Abstract:Surface roughness of farmland, as a result of the joint effects of land management and soil erosion, has a critical impact on the processes of surface runoff and soil erosion. Through simulated rainfall experiments, investigation was made of effect of soil surface roughness on rainfall erosion as affected by slope position on a loess slope, using high-precision 3-D laser scanning techniques. Results show that of the same slope, the top, side and foot was significantly different in statistical characteristics of elevation and the effect of soil surface roughness on rainfall erosion was significantly affected by slope position. Soil surface roughness was found to be in significant linear relationship to gradients of micro-slopes. It is, therefore, concluded that the effect of surface roughness on rainfall erosion varies spatially.

Abstract:To study characteristics of the disintegration of purple parent rocks of the Matoushan group (K₂m), the Lufeng group (J₁l) and the Tuodian group (J₃t) as affected by water environment (soaking in water or wetting the surface), heat environment (natural diurnal temperature difference or extreme temperature difference), and their interaction, an experiment, designed to have five treatments, i.e. wetting and extreme temperature difference (WETD), socking and extreme temperature difference (SETD), soaking and natural diurnal temperature difference (SNTD), wetting and natural temperature difference（WNTD） and extreme temperature difference (ETD), were carried out. Results show that the five treatments followed the order of WETD > SETD > SNTD > WNTD and ETD in terms of rock integration rate, which suggests that in the case of big temperature difference, the parent rocks are more likely to disintegrate when getting wet and dry alternately than when being soaked all the time, while in the case of small temperature difference, it is the other way round. The factor of temperature alone does not have much effect on disintegration of the parent rocks. In terms of mean disintegration rate, the 3 parent rocks follow the order of J₃t﹥J₁l﹥K₂m, which is closely related to their chemical constitution, mineral compositions and microstructures. The experiment shows that disintegration rate has a good positive linear relationship with temperature variation, moisture alteration and/or number of treatment cycles in all the rocks except for J3t, of which the integration rate is negatively correlated with the number of treatment cycles.

Abstract:The Sunjiacha Basin of Lanzhou, Gasu Province was cited as a case for study. Geostatistic analysis was done of the data of soil moisture measured in that region during 1982, 1983 and 2011 for vertical variability of the soil moisture. Results show that the spherical model fits very well the vertical distribution of soil moisture in all the lands different in land-use (terrace field, waste slope, slope farmland and woodland) in wet years, quite well only in terrace field and woodland and not in slope farmland and waste slope in normal years, and still to some extent in terrace field and woodland in dry years. Soil moisture in slope farmland and waste slope varies randomly in distribution, and even if in the rainy season its spatial autocorrelation is also very weak. The vertical variations of soil moisture in all the lands and in all the years demonstrate a significant seasonal trend and go within the range of 1.687 ~ 3.404 m, which tallies basically with the extend of variation of the soil properties measured in the range self-similarity.

Abstract:Based on the data obtained through manual observation and automatic observation during the period when all the basic meteorological stations in China monitored soil temperature using the two observation methods simultaneously, analyses were made of differences between soil temperatures obtained through different observation methods in various soil layers. Results show that the difference between manual observation and automatic observation in daily mean soil temperature was no more than 0.11℃ and decreased with increasing soil depth. In the soil layer of 5 cm ~ 320 cm, whether in winter or in summer, the mean difference was ±0.2℃ in most parts of China. Standard deviation of the daily mean difference in soil temperature between the two methods declined from 0.78℃ in the shallow soil layers to 0.47℃ in the deep soil layers, with uncertainty exceeding 1℃ in soil layers (5 cm ~ 20 cm), but lingering below 1℃ in soil layers (40 cm ~ 320 cm). As a matter of fact, no significant difference in daily mean of soil temperatures was found between automatic observation and manual observation in all the observation stations, except a few. The differences observed were attributed to inhomogenous distribution of the horizontal temperature field and sharp vertical temperature gradient in the soil and asynchronous operation of the two methods.

Abstract:No matter whether a farmland ecosystem acts as source or sink of global greenhouse gases, it has an important impact on annual variation of the concentration of carbon dioxide in the atmosphere. In this study, four counties, namely Minhou, Pucheng, Tongan and Yongding, located in different geographical locations in Fujian Province, subtropical China, were selected as typical study zones. Based on the data of field measurements at 23 869 sampling site in 1982 and 12 521 sampling sites in 2008, scattered in these four counties, a 1:50 000 database of soil type-land use pattern was established, analysis was carried out of changes in organic carbon density in the farmlands of Fujian in the past 30 years as affected by group, sub-group, genus and land use of the soils, and estimation was done of the soil organic carbon storages in the farmlands of the province in these two historical periods, using the scaling up method. Results show that the farmlands in Fujian as a whole acted as a weak carbon sink in the past 30 years, with carbon density and carbon storage increased by C 0.24 kg m^-2 and 4.26 Tg, respectively. Contribution of the farmland ecosystems to the “carbon sink/source” varied sharply with soil type and landuse pattern. When speaking of soil types, purplish soil, acid purplish soil and calcic mud field contributed the greatest to the “carbon sink” in soil group, soil subgroup and soil genu, respectively, with organic carbon density increased by C 0.63, 0.63 and 1.25 kg m^-2, respectively; while coastal solonchaks, coastal solonchaks and yellow sandy soil were the major contributors to the “carbon source” in soil group, soil subgroup and soil genu, respectively, with organic carbon density decreased by C 0.59, 0.59 and 1.08 kg m^-2, respectively. In terms of land use, irrigated paddy fields were the major carbon sink in the province with organic carbon density increased by C 0.27 kg m^-2; while irrigated uplands the main carbon source with organic carbon density decreased by C 0.36 kg m^-2. The findings suggest that in formulating policies for management of soil organic carbon in farmlands of Fujian in the years to come, priority should be given to effective management measures for the types of soils and the patterns of land use that are large in area and cause organic carbon density to decrease.

Abstract:In the field of a long-term experiment on integrated water and nitrogen management in the Fengqiu National Agro-ecological Experiment Station, soils samples were collected from plots subjected to different nitrogen fertilization rates (NR), i.e. 0, 150, 190, 230 and 270 kg hm^-2 per season, separately for analysis of parameters of soil fertility (i.e. soil pH, total N, total P, total K, alkalytic N, available P, available K and organic C). Results show that nitrogen fertilization decreased soil pH, available P and total K, but increased total N, alkalytic N and organic C to a varying degree. Apart from organic C which gradually increased with the increase in NR, no other parameters demonstrated any regular changes with increasing NR. After being subjected to 0, 3, 6 and 10 cycles of drying-wetting alternation and 60 days of incubation, soil samples were analyzed for chemical and biological properties (i.e. ammonium N, nitrate N, dissolved organic C, urease activity, dehydrogenase activity, microbial biomass C and basal soil respiration). Two-way ANOVA demonstrates that the number of drying-wetting cycles (NDW) considerably (p< 0.001) affected ammonium N, nitrate N, inorganic N, dissolved organic carbon, dehydrogenase activity, microbial biomass C and basal soil respiration, and that NR and NDW had no significant interactive effects on soil properties, except for dehydrogenase activity. Irrespective of NR, nitrate N, inorganic N, dissolved organic C, urease activity, dehydrogenase activity and microbial biomass C increased with NDW, while BSR responded reversely. Soil properties variation coefficients in soils under high-rated nitrogen fertilization (> 190 kg hm^-2) were lower, and easier to get cluster. The above findings demonstrate that in soils subjected to drying-wetting alternation, high-rated nitrogen fertilization may help maintain their biochemical stability.

Abstract:Heavy metal pollution of soils is an issue that has aroused high concerns among scientists the world over, and it is the premise of establishing related regulatory measures to specify trend of the spatio-temporal variation of heavy metal content in the soil. A case study was performed of Fengqiu County of Henan Province, a fluvo-aquic soil area typical of the Huang-Huai-Hai Plain, based on statistical analysis and geostatistical spatial interpolation of GIS data. The study was aimed at specifying current contents of soil heavy metals (Cr, Hg, As, Cu, and Zn) and their variation trends in the past years; determining areas and spatial distributions of the soils up separately to various standards for soil heavy metals, such as the natural background values, Criteria of Grade I of the National Standard for Soil Environmental Quality and the Standard of Soil Environmental Quality for Green Food Production; and eventually based on the two preceding researches quantitatively evaluating comprehensive soil heavy metal environment quality of the soils up to the criteria of Grade I of the National Standard with the Nemerow integrated pollution index method and their distributions within the county. Results show that the average contents of the five heavy metals, except Hg of which the average content was nearly on the same level as the background value, were slightly higher than the background values, but far below the Criteria of Grade I. And all the five heavy metals, except As, showed an increasing trend in content with the years passing by. The county had over 98% of its area of soils exceeding the criteria of Grade I of the National Standard in content of Cr, As and Zn, 100% in content of Hg, and over 91% in content of Cu, and over 99% beyond the Standard of Soil Environmental Quality for Green Food Production. Based on the criteria of Grade I, analysis with the Nemerow integrated pollution index method revealed that the soils of Fengqiu were good in comprehensive soil environmental quality, except for less than 3% slightly polluted, which means that the soils in Fengqiu are suitable to cultivation of all kinds crops in view of the current condition of soil heavy metal pollution. However, in some individual localities where the soils are beyond the standard for green food production, special attention should be paid to timely preventive measures for the issue of heavy metals pollution.

Abstract:To study spatial variability of soil heavy metals may help reveal effects of human activities on soil heavy metals accumulation and provide important basic data for soil utilization and its pollution risk assessment. Based on systematical analysis of heavy metals, arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), zinc (Zn) in the environmental media, such as soil, irrigation water, fertilizer, and plants of a greenhouse vegetable production system typical of the suburbs of Nanjing, spatial variability and accumulation of heavy metals in the soil was explored causes of the accumulation analyzed, and effect of the accumulation on plant uptake of heavy metals in this system discussed. Results show that (1) accumulation of Cu, Hg, Pb, and Zn in the soil was significant compared with that in open fields, and the average contents of Cu, Hg, and Pb in the soil were higher than the criteria set in the Environmental Quality Evaluation Standard for Farmland in Greenhouse Vegetable Production; (2) Large amounts of agro-inputs significantly affected spatial variability of soil properties, and hence, the spatial variability of soil Cu, Hg, Pb, and Zn in a similar way, for these elements were closely correlated with soil properties; and (3) The changes in soil properties and the accumulation of heavy metals strongly affected leaf vegetable’s uptake of heavy metals, and the former played a more important role.

Abstract:Development of scale pig farming and its impacts on circumjacent soil and water environment in Yujiang County, Jiangxi Province, a red soil hilly region typical of South China were selected for case study. It was found that the county had 389 scale pig farms, turning out a total of 7.32×10⁵ heads in 2011. Of the pig farms, 50.6% had an annual production capacity of 1 000~5 000 heads each. These pig farms were mainly distributed in the low-hilly areas in the center and south of Yujiang County, particularly alongside State Highway No.320. They turned out annually a total of 2.96×10⁵ t, 4.64×10⁵t and 1.09×10⁶ t of pig dung, urine and wastewater, respectively, with which a total of 1.96×10⁴ t, 3.27×10³ t, 1.25×10³ t, 50 t and 116 t of COD, N, P, Cu, and Zn, respectively, was discharged annually as pollutants. On such a basis this county is estimated to have 1.1 million heads of pigs, which may produce annually a total of 4.47×10⁵ t, 7.00×10⁵ t and 1.09×10⁶ t of dung, urine and wastewater, respectively, with which a total of 2.96×10⁴t, 4.94×10³ t, 1.89×10³ t, 76 t and 176 t of COD, N, P, Cu and Zn is discharged, respectively. Sampling analysis shows that 90.9% of the ponds and 66.6% of the reservoirs and 50% of the rivers in their surroundings are in Sub-Grade V in water quality largely due to total nitrogen beyond the limit, and the soils nearby were badly unbalanced, with available P over-accumulated and heavy metals like Cu and Zn significantly accumulated. It is therefore essential to strengthen planning in development of pig farming in the region, and intensify research on technologies for deharming and recycling of pig dung, urine and wastewater, hence to promote healthy development of scale pig farming and environment protection in red soil hilly areas of South China.

Abstract:Samples of paddy soil were prepared into slurry and then incubated anaerobically at a constant temperature for exploration of effects of illumination on reduction of sulfate and redox of iron in the soil. Water soluble inorganic carbon and organic carbon in the soil were analyzed simultaneously for relationship of anaerobic redox process of iron with sulfur and carbon transformation under illumination in the paddy soil. Results showed that illumination is a key environmental factor regulating geomicrobiological cycling of iron and sulfur. Inhibitive effect of illumination on reduction of iron and sulfur was observed after 5 days of anaerobic incubation. After 30 days of anaerobic incubation in the dark, 70.07% of free iron was reduced in the soil; and in the soil incubated under illumination, 35.60 μmol g⁻¹ Fe(III) was reduced first and then re-oxidized, and after 30-days, the soil still had 32.70% of its free iron reduced. After the illumination was turned off those oxidized Fe could once again be reduced and 99.50% of the water soluble sulfate in the soil was reduced within 5 days. In soils anaerobically incubated for 30 days under illumination, 42.73% of the WSS was reduced. The date when the maximum reaction rate of iron reduction or oxidation appeared came prior to the date when maximum reaction rate of sulfur transformation was observed. Close relationship of water soluble inorganic carbon with Fe(II) and water soluble sulfate in the soil were found, and significant positive relationships were also found of water soluble organic carbon (WSOC) with iron or sulfur transformation rate in the soil under incubation without shifting between illumination and darkness. In the soil under dark incubation when WSOC in the soil was > 7.89 μmol g⁻¹, Fe(III) and water soluble sulfate (WSS) tended to be reduced, while in the soil under illuminated incubation, when WSOC was > 8.27 μmol g⁻¹, Fe(III) did and when WSOC was > 8.40 μmol g⁻¹, WSS did.

Abstract:In order to explore mechanisms of tea plant roots acidifying soils, a hydroponic experiment was carried out using the method of automatic potentiometric titration to investigate effects of different forms of nitrogen, i.e. NH₄⁺-N, NO₃^--N and ammonium nitrate, on proton release from tea plant roots in the solution of constant pH. Results show that tea plant roots released protons in the presence of ammonium at a higher rate than they did in the solution containing ammonium and nitrate with mole ratio of NH₄⁺/ NO₃^-=1:1; but they released hydroxyl in the presence of nitrate. The release of proton release was positively related the initial concentration of ammonium in the solution and with the uptake of ammonium by tea plant roots, too. Within the range of pH from 4.5 to 5.5, the maximum proton occurred in the treatment with initial pH being 5.0, and then in the treatment with initial pH being 5.5, and the least in the treatment with initial pH being 4.5. To culture tea plants with ammonium nitrate solution validated the plant’s ammoniaphilic feature. It was found that longer duration of incubation in ammonium nitrate solution increased the plant’s uptake of both ammonium and nitrate and its release of proton as well. However, at the end of the incubation, the plants were found to have absorbed more ammonium than nitrate. The findings suggest that tea plants preferred to absorb ammonium, which leads to release of more protons from their roots, thus causing acidification of the soil in tea gardens.

Abstract:Phosphorus sorption and desorption characteristics of gray desert soil (0~20 cm) under long-term fertilization as affected by phosphorus content level were studied through an isothermal P adsorption and desorption experiment. Results show that within the range of P concentrations set for the experiment, in all the gray desert soil samples, regardless of Olsen-P level, P adsorption, P desorption and P desorption rate gradually increased and P adsorption rate gradually decreased, with the increasing amount of extraneous phosphorus added. A positive correlation was observed between Olsen-P content and phosphorus sorption saturation ( DPS) in the soil. In terms of soil maximum adsorption capacity ( Xm), the treatments of the experiment followed a decreasing order of CK > NPK ≈ NPKM > PK ≈ NPKS, and the differences between the treatments were extremely significant; Treatment NPK was much higher than CK and Treatments PK, NPKM and NPKS in adsorption constant (K) and maximum buffer capacity (MBC). And the comparison between last four treatments showed no significant difference in K value, and CK was extremely higher than Treatments PK and NPKS in MBC value, but the difference between CK and Treatment NPKM, and between Treatments PK and NPKS was not significant. Treatments NPKM and NPKS were significantly higher than Treatments NK and NPK in RDP, and Treatment NPKM was the highest in P desorption rate.

Abstract:Aggregate stability is an important physical property of soils. As is known, organic macromolecules enhance stability of aggregates, while soil electric field acts reversely. Therefore, effect of coupling of electric field and organic macromolecules on soil aggregate stability, yet still unknown, is worthy of exploring. KNO₃ and Ca(NO₃)₂ solutions, different in concentration were used to adjust strength of soil electric field and humus and PAM added to control molecular attraction forces between soil particles in this experiment. Aggregate stability is characterized by content of the particles (<10 μm, <5 μm and <2 μm in particle size) released from aggregates after their breakdown. Results show that soil electric field plays a crucial role in breaking aggregates. When the electric field is strong enough, soil aggregates are likely to break up violently, no matter whether there exist organic macromolecules or not. Soil aggregates are ready to break down when they get wet. Addition of organic macromolecules significantly reduces the degree of aggregate breakdown by as much as 60% under the same electric field. Because of varying extent of the coupling between electric field and humus/PAM, clear discrepancies exist in extent of the breakdown. Strong electric field may lead to violent breakdown or explosion of aggregates. With increasing addition rate of organic macromolecules, the threshold potential triggering the explosion of aggregates declined correspondingly.

Abstract:High fertilizer N application rate and low nitrogen use efficiency are two typical problems in vegetable farming systems in China. To explore quantitatively relationship between N₂O emission rate and fertilizer N application rate and its mechanism, and effect of nitrification inhibitors in mitigating N₂O emission, a field experiment was carried out having four crops of vegetable and lasting one year. Results show that when the N application rate varied in the range of 0~1 733 kg hm^-2 a^-1, the total N₂O emission increased exponentially with N application rate, no matter with or without the addition of any nitrification inhibitor, that is to say, the higher the N application rate, the higher the N₂O emission rate. The application of nitrification inhibitor reduced N₂O emission (8.75%~25.28%) from the soils of all the N fertilization treatments, and the mitigation effect increased with N application rate. In plots applied with N 300 or 400 kg hm^-2 season^-1, the economic benefit arising from reduction of N₂O emission as a result of the use of the nitrification inhibitor was higher than the cost of the nitrification inhibitor. Therefore, the use of nitrification inhibitors is a profitable option even without considering some other factors like improving N use efficiency.

Abstract:A pot experiment was carried out to study effects of soil temperature and soil salinity on soil physico-chemical properties and enzyme activity in the soil as well as dry matter accumulation, nutrient uptake and distribution of cucumber. The experiment was designed to have 3 levels of soil temperature (10℃ as control, 18℃ and 26℃) and 3 levels of salinity (1# > 2# > 3#). Results showed that compared with control, 18℃ and 26℃ wiped out the obstacle of low soil temperature for growth of the plant in winter, promoted normal growth of cucumber seedlings and provided the plants with guarantee to blossom and yield. With soil temperature rising from 18℃ to 26℃, cucumber fruit dry weight increased by 41.84%, 15.49%, and 3.59% in soil 1#, soil 2# and soil 3#, respectively, demonstrating that the effect of higher soil temperature was more significant in soils high in salt content. Higher soil temperature increased total nutrient (N, P and K) uptake of the plant, promoted transfer of nutrients from roots to shoots and reduce the contents of readily available nutrients (alkalysitc N, readily available P and readily available K) in the soil. Higher soil temperature significantly increased urease activity, but did not have much effect on the activities of phosphatase and catalase. Therefore, raising soil temperature in winter can increase cucumber yield, promote soil nutrient transformation and improve soil nutrient utilization efficiency.

Abstract:Comparisons were made between treatments of a long-term stationary experiment in a field of aquic brown soil in the lower reaches of the Liaohe River Plain for analysis of effects of type and application rate of fertilizer on distribution of total phosphorus (TP) in the surface soil layer and of available phosphorus (AP) throughout the soil profile (0~80cm). Result show that in all the treatments receiving fertilizer P, soil P gained in positive budget of TP in the surface soil layer and AP increasing obviously , and a significant linear relationship was found between budget of soil P (x) and balance of AP (y) y = 0.070 1x +8.538 9 (R²=0.89**). About 15.8% of the surplus P entered AP pool. When P application rate went beyond 50 kg hm^-2, the AP content in the 60~80 cm soil layer was significantly higher than that in the control, suggesting that vertical transport of P existed. Compared with chemical fertilizer, organic manure is more likely to cause downwards transport of P. Affected by a number of factors, like fertilizer, organic matter content, crop uptake, etc., the distribution of soil available phosphorus in the soil profile showed a pattern of being high in the upper and lower layers and low in the middle layer, with the lowest observed in the 20~40 cm soil layer.

Abstract:The ultrafine activated rock phosphate (UARP) was prepared and its phosphorus availability and fertilizer efficiency as affected by amendment of activator and grinding was studied using chemical analysis, infrared spectrum (IR) analysis and pot experiment. Results show that the fractions of available phosphorus and labile phosphorus in UARPs increased by 45.12%~58.68% and 169.4%~203.6%, respectively. The fraction of water-soluble phosphorus in UARPs increased markedly with the amount of activator added. When the activator was added to make 5% of the UARP, the accumulative water-soluble phosphorus release rate of the fertilizer increased by more than 84 times. Proper extension of grinding time contributed to release of phosphorus from the product, but the effect was not significant. Infrared spectrum (IR) analysis shows that the PO₄^3- and HPO₄^2--related characteristic absorption peaks of UARPs were much higher in intensity than those of common RP, thus forming new characterastic absorption peaks, which indicates that phosphorus in rock phosphate powder is turned to be available. Results of the pot experiment indicate that treatment UARP was much higher than treatments RP and UFRP in corn biomass and fertilizer use efficiency, and even higher than treatments SP (superphosphate) and DAP (diammonium phosphate), and that UARP significantly increased available phosphorus by reducing fixation of phosphorus in the soil. The relatively high content of labile phosphorus and the sustained moderate phosphorus supply level of water-soluble phosphate in UARP were the main causes of its high bioavailability.

Abstract:Soil samples were collected in every season of a year from the plow layer of a long-term fertilization experimental field at the Fengqiu Agro-ecological Experimental Station, Fengqiu County, Henan Province, China, for investigation of effects of fertilization regimes on population of soil Bacilli and its proportion to the total of bacteria, and for analysis of relationship between population of Bacilli and soil fertility. The long-term fertilization experiment consisted of seven treatments, i.e. organic manure (OM), half the rate of organic manure plus half the rate of N fertilizer (1/2OMN), fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilizer), of which each had four replicates. Results show that long-term fertilization, especially in treatments that involved organic manure and fertilizer P, increased the contents of soil organic C, total N, available N, P and K, and the increase in soil organic C varied in the range of 0.91~7.00 g kg^-1 in all the fertilization treatments, except treatment NK. Regime of the long-term fertilization also significantly affected populations of Bacilli and soil bacteria, which showed steady gradients in all the seasons, that is, the populations were significantly higher in all the fertilization treatments, except NK than in the control; in the treatments involving organic manure than in the treatments involving chemical fertilizers only; and in the treatment of balanced fertilization than in the treatments missing any one element. The population of Bacilli increased in all the treatments except treatment NK by a range of 0.02~0.54 lg (CFU g^-1) as compared that in the control. The ratio of Bacilli/bacteria was higher in summer and winter than in spring and autumn in all the chemical fertilizer treatments and relatively stable throughout the year in the treatments involving OM. Correlation analysis that the population of Bacilli was closely related to the contents of soil organic carbon and available P (p<0.01). All the findings demonstrate that, long-term application of organic manure is more conducive to build-up of soil fertility and growth and propagation of soil microbes, and that the population of Bacilli is a sensitive indicator of soil fertility.

Abstract:Zoigȇ alpine wetland meadow, located on the eastern edge of the Qinghai-Tibetan Plateau, is degrading under the impact of global climate change and the increasingly heavy burden of livestock in recent years, demonstrating four typical phases，i.e. swampy meadow, grassland meadow, degraded meadow and desertifying meadow in the process. From April 2009 to October 2010, seven investigations were conducted of soil macrofauna communities in the four phases for analysis of impacts of the degradation on soil macrofauna. Results show that differences existed between the phases in taxonomic composition and dominant groups of the soil macrofauna communities. Statistical analysis shows that the impacts of the degradation on richness, density and Shannon diversity index of the soil macrofauna communities were extremely significant (p<0.01 or p<0.05) in the last two phases. Principal Component Analysis (PCA) shows that in the phase of graded meadow, Polydesmida and Coleoptera larvae increased significantly (p<0.05), while in the phase of desertifying meadow the dominant groups decreased significantly in density (p<0.05) and some common and rare groups disappeared. Correlation analysis shows that richness, density and diversity of soil macrofauna communities were closely related to species and biomass of the plants and physical and chemical properties of the soils (p<0.01 or p<0.05), especially available phosphorus and readily available potassium, in the meadows. And soil macrofauna communities also responded to changes in season significantly in abundance and diversity, and the responses varied from phase to phase of the degradation process (p<0.01 or p<0.05). All the findings indicate that moderate degradation of alpine meadows may increase soil macrofauna community in diversity, whereas severe degradation (desertification) significantly reduces the diversity, and moreover, seasonal dynamics of soil macrofauna communities varies from phase to phase of the degradation process.

Abstract:Composition and structure of cropland soil fauna as affected by exogenous carbon and nitrogen was studied in the black soil area of Jilin in 2011, using Hand-sorting, modified Tullgren and Baermann’s methods. The field under study was designed to have seven treatments of exogenous carbon and nitrogen, separately, i.e. control (CK), exogenous carbon (C0.5, C1.0, C2.0) and exogenous nitrogen (N0.5, N1.0, N2.0). A total of 56 886 soil fauna individuals were obtained after 5 times of gathering during the crop growing season from May to September, and sorted into 79 families, 3 suborders, 23 orders, and 11 classes under 3 phyla, including 80 unidentified individuals. The data obtained show that the cropland soil fauna lived mainly in the 0～5 cm soil layer and decreased with soil depth in population; as compared with the control (CK), the treatments with exgenous carbon increased the number of individuals and groups of soil fauna in the field with a trend increasing with the concentration of exgenous carbon; and the treatments with exgenous nitrogen decreased the number of individuals of soil macro fauna, but increased the numbers of individuals of soil meso-and micro-fauna, showing a trend of the more the less and the more the more, respectively. During the crop growing season, cropland soil fauna rose in number of individuals and groups from May to August and then declined in September. Variance analysis of the data shows that the impacts of exogenous carbon and nitrogen on soil macro-, meso-and micro-fauna in number of individuals and groups were significant (p＜0.01); and the cropland soil fauna varied significantly in number of individuals and groups (p＜0.01) during the crop growing season. The numbers of individuals and groups of soil meso-and micro-fauna and the number of groups of soil macro-fauna were closely related with the concentration of nutrients released from exogenous carbon and nitrogen sources. Exogenous carbon favors guilds of soil fauna and diversification of the composition of the cropland soil fauna community.

Abstract:Morphological, cultural and physio-biochemical traits and 16S rRNA sequence was analyzed of a strain of actinomycete, separated from the soil of the Zijin Mountain in Nanjing, China and coded as CT205, for identification and orientation in the classification system. The PDA agar plate method was used to determine antifungal activity of Strain CT205 and a pot experiment using pathogenic soil from a field that had been cultivated with cucumber consecutively for year was conducted to investigate the effect of Stain CT205 controlling cucumber Fusarium wilt. Based on the 16S rRNA sequence analysis, Strain CT205 was tentatively identified as Streptomyces albospinus (99% identity). And the pot experiment showed that the strain inhibited quite effectively Fusarium oxysporum f. sp. cucumerinum, Fusarium oxysporum f. sp. niveum, and Phytophthora nicotianae, and to a varying extent, Bacillus subtillus, Saccharomyces cerevisiae, Rhizoctonia cerealis, Ralstonia solanacearum. Besides its cucumber Fusarium wilt controlling efficiency being 51.85%, the strain promoted somewhat the growth of cucumber. When the strain was prepared with organic manure into complex biomanure, the disease controlling efficiency may reach as high as 81.85%. The findings demonstrate that the strain has certain potential application value.

Abstract:To explore effect of latitude on ecological stoichiometry characteristics of Robinia pseudoacaciaforest soil on the Loess Plateau, soil samples were collected from Robinia pseudoacacia forests in 13 counties distributed from south to north in Northern Shaanxi for analysis of soil C, N and P stoichiometry. Results show that (1) on sunny slopes, the ranges of soil C:N, C:P, N:P ratios varied in the range of 9.48~15.33, 8.93~59.79 and 0.77~5.11 respectively, in the 0~10cm soil layers and in the range of 9.13~13.57, 7.85~37.69 and 0.44~3.19, respectively, in the 10~20cm soil layer, while on shady slopes, they did in the range of 8.58~13.75, 9.46~47.71 and 0.76~3.63, respectively, in the top soil layers and in the range of 7.60~13.41, 5.99~31.28 and 0.54~2.65, respectively, in the 10~20cm soil layers. (2) Soil organic carbon and soil total N were quite consistent in spatial distribution, showing the same trend of declining exponentially with rising latitude and they were higher in the surface layers than in the subsurface layers, and the difference narrowed with rising latitude; Total P was lower than SOC and total N in spatial variability, showing a trend of rising first and then declining with latitude in the studied area. (3) Soil C:N ratio did not change much with latitude, while soil C:P and N:P ratios decreased significantly with rising latitude; and soil C:N:P ratio was higher in the topsoil layers than in the subsurface soil layer, but the difference was not significant.

Abstract:This paper is an introduction to the Principles and Criteria for Establishment of Soil Family and Soil Series in Chinese Soil Taxonomy. The background, principles, and characteristics of the criteria followed by the criteria itself are described in details. Then an example is given to demonstrate the application of the criteria on specific soils.

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