the tested area were accurately determined.Based on this theory,we used the ground penetrating radar(GPR) to find out the loose and caving scale in the burning area during the control process of the burning area,and then located the fire-extinguishing boreholes within target which we used to control burning fire in the section.A mobile comprehensive fire prevention and extinguishing system based on the three-phase foam fire prevention and control technique was then adopted and conducted in the burning area which took only 9 months to extinguish the 227,000 m 2 of burning area of 9# coal.This control technology and experience will provide a very important reference to the control of other coalfield fire and hillock fire in the future.

Morphological analysis of the Chinese Cipangopaludina species(Gastropoda; Caenogastropoda: Viviparidae)

Viviparidae are widely distributed around the globe, but there are considerable gaps in the taxonomic record. To date, 18 species of the viviparid genus Cipangopaludina have been recorded in China, but there is substantial disagreement on the validity of this taxonomy. In this study, we described the shell and internal traits of these species to better discuss the validity of related species. We found that C. ampulliformis is synonym of C. lecythis, and C. wingatei is synonym of C. chinensis, while C. ampullacea and C. fluminalis are subspecies of C. lecythis and C. chinensis, respectively. C. dianchiensis should be paled in the genus Margarya, while C. menglaensis and C. yunnanensis belong to genus Mekongia. Totally, this leaves 11 species and 2 subspecies recorded in China. Based on whether these specimens' spiral whorl depth was longer than aperture depth, these species or subspecies can be further divided into two groups, viz. chinensis group and cathayensis group, which can be determined from one another via the ratio of spiral depth and aperture depth, vas deferens and number of secondary branches of vas deferens. Additionally, Principal Component Analysis indicated that body whorl depth, shell width, aperture width and aperture length were main variables during species of Cipangopaludina. A key to all valid Chinese Cipangopaludina species were given.

Analysis of Comprehensive Benefits of Transforming Slope Farmland to Terraces on the Loess Plateau:A Case Study of the Yangou Watershed in Northern Shaanxi Province,China

De-farming slope farmland has been an effective measure in recent years to improve environment and prevent soil and water loss on the Loess Plateau.There are different views about the defarming method,and also various de-farming patterns have been put into practice.This paper takes the Yangou Watershed in Shaanxi Province of China as a case for studying the comprehensive benefits of transforming slope farmland to terraces.Based on the day-by-day meteorological data of the Yan'an station in 2005 and the data of terrain features,soil and land use data of the Yangou Watershed,the impact of transforming slope farmland on terraces were simulated and analyzed in aspects of yield increase and water-soil conservation under different topographic conditions with the aid of software WIN-YIELD.Furthermore,an empirical analysis was applied to study the effects of transforming slope farmland to terraces in the Yangou Watershed.The results show that:(1) The bigger the topographic gradient is,the more remarkable benefits it has in yield increase and water-soil conservation.(2) Farmland with slope below 5° could be retained,but farmland with slope above 15° should be converted to forest or grassland as soon as possible.(3) Transforming slope farmland to terraces has the same remarkable effects as the current policy of "Relieving and de-farming" in improving agricultural production conditions,safeguarding food security,raising permanent vegetation coverage rate,and preventing soil and water loss.Besides,it is more cost-effective than the policy of "Relieving and de-farming".It's strongly suggested that the policy of transforming slope farmland to terraces be carried out on the Loess Plateau without delay.

Effects of Tillage and Mulch Methods on Soil Moisture inWheat Fields of Loess Plateau, China

Effects of different methods of tillage and mulch on soil moisture at fallow stage were studied in rainy andrain-deficient years. Soil moisture content per 20 cm was measured vertically within 0-300 cm soil layers in anexperiment with five treatments: deep-loosening tillage (DLT), traditional tillage (TT), plastic mulch (PM),straw mulch (SM) and plastic plus straw mulch (PSM). All mulch treatments were under no tillage conditions.Total storage of precipitation in soil from 0 to 300 cm was determined before sowing. Results showed thatthe new methods of tillage and mulch were the basic ways to improve water condition in dryland wheat fields.In a rainy year, PM with no tillage played a significant role in storing and conserving precipitation, while ina rain-deficient year, the role was not significant. Due to evaporation, DLT did not promote the storage ofsoil moisture. SM was the best way to store and conserve soil moisture. In SM treatment the wheat yieldsincreased by more than 20%.

Properties of L-band differential InSAR for monitoring mining-induced subsidence in coalfield of Jining, Northern China

The properties and feasibility of L-band differential InSAR for detecting and monitoring mining-induced subsidence were systematically analyzed and demonstrated. The largest monitored subsidence gradient of 7.9×10-3 and magnitude of 91 cm were firstly derived by theoretical derivation. Then, the stronger phase maintaining capacity and weaker sensitivity to minor land subsidence compared with C-band DInSAR were illustrated by phase simulation of the actual mine subsidence. Finally, the data processing procedure of two-pass DInSAR was further refined to accurately observe subsidence of a coalfield of Jining in Northern China using 7 ALOS PALSAR images. The largest monitored subsidence magnitude of 39.22 cm and other properties were better investigated by testing results interpretation and subsidence analysis, and the absolute difference varying from 0.5 mm to 17.9 mm was obtained by comparison with leveling-measured subsidence. All of results show that L-band DInSAR technique can investigate the location, amount, area and other detailed subsidence information with relatively higher accuracy.

Pollen and Phytolith Analyses of Ancient Paddy Fields at Chuodun Site, the Yangtze River Delta

A number of paddy fields pertaining to the Majiabang Cultures (5500-3800 years BC) were discovered during the archaeological excavations that were carried out since 1998 at the Chuodun site in the Yangtze River Delta. The pollen and phytolith analyses of two soil profiles from the northeastern part of this site were carried out to trace the agricultural practices of the Neolithic period. The phytolith results showed that rice domestication in the Yangtze River Delta could be traced back to as early as the Majiabang Culture. The pollen assemblage also revealed low levels of aquatic species, similar to that in modern paddy fields. This finding suggested that humans might have removed weeds for rice cultivation during the Neolithic period. Thus, pollen analysis in association with phytolith analysis was a promising method for identifying ancient paddy fields.

Parametric optimization and microstructural characterization of friction welded aeronautic aluminum alloy 2024

Continuous drive friction welding was employed to join the aeronautic aluminum alloy 2024.Parametric optimization and microstructural characterization were investigated.Results show that friction pressure is the most significant factor influencing the tensile strength of joints.To obtain a high joint efficiency,the combination of moderate friction pressure,less friction time and higher upset pressure is recommended.The optimized joint efficiency from Taguchi analysis reaches 92% of base metal.Under the optimized experimental condition,the interfacial peak temperature is calculated analytically in the range of 779-794 K,which is validated by experimental data.Fine recrystallized grains caused by the high temperature and plastic deformation are observed in the friction interface zone.The grain refinement is limited in the thermo-mechanically affected zone,where most of matrix grains are deformed severely.The extensive dissolution and limited re-precipitation of strengthening phases result in a lower microhardness in the friction interface zone than that in the thermo-mechanically affected zone.