[Objective] The research aimed to provide the reference for the precise formula and balanced fertilization of tobacco production in Fuquan City, Guizhou Province. [Method] 180 soil samples were gathered from Fuquan Ci...[Objective] The research aimed to provide the reference for the precise formula and balanced fertilization of tobacco production in Fuquan City, Guizhou Province. [Method] 180 soil samples were gathered from Fuquan City by Global Position System （GPS） fixed position. The main nutrient contents and pH value were analyzed. [Result] The average contents of organic matter, available nitrogen, available phosphorus, available potassium in tobacco planting soil were 26.8 g/kg, 134.1 mg/kg, 35.9 mg/kg, and 222.1 mg/kg respectively, and the coefficient of vari- ation were 25.8%, 21.4%, 72.1%, and 55.3% respectively. The pH value of tobacco planting soil was 6.2, and the pH value coefficient of variation was 15.3%. [Conclu. sien] The organic matter, available nitrogen, available phosphorus, available potassi- um contents were abundant in the mass, but there were big difference among dif- ferent towns. The precise fertility types and precise fertility dosage should be deter- mined according to the main nutdent state and pH value of tobacco planting soil in Fuquan city.展开更多
[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated ...[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated in this study,and soil available N,P,K,Cu,Zn,organic matter and pH value were also analyzed by routine analysis of soil nutrients in different degraded grasslands.[Result]With the intensification of degraded gradient and the soil depth,the ratio of plant root to soil was decreased gradually.The highest ratio of plant root to soil was in 0-10 cm depth of soil in grassland with different degraded gradients,while its ratio of plant root to soil changed from 0.001 to 0.040 with soil type of loam.Soil chemical characteristic changed in different degraded gradients.The content of available N,P,K reduced significantly with the soil depth and the intensification of degraded gradients.The content of Cu and Zn was relatively lack in degraded grassland.[Conclusion]There is no significant correlation between nutrition content or pH value and the succession degree of degraded grassland.展开更多
In order to find out the main nutrient content of tobacco planting soil and the changing characteristics of tobacco quality in Linli County,the sampling survey data of tobacco planting soil samples in Linli in 2000 an...In order to find out the main nutrient content of tobacco planting soil and the changing characteristics of tobacco quality in Linli County,the sampling survey data of tobacco planting soil samples in Linli in 2000 and 2015,and the main chemical components,appearances and sensory qualities and physical indexes of B2F and C3F tobacco leaves from 2000 to 2015 were comprehensively analyzed and evaluated.The results showed that:the available phosphorus increased by 6.10%per year and the pH value of tobacco planting soil increased in a small range year by year,the organic matter content decreased year by year,the alkali hydrolyzable nitrogen showed a downward trend,and the water-soluble chlorine showed a rapid downward trend;the soil fertility index(SFI)was at the"high"level;in 2000—2015,the quality of tobacco leaf was relatively stable and the quality was good.In Linli tobacco planting area,the application of nitrogen control,phosphorus reduction and chlorine supplement and increase of organic matter could help us achieve the goal of high quality and efficiency of tobacco production.展开更多
There is an increasing concern that the continuous use of chemical fertilizers might lead to harmful effects on soil ecosystem.Accordingly, a biocompatible approach involving inoculation of beneficial microorganisms i...There is an increasing concern that the continuous use of chemical fertilizers might lead to harmful effects on soil ecosystem.Accordingly, a biocompatible approach involving inoculation of beneficial microorganisms is presented to promote plant growth and simultaneously minimize the negative effect of chemical fertilizers. In this study, Rhodopseudomonas palustris, a plant growth-promoting rhizobacterium(PGPR), was inoculated into both fertilized and unfertilized soils to assess its influence on Stevia rebaudiana plant growth and microbial community in rhizosphere soils in a 122-d field experiment. Soil enzyme assays(dehydrogenase, urease, invertase, and phosphomonoesterase), real-time quantitative polymerase chain reaction(RT-_qPCR), and a high-throughput sequencing technique were employed to determine the microbial activity and characterize the bacterial community. Results showed that the R.palustris inoculation did not significantly influence Stevia yields and root biomass in either the fertilized or unfertilized soil. Chemical fertilization had strong negative effects on soil bacterial community properties, especially on dehydrogenase and urease activities.However, R. palustris inoculation counteracted the effect of chemical fertilizer on dehydrogenase and urease activities, and increased the abundances of some bacterial lineages(including Bacteroidia, Nitrospirae, Planctomycetacia, Myxococcales, and Legionellales). In contrast, inoculation into the unfertilized soil did not significantly change the soil enzyme activities or the soil bacterial community structure. For both the fertilized and unfertilized soils, R. palustris inoculation decreased the relative abundances of some bacterial lineages possessing photosynthetic ability, such as Cyanobacteria, Rhodobacter, Sphingomonadales, and Burkholderiales. Taken together, our observations stress the potential utilization of R. palustris as PGPR in agriculture, which might further ameliorate the soil microbial properties in the long run.展开更多
Urban forest soil infiltration, affected by various factors, is closely related with surface runoff. This paper studied the effect of urban forest types, vegetation configuration and soil properties on soil infiltrati...Urban forest soil infiltration, affected by various factors, is closely related with surface runoff. This paper studied the effect of urban forest types, vegetation configuration and soil properties on soil infiltration. In our study, 191 typical plots were sampled in Changchun City, China to investigate the soil infiltration characteristics of urban forest and its influencing factors. Our results showed that the steady infiltration rates of urban forest soil were highly variable. High variations in the final infiltration rates were observed for different vegetation patterns and compaction degrees. Trees with shrubs and grasses had the highest infiltration rate and trees with bare land had the lowest infiltration rate. In addition, our results showed that the soil infiltration rate decreased with an increase in the bulk density and with a reduction in the soil organic matter content and non-capillary porosity. The soil infiltration rate also had significantly positive relationships with the total porosity and saturated soil water content. Urban soil compaction contributed to low soil infiltration rates. To increase the infiltration rate and water storage volume of urban forest soil, proper techniques to minimize and mitigate soil compaction should be used. These findings can provide useful information for urban planners about how to maximize the water volume of urban forest soil and decrease urban instantaneous flooding.展开更多
Limited availability of organic matter is a problem to sustain crop growth on sodic soil. Organic soil amendments are a costeffective source of nutrients to enhance crop growth. A field study was conducted to evaluate...Limited availability of organic matter is a problem to sustain crop growth on sodic soil. Organic soil amendments are a costeffective source of nutrients to enhance crop growth. A field study was conducted to evaluate the effect of an organic soil amendment bioaugmented with plant growth-promoting fungi(SF_(OA) ) in combination with gypsum on soil properties and growth and yield attributes of Withania somnifera, one of the most valuable crops of the traditional medicinal system in the world, on a sodic soil at the Aurawan Research Farm of CSIR-National Botanical Research Institute, Lucknow, India. The SF_(OA) used was prepared by pre-enriching farm waste vermicompost with plant growth-promoting fungi before mixing with pressmud and Azadirachta indica seed cake. The application of SF_(OA) at 10 Mg ha^(-1)after gypsum(25.0 Mg ha^(-1)) treatment significantly(P < 0.05) increased root length(by 96%) and biomass(by 125%) of Withania plants compared to the control without SF_(OA) and gypsum. Similarly, the highest withanolide contents were observed in leaves and roots of Withania plants under 10 Mg ha^(-1)SF_(OA) and gypsum. Combined application of SF_(OA) and gypsum also improved physical, chemical and enzymatic properties of the soil, with the soil bulk density decreasing by 25%, water-holding capacity increasing by 121%, total organic C increasing by 90%, p H decreasing by 17% and alkaline phosphatase, β-glucosidase, dehydrogenase and cellulase activities increasing by 54%, 128%, 81% and 96%, respectively, compared to those of the control. These showed that application of the SF_(OA) tested in this study might reclaim sodic soil and further support Withania cultivation and results were better when the SF_(OA) was applied after gypsum treatment.展开更多
Hydrology plays a dominant role in wetland plant distribution and microbial composition, but few studies explicitly attempted to relate the linkage between wetland vegetation and microbial community. The present study...Hydrology plays a dominant role in wetland plant distribution and microbial composition, but few studies explicitly attempted to relate the linkage between wetland vegetation and microbial community. The present study consisted of five wetland plant communities along three adjacent flood gradients zones(zone 1 dominated by Carex appendiculat, zone 2 dominated by Eleocharis ovate, and zone 3 dominated by Phragmites australis/Bidens pilosa/Calamagrostis angustifolia, which formed separate, monoculture patches). Gram negative and arbuscular mycorrhizal fungal phospholipid fatty acid(PLFA) are more abundant in the site with short flooding period(zone 3) than in the site with long flooding period(zone 1), and they are also different in the P. australis, B. spilosa and C. angustifolia of zone 3. Principle Component Analysis(PCA) showed that the flooding period could explain 92.4% of variance in microbial composition. Redundancy Analysis(RDA) showed that available nitrogen(AN), total nitrogen(TN) and soil organic matter(SOM) could explain the 79.5% of variance in microbial composition among E. ovata, P. australis, B. pilosa and C. angustifolia. Results demonstrated that flooding period was the main factor in driving the microbial composition and plant-derived resources could influence soil microbial composition in the seasonally flooded zones.展开更多
Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt...Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.展开更多
Both climate and land-use changes,including the introduction and spread of allochthonous species,are forecast to affect forest ecosystems.Accordingly,forests will be affected in terms of species composition as well as...Both climate and land-use changes,including the introduction and spread of allochthonous species,are forecast to affect forest ecosystems.Accordingly,forests will be affected in terms of species composition as well as their soil chemical and biological characteristics.The possible changes in both tree cover and soil system might impact the amount of carbon that is stored in living plants and dead biomass and within the soil itself.Additionally,such alterations can have a strong impact on the detrital food web that is linked to litter decomposition.Although there are studies on the infuence of plant diversity on soil physical and chemical characteristics,the effects on soil biological activity and carbon storage processes remain largely unknown.The aim of this study was to investigate and compare chemical and biological variables in covariation with plant communities in an autochthonous beech forest(Fagus sylvatica L.)and a black pine plantation(Pinus nigra J.F.Arnold subsp.nigra).Our results confirmed that the two communities were considerably different,with the old-growth beech community having a lower number of plant species and the pine community was in development as a consequence of anthropogenic activities.These aspects of the two communities were also refected in the soil,with the beech soil having higher nitrogen levels and a more specialized microbial community compared to the pine soil,with most extracellular enzymes(such as peroxidase and chitinase)showing lower activity in the pine soil.展开更多
Grazing can modulate the feedback between vegetation and soil nutrient dynamics（carbon and nitrogen）,altering the cycles of these elements in grassland ecosystems.For clarifying the impact of grazing on the C and N ...Grazing can modulate the feedback between vegetation and soil nutrient dynamics（carbon and nitrogen）,altering the cycles of these elements in grassland ecosystems.For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia,China,we examined the plant biomass,SOC（soil organic carbon）,total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites.Significantly lower aboveground biomass,root biomass,litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site,with decreases of 42.0%,16.2%,59.4% and 30.0%,respectively.The effects of grazing on plant carbon,nitrogen,？15N and ？13C values were uniform among species.The levels of plant carbon and nitrogen in grasses were greater than those in the forbs（except for the carbon of Cynanchum komarovii and Euphorbia esula）.Root 15 N and 13 C values increased with grazing,while the responses of root carbon and nitrogen to grazing showed no consistent patterns.Root 15 N and 13 C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site,respectively.The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths（0–10 and 10–20 cm）,and values of SOC and total N at the surface（0–10 cm） were lower than those in the deeper soils（10–20 cm）.Soil ？15N values were not affected by grazing at any sampling depth,whereas soil ？13C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0–10 and 10–20 cm,respectively.The soil ？13C values（–8.3‰ to –6.7‰） were higher than those for roots（–20.2‰ to –15.6‰） and plant tissues（–27.9‰ to –13.3‰）.Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.展开更多
Studies were conducted to identify candidate soil microbes responsible for observed differences in strawberry vigour at a small spatial scale, which was not associated with visual disease symptoms. Samples were obtain...Studies were conducted to identify candidate soil microbes responsible for observed differences in strawberry vigour at a small spatial scale, which was not associated with visual disease symptoms. Samples were obtained from the soils close to the rhizosphere of ‘big＇ and ‘small＇ plants from small plots which exhibited large local heterogeneity in plant vigour. A metabarcoding approach was used to profile bacterial and fungal compositions, using two primer pairs for 16 S ribosomal RNA genes（16S r DNA） and one for the fungal internal transcribed spacer（ITS） region. Of the two 16 S r DNA primer sets, the 341F/805 R resulted in sequences of better quality. A total 28 operational taxonomic units（OTUs） had differential relative abundance between samples from ‘big＇ and ‘small＇ plants. However, plausible biological explanation was only possible for three fungal OTUs. Two were possible phytopathogens： Verticillium spp. and Alternaria alternata although the latter has never been considered as a main pathogen of strawberry in the UK. For samples from ‘small＇ plants, the abundance of these OTUs was much greater than from ‘big＇ plants. The opposite was true for a mycorrhizal OTU. These results suggest that soil microbes related to crop production can be identified using metabarcoding technique. Further research is needed to assess whether A. alternata and Verticillium spp. could affect strawberry growth in the field.展开更多
Soil water deficit is increasingly threatening the sustainable vegetation restoration and ecological construction on the Loess Plateau of China due to the climate warming and human activities.To determine the response...Soil water deficit is increasingly threatening the sustainable vegetation restoration and ecological construction on the Loess Plateau of China due to the climate warming and human activities.To determine the response thresholds of Amygdalus pedunculata(AP)and Salix psammophila(SP)to soil water availability under different textural soils,we measured the changes in net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),leaf water potential(ψw),water use efficiency(WUE)and daily transpiration rate(Td)of the two plant species during soil water content(SWC)decreased from 100%field capacity(FC)to 20%FC in the sandy and loamy soils on the Loess Plateau in the growing season from June to August in 2018.Results showed that Pn,Gs,WUE and Td of AP and SP remained relatively constant at the beginning of soil water deficit but decreased rapidly as plant available soil water content(PASWC)fell below the threshold values in both the sandy and loamy soils.The PASWC thresholds corresponding to Pn,Gs and Ci of AP in the loamy soil(0.61,0.62 and 0.70,respectively)were lower than those in the sandy soil(0.70,0.63 and 0.75,respectively),whereas the PASWC thresholds corresponding to Pn,Gs and Ci of SP in the loamy soil(0.63,0.68 and 0.78,respectively)were higher than those in the sandy soil(0.58,0.62 and 0.66,respectively).In addition,the PASWC thresholds in relation to Td and WUE of AP(0.60 and 0.58,respectively)and SP(0.62 and 0.60,respectively)in the loamy soil were higher than the corresponding PASWC thresholds of AP(0.58 and 0.52,respectively)and SP(0.55 and 0.56,respectively)in the sandy soil.Furthermore,the PASWC thresholds for the instantaneous gas exchange parameters(e.g.,Pn and Gs)at the transient scale were higher than the thresholds for the parameters(e.g.,Td)at the daily scale.Our study demonstrates that different plant species and/or different physiological parameters exhibit different thresholds of PASWC and that the thresholds are affected by soil texture.The result can provide guidance for the rational allocation and sustainable management of reforestation species under different soil conditions in the loess regions.展开更多
The characteristics of vertical and horizontal variations of lead element(Pb) in soil plant system of vertical zone in Changbai Mountain National Nature Reserve(CNNR) were studied. The results showed that Pb concentr...The characteristics of vertical and horizontal variations of lead element(Pb) in soil plant system of vertical zone in Changbai Mountain National Nature Reserve(CNNR) were studied. The results showed that Pb concentrations in soils of vertical zone are all above 25 mg/kg, and the average Pb concentration of each soil zone negatively correlates its degree of variation, i.e. brown coniferous forest soil zone has the lowest average Pb concentration of four soil zones, and the highest horizontal variation; however, mountain soddy forest soil has the highest average Pb concentration, and the lowest horizontal variation; the average concentration of plant Pb of each plant zone is lower than the worldwide average level of Pb in plant(Clarke), respectively, and plant Pb content order is consistent with soil Pb content order, but their horizontal variations are different from those in soil zones, the variation of mountain tundra forest zone is highest, but Betula ermanii forest zone the lowest. Vertical variation of plant Pb is obviously higher than that in soils with variation coefficient of 89.76%; the enrichment capability of plant for Pb is depended on the plant types and the different organs of plant; parent material and parent rock, pH values, soil organic matter and soil particle fraction etc. are the main factors influencing variations of Pb content in soil plant system of vertical zone in CNNR.展开更多
Nitrogen is an essential component in forest ecosystem nutrient cycling.Nitrogen fractions,such as dissolved nitrogen,ammonium,nitrate,and microbial biomass nitrogen,are sensitive indicators of soil nitrogen pools whi...Nitrogen is an essential component in forest ecosystem nutrient cycling.Nitrogen fractions,such as dissolved nitrogen,ammonium,nitrate,and microbial biomass nitrogen,are sensitive indicators of soil nitrogen pools which affect soil fertility and nutrient cycling.However,the responses of nitrogen fractions in forest soils to organic mulching are less well understood.The rhizosphere is an important micro-region that must be considered to better understand element cycling between plants and the soil.A field investigation was carried out on the effect of mulching soil in a 15-year-old Ligustrum lucidum urban plantation.Changes in total nitrogen and nitrogen fractions in rhizosphere and bulk soil in the topsoil(upper 20 cm)and in the subsoil(20-40 cm)were evaluated following different levels of mulching,in addition to nitrogen contents in fine roots,leaves,and organic mulch.The relationships between nitrogen fractions and other measured variables were analysed.Organic mulching had no significant effect on most nitrogen fractions except for the rhizosphere microbial biomass nitrogen(MBN),and the thinnest(5 cm)mulching layer showed greater effects than other treatments.Rhizosphere MBN was more sensitive to mulching compared to bulk soil,and was more affected by soil environmental changes.Season and soil depth had more pronounced effects on nitrogen fractions than mulching.Total nitrogen and dissolved nitrogen were correlated to soil phosphorus,whereas other nitrogen fractions were strongly affected by soil physical properties(temperature,water content,bulk density).Mulching also decreased leaf nitrogen content,which was more related to soil nitrogen fractions(except for MBN)than nitrogen contents in either fine roots or organic mulch.Frequent applications of small quantities of organic mulch contribute to nitrogen transformation and utilization in urban forests.展开更多
Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two question...Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.展开更多
Deserts have traditionally been considered as a low moisture system where biological activity is triggered by unpredictable rainfall in time and space. Studies on desert ecosystems functions, processes, dynamics and d...Deserts have traditionally been considered as a low moisture system where biological activity is triggered by unpredictable rainfall in time and space. Studies on desert ecosystems functions, processes, dynamics and diversity of soil biota had been found to contribute to understanding of their role in primary production and management of soil ecosystems. As belowground biota is very diverse they are playing an important role in above as well below ground essential ecosystem processes e.g. primary production, decomposition, nutrient mineralization etc. The challenge is to use the emerging knowledge of soil biota diversity in understanding basic ecosystems function.展开更多
Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslan...Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna(Vicugna vicugna) and alpaca(Lama pacos). The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined: total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.展开更多
A field experiment with a split-plot design was carried out at Dongbeiwang Farm in Beijing Municipality to establish reliable N fertilizer recommendation indices for summer maize (Zea mays L.) in northern China using ...A field experiment with a split-plot design was carried out at Dongbeiwang Farm in Beijing Municipality to establish reliable N fertilizer recommendation indices for summer maize (Zea mays L.) in northern China using the soil Nmin (mineral N) test as well as the plant nitrate and SPAD (portable chlorophyll meter readings) tests. The results showed that Nmin sollwert (NS) 60 kg N ha-1 at the third leaf stage and N rate of 40 to 120 kg N ha-1 at the tenth leaf stage could meet the N requirement of summer maiz…展开更多
Split fertilization strategy is popularly adopted in rice to synchronize soil nitrogen(N) supply and crop N demand. Attention has been paid more on mid-season topdressing N, but limited on basal N. A clearer understan...Split fertilization strategy is popularly adopted in rice to synchronize soil nitrogen(N) supply and crop N demand. Attention has been paid more on mid-season topdressing N, but limited on basal N. A clearer understanding of the basal N fate under split fertilization is crucial for determining rational basal N split ratio to improve the yield and reduce the loss to environment. A two-year field experiment with two N rates of 150 and 300 kg Nha^(-1), two split ratios of basal N, 40% and 25%, and two rice varieties,Wuyunjing 23(japonica) and Y-liangyou 2(super hybrid indica), was conducted. Labelled ^(15) N urea was supplied in micro-plots as basal fertilizer to determine the plant uptake, translocation, soil residual, and loss of basal N fertilizer. The results showed that basal N absorbed by rice was only 1.6%–11.5% before tillering fertilization(8–10 d after transplanting), 6.5%–21.4% from tillering fertilization to panicle fertilization, and little(0.1%–4.4%) after panicle fertilization. The recovery efficiency of basal N for the entire rice growth stage was low and ranged from 18.7% to 24.8%, not significantly affected by cultivars or N treatments. Soil residual basal N accounted for 10.3%–36.4% and decreased with increasing total N rate and basal N ratio, regardless of variety and year. 43.8%–70.4% of basal N was lost into the environment based on the N balance. Basal N loss was significantly linearly positive related with the basal N rate and obviously enhanced by the increasing basal N ratio for both varieties in both 2012 and 2013. The N use efficiency and yield was significantly improved when decreasing the basal N ratio from 40% to 25%. The results indicated that the basal N ratio should be reduced, especially with limited N inputs, to improve the yield and reduce the N loss to the environment.展开更多
The Brazil nut tree（Bertholletia excelsa） is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground bioma...The Brazil nut tree（Bertholletia excelsa） is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground biomass production（kg dry weight）,nutrient uptake and requirements（N,P,Ca,Mg,K） of Brazil nut trees of different sizes grown under agroforestry conditions and fertilized at different levels.Eight of 70 experimental trees with different size were harvested and stem,branches and leaves were separated.Nutrient contents were determined for three trees of varying size.Average tree growth was fast,but variability was high,suggesting considerable potential for the improvement of this economically important species.The trees responded to increased levels of fertilizer and lime with significantly increased foliar nutrient contents and growth,probably because of the improved availability of Mg and Ca for which the species seems to have a relatively high demand.In contrast to Brazil nut trees grown in forest or dense plantations,the agroforestry trees invested a substantial part of their biomass and nutrients in large branches and developed spreading crowns.To improve stem form,reduce competition with associated crops for light and recycle nutrients,regular pruning of lower branches or planting arrangements that favor self-pruning are recommended.These measures would also increase the recycling of Ca and Mg,large quantities of which are contained in the branches.展开更多
基金Supported by the Project of Nanzhou Tobacco Company of Guizhou Province(201130)~~
文摘[Objective] The research aimed to provide the reference for the precise formula and balanced fertilization of tobacco production in Fuquan City, Guizhou Province. [Method] 180 soil samples were gathered from Fuquan City by Global Position System （GPS） fixed position. The main nutrient contents and pH value were analyzed. [Result] The average contents of organic matter, available nitrogen, available phosphorus, available potassium in tobacco planting soil were 26.8 g/kg, 134.1 mg/kg, 35.9 mg/kg, and 222.1 mg/kg respectively, and the coefficient of vari- ation were 25.8%, 21.4%, 72.1%, and 55.3% respectively. The pH value of tobacco planting soil was 6.2, and the pH value coefficient of variation was 15.3%. [Conclu. sien] The organic matter, available nitrogen, available phosphorus, available potassi- um contents were abundant in the mass, but there were big difference among dif- ferent towns. The precise fertility types and precise fertility dosage should be deter- mined according to the main nutdent state and pH value of tobacco planting soil in Fuquan city.
基金Supported by National Natural Science Foundation of China(30700563)the Middleaged Fund in Qinghai University(2009-QN-07)~~
文摘[Objective]The aim of this study is to explore the effects of grassland degradation on soil physical and chemical properties.[Method]The ratio of plant root to soil and soil texture on Alpine Meadow were investigated in this study,and soil available N,P,K,Cu,Zn,organic matter and pH value were also analyzed by routine analysis of soil nutrients in different degraded grasslands.[Result]With the intensification of degraded gradient and the soil depth,the ratio of plant root to soil was decreased gradually.The highest ratio of plant root to soil was in 0-10 cm depth of soil in grassland with different degraded gradients,while its ratio of plant root to soil changed from 0.001 to 0.040 with soil type of loam.Soil chemical characteristic changed in different degraded gradients.The content of available N,P,K reduced significantly with the soil depth and the intensification of degraded gradients.The content of Cu and Zn was relatively lack in degraded grassland.[Conclusion]There is no significant correlation between nutrition content or pH value and the succession degree of degraded grassland.
文摘In order to find out the main nutrient content of tobacco planting soil and the changing characteristics of tobacco quality in Linli County,the sampling survey data of tobacco planting soil samples in Linli in 2000 and 2015,and the main chemical components,appearances and sensory qualities and physical indexes of B2F and C3F tobacco leaves from 2000 to 2015 were comprehensively analyzed and evaluated.The results showed that:the available phosphorus increased by 6.10%per year and the pH value of tobacco planting soil increased in a small range year by year,the organic matter content decreased year by year,the alkali hydrolyzable nitrogen showed a downward trend,and the water-soluble chlorine showed a rapid downward trend;the soil fertility index(SFI)was at the"high"level;in 2000—2015,the quality of tobacco leaf was relatively stable and the quality was good.In Linli tobacco planting area,the application of nitrogen control,phosphorus reduction and chlorine supplement and increase of organic matter could help us achieve the goal of high quality and efficiency of tobacco production.
基金supported by the National Natural Science Foundation of China (No. 41501264)the Natural Science Foundation of Jiangsu Province, China (No. BK20140991)the Research Fund of State Key Laboratory of Soil and Sustainable Agriculture, Nanjing Institute of Soil Science, Chinese Academy of Sciences (No. Y412201441)
文摘There is an increasing concern that the continuous use of chemical fertilizers might lead to harmful effects on soil ecosystem.Accordingly, a biocompatible approach involving inoculation of beneficial microorganisms is presented to promote plant growth and simultaneously minimize the negative effect of chemical fertilizers. In this study, Rhodopseudomonas palustris, a plant growth-promoting rhizobacterium(PGPR), was inoculated into both fertilized and unfertilized soils to assess its influence on Stevia rebaudiana plant growth and microbial community in rhizosphere soils in a 122-d field experiment. Soil enzyme assays(dehydrogenase, urease, invertase, and phosphomonoesterase), real-time quantitative polymerase chain reaction(RT-_qPCR), and a high-throughput sequencing technique were employed to determine the microbial activity and characterize the bacterial community. Results showed that the R.palustris inoculation did not significantly influence Stevia yields and root biomass in either the fertilized or unfertilized soil. Chemical fertilization had strong negative effects on soil bacterial community properties, especially on dehydrogenase and urease activities.However, R. palustris inoculation counteracted the effect of chemical fertilizer on dehydrogenase and urease activities, and increased the abundances of some bacterial lineages(including Bacteroidia, Nitrospirae, Planctomycetacia, Myxococcales, and Legionellales). In contrast, inoculation into the unfertilized soil did not significantly change the soil enzyme activities or the soil bacterial community structure. For both the fertilized and unfertilized soils, R. palustris inoculation decreased the relative abundances of some bacterial lineages possessing photosynthetic ability, such as Cyanobacteria, Rhodobacter, Sphingomonadales, and Burkholderiales. Taken together, our observations stress the potential utilization of R. palustris as PGPR in agriculture, which might further ameliorate the soil microbial properties in the long run.
基金Under the auspices of Excellent Young Scholars of Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.DLSYQ 13004)Chinese Academy of Sciences/State Administration of Foreign Experts Affairs International Partnership Program for Creative Research Teams(No.KZZD-EW-TZ-07-09)Strategic Priority Research Program of Chinese Academy of Sciences(No.KFZD-SW-302-03)
文摘Urban forest soil infiltration, affected by various factors, is closely related with surface runoff. This paper studied the effect of urban forest types, vegetation configuration and soil properties on soil infiltration. In our study, 191 typical plots were sampled in Changchun City, China to investigate the soil infiltration characteristics of urban forest and its influencing factors. Our results showed that the steady infiltration rates of urban forest soil were highly variable. High variations in the final infiltration rates were observed for different vegetation patterns and compaction degrees. Trees with shrubs and grasses had the highest infiltration rate and trees with bare land had the lowest infiltration rate. In addition, our results showed that the soil infiltration rate decreased with an increase in the bulk density and with a reduction in the soil organic matter content and non-capillary porosity. The soil infiltration rate also had significantly positive relationships with the total porosity and saturated soil water content. Urban soil compaction contributed to low soil infiltration rates. To increase the infiltration rate and water storage volume of urban forest soil, proper techniques to minimize and mitigate soil compaction should be used. These findings can provide useful information for urban planners about how to maximize the water volume of urban forest soil and decrease urban instantaneous flooding.
文摘Limited availability of organic matter is a problem to sustain crop growth on sodic soil. Organic soil amendments are a costeffective source of nutrients to enhance crop growth. A field study was conducted to evaluate the effect of an organic soil amendment bioaugmented with plant growth-promoting fungi(SF_(OA) ) in combination with gypsum on soil properties and growth and yield attributes of Withania somnifera, one of the most valuable crops of the traditional medicinal system in the world, on a sodic soil at the Aurawan Research Farm of CSIR-National Botanical Research Institute, Lucknow, India. The SF_(OA) used was prepared by pre-enriching farm waste vermicompost with plant growth-promoting fungi before mixing with pressmud and Azadirachta indica seed cake. The application of SF_(OA) at 10 Mg ha^(-1)after gypsum(25.0 Mg ha^(-1)) treatment significantly(P < 0.05) increased root length(by 96%) and biomass(by 125%) of Withania plants compared to the control without SF_(OA) and gypsum. Similarly, the highest withanolide contents were observed in leaves and roots of Withania plants under 10 Mg ha^(-1)SF_(OA) and gypsum. Combined application of SF_(OA) and gypsum also improved physical, chemical and enzymatic properties of the soil, with the soil bulk density decreasing by 25%, water-holding capacity increasing by 121%, total organic C increasing by 90%, p H decreasing by 17% and alkaline phosphatase, β-glucosidase, dehydrogenase and cellulase activities increasing by 54%, 128%, 81% and 96%, respectively, compared to those of the control. These showed that application of the SF_(OA) tested in this study might reclaim sodic soil and further support Withania cultivation and results were better when the SF_(OA) was applied after gypsum treatment.
基金Under the auspices of National Natural Science Foundation of China(No.41361015,41271106,41271107,41501105)Open Fund of the State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration,Northeast Normal University(No.130028630)
文摘Hydrology plays a dominant role in wetland plant distribution and microbial composition, but few studies explicitly attempted to relate the linkage between wetland vegetation and microbial community. The present study consisted of five wetland plant communities along three adjacent flood gradients zones(zone 1 dominated by Carex appendiculat, zone 2 dominated by Eleocharis ovate, and zone 3 dominated by Phragmites australis/Bidens pilosa/Calamagrostis angustifolia, which formed separate, monoculture patches). Gram negative and arbuscular mycorrhizal fungal phospholipid fatty acid(PLFA) are more abundant in the site with short flooding period(zone 3) than in the site with long flooding period(zone 1), and they are also different in the P. australis, B. spilosa and C. angustifolia of zone 3. Principle Component Analysis(PCA) showed that the flooding period could explain 92.4% of variance in microbial composition. Redundancy Analysis(RDA) showed that available nitrogen(AN), total nitrogen(TN) and soil organic matter(SOM) could explain the 79.5% of variance in microbial composition among E. ovata, P. australis, B. pilosa and C. angustifolia. Results demonstrated that flooding period was the main factor in driving the microbial composition and plant-derived resources could influence soil microbial composition in the seasonally flooded zones.
基金Under the auspices of the National Key R&D Program of China(No.2017YFC0505906)the National Natural Science Foundation of China(No.51639001,51379012)the Interdiscipline Research Funds of Beijing Normal University
文摘Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.
基金funding provided by Universitàdegli Studi della Campania Luigi Vanvitelli within the CRUI-CARE Agreement。
文摘Both climate and land-use changes,including the introduction and spread of allochthonous species,are forecast to affect forest ecosystems.Accordingly,forests will be affected in terms of species composition as well as their soil chemical and biological characteristics.The possible changes in both tree cover and soil system might impact the amount of carbon that is stored in living plants and dead biomass and within the soil itself.Additionally,such alterations can have a strong impact on the detrital food web that is linked to litter decomposition.Although there are studies on the infuence of plant diversity on soil physical and chemical characteristics,the effects on soil biological activity and carbon storage processes remain largely unknown.The aim of this study was to investigate and compare chemical and biological variables in covariation with plant communities in an autochthonous beech forest(Fagus sylvatica L.)and a black pine plantation(Pinus nigra J.F.Arnold subsp.nigra).Our results confirmed that the two communities were considerably different,with the old-growth beech community having a lower number of plant species and the pine community was in development as a consequence of anthropogenic activities.These aspects of the two communities were also refected in the soil,with the beech soil having higher nitrogen levels and a more specialized microbial community compared to the pine soil,with most extracellular enzymes(such as peroxidase and chitinase)showing lower activity in the pine soil.
基金financially supported by the National Natural Science Foundation of China (31260125,31000214)
文摘Grazing can modulate the feedback between vegetation and soil nutrient dynamics（carbon and nitrogen）,altering the cycles of these elements in grassland ecosystems.For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia,China,we examined the plant biomass,SOC（soil organic carbon）,total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites.Significantly lower aboveground biomass,root biomass,litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site,with decreases of 42.0%,16.2%,59.4% and 30.0%,respectively.The effects of grazing on plant carbon,nitrogen,？15N and ？13C values were uniform among species.The levels of plant carbon and nitrogen in grasses were greater than those in the forbs（except for the carbon of Cynanchum komarovii and Euphorbia esula）.Root 15 N and 13 C values increased with grazing,while the responses of root carbon and nitrogen to grazing showed no consistent patterns.Root 15 N and 13 C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site,respectively.The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths（0–10 and 10–20 cm）,and values of SOC and total N at the surface（0–10 cm） were lower than those in the deeper soils（10–20 cm）.Soil ？15N values were not affected by grazing at any sampling depth,whereas soil ？13C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0–10 and 10–20 cm,respectively.The soil ？13C values（–8.3‰ to –6.7‰） were higher than those for roots（–20.2‰ to –15.6‰） and plant tissues（–27.9‰ to –13.3‰）.Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.
基金funded by Innovate UK(100867)with matching funding from several commercial companiesthe financial assistance of the China Scholarship Council(201306300133 and 201506300012)
文摘Studies were conducted to identify candidate soil microbes responsible for observed differences in strawberry vigour at a small spatial scale, which was not associated with visual disease symptoms. Samples were obtained from the soils close to the rhizosphere of ‘big＇ and ‘small＇ plants from small plots which exhibited large local heterogeneity in plant vigour. A metabarcoding approach was used to profile bacterial and fungal compositions, using two primer pairs for 16 S ribosomal RNA genes（16S r DNA） and one for the fungal internal transcribed spacer（ITS） region. Of the two 16 S r DNA primer sets, the 341F/805 R resulted in sequences of better quality. A total 28 operational taxonomic units（OTUs） had differential relative abundance between samples from ‘big＇ and ‘small＇ plants. However, plausible biological explanation was only possible for three fungal OTUs. Two were possible phytopathogens： Verticillium spp. and Alternaria alternata although the latter has never been considered as a main pathogen of strawberry in the UK. For samples from ‘small＇ plants, the abundance of these OTUs was much greater than from ‘big＇ plants. The opposite was true for a mycorrhizal OTU. These results suggest that soil microbes related to crop production can be identified using metabarcoding technique. Further research is needed to assess whether A. alternata and Verticillium spp. could affect strawberry growth in the field.
基金This study was financially supported by the National Natural Science Foundation of China(41601221)the Ministry of Science and Technology of China(2016YFC0501605)+2 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(2019052)the Bingwei Outstanding Young Talent Project from the Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences(2017RC203)the Scientific Research Program from the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources(A314021402-2010)。
文摘Soil water deficit is increasingly threatening the sustainable vegetation restoration and ecological construction on the Loess Plateau of China due to the climate warming and human activities.To determine the response thresholds of Amygdalus pedunculata(AP)and Salix psammophila(SP)to soil water availability under different textural soils,we measured the changes in net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),leaf water potential(ψw),water use efficiency(WUE)and daily transpiration rate(Td)of the two plant species during soil water content(SWC)decreased from 100%field capacity(FC)to 20%FC in the sandy and loamy soils on the Loess Plateau in the growing season from June to August in 2018.Results showed that Pn,Gs,WUE and Td of AP and SP remained relatively constant at the beginning of soil water deficit but decreased rapidly as plant available soil water content(PASWC)fell below the threshold values in both the sandy and loamy soils.The PASWC thresholds corresponding to Pn,Gs and Ci of AP in the loamy soil(0.61,0.62 and 0.70,respectively)were lower than those in the sandy soil(0.70,0.63 and 0.75,respectively),whereas the PASWC thresholds corresponding to Pn,Gs and Ci of SP in the loamy soil(0.63,0.68 and 0.78,respectively)were higher than those in the sandy soil(0.58,0.62 and 0.66,respectively).In addition,the PASWC thresholds in relation to Td and WUE of AP(0.60 and 0.58,respectively)and SP(0.62 and 0.60,respectively)in the loamy soil were higher than the corresponding PASWC thresholds of AP(0.58 and 0.52,respectively)and SP(0.55 and 0.56,respectively)in the sandy soil.Furthermore,the PASWC thresholds for the instantaneous gas exchange parameters(e.g.,Pn and Gs)at the transient scale were higher than the thresholds for the parameters(e.g.,Td)at the daily scale.Our study demonstrates that different plant species and/or different physiological parameters exhibit different thresholds of PASWC and that the thresholds are affected by soil texture.The result can provide guidance for the rational allocation and sustainable management of reforestation species under different soil conditions in the loess regions.
基金WetlandInnovationItemofChineseAcademyofSciences (No .ZKHZ 3 0 6 )
文摘The characteristics of vertical and horizontal variations of lead element(Pb) in soil plant system of vertical zone in Changbai Mountain National Nature Reserve(CNNR) were studied. The results showed that Pb concentrations in soils of vertical zone are all above 25 mg/kg, and the average Pb concentration of each soil zone negatively correlates its degree of variation, i.e. brown coniferous forest soil zone has the lowest average Pb concentration of four soil zones, and the highest horizontal variation; however, mountain soddy forest soil has the highest average Pb concentration, and the lowest horizontal variation; the average concentration of plant Pb of each plant zone is lower than the worldwide average level of Pb in plant(Clarke), respectively, and plant Pb content order is consistent with soil Pb content order, but their horizontal variations are different from those in soil zones, the variation of mountain tundra forest zone is highest, but Betula ermanii forest zone the lowest. Vertical variation of plant Pb is obviously higher than that in soils with variation coefficient of 89.76%; the enrichment capability of plant for Pb is depended on the plant types and the different organs of plant; parent material and parent rock, pH values, soil organic matter and soil particle fraction etc. are the main factors influencing variations of Pb content in soil plant system of vertical zone in CNNR.
基金This study was supported by the National Natural Science Foundation of China(No.31971453)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and Postgraduate Research&Practice Innovation Program of Jiangsu Province.
文摘Nitrogen is an essential component in forest ecosystem nutrient cycling.Nitrogen fractions,such as dissolved nitrogen,ammonium,nitrate,and microbial biomass nitrogen,are sensitive indicators of soil nitrogen pools which affect soil fertility and nutrient cycling.However,the responses of nitrogen fractions in forest soils to organic mulching are less well understood.The rhizosphere is an important micro-region that must be considered to better understand element cycling between plants and the soil.A field investigation was carried out on the effect of mulching soil in a 15-year-old Ligustrum lucidum urban plantation.Changes in total nitrogen and nitrogen fractions in rhizosphere and bulk soil in the topsoil(upper 20 cm)and in the subsoil(20-40 cm)were evaluated following different levels of mulching,in addition to nitrogen contents in fine roots,leaves,and organic mulch.The relationships between nitrogen fractions and other measured variables were analysed.Organic mulching had no significant effect on most nitrogen fractions except for the rhizosphere microbial biomass nitrogen(MBN),and the thinnest(5 cm)mulching layer showed greater effects than other treatments.Rhizosphere MBN was more sensitive to mulching compared to bulk soil,and was more affected by soil environmental changes.Season and soil depth had more pronounced effects on nitrogen fractions than mulching.Total nitrogen and dissolved nitrogen were correlated to soil phosphorus,whereas other nitrogen fractions were strongly affected by soil physical properties(temperature,water content,bulk density).Mulching also decreased leaf nitrogen content,which was more related to soil nitrogen fractions(except for MBN)than nitrogen contents in either fine roots or organic mulch.Frequent applications of small quantities of organic mulch contribute to nitrogen transformation and utilization in urban forests.
基金supported in part by the National Basic Research Program of China (2009CB421303)supported by National Natural Science Foundation of China (30970546)
文摘Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.
文摘Deserts have traditionally been considered as a low moisture system where biological activity is triggered by unpredictable rainfall in time and space. Studies on desert ecosystems functions, processes, dynamics and diversity of soil biota had been found to contribute to understanding of their role in primary production and management of soil ecosystems. As belowground biota is very diverse they are playing an important role in above as well below ground essential ecosystem processes e.g. primary production, decomposition, nutrient mineralization etc. The challenge is to use the emerging knowledge of soil biota diversity in understanding basic ecosystems function.
基金the Spanish Agency of Cooperation and Development (AECID)
文摘Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna(Vicugna vicugna) and alpaca(Lama pacos). The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined: total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.
基金Project supported by the National Natural Science Foundation of China (Nos. 30390080 and 30370287)the Ministry of Education, Science and Technology, Germany.
文摘A field experiment with a split-plot design was carried out at Dongbeiwang Farm in Beijing Municipality to establish reliable N fertilizer recommendation indices for summer maize (Zea mays L.) in northern China using the soil Nmin (mineral N) test as well as the plant nitrate and SPAD (portable chlorophyll meter readings) tests. The results showed that Nmin sollwert (NS) 60 kg N ha-1 at the third leaf stage and N rate of 40 to 120 kg N ha-1 at the tenth leaf stage could meet the N requirement of summer maiz…
基金financially supported by the National Natural Science Foundation of China (No. 41171235)Jiangsu Agriculture Science and Technology Innovation Fund, China (No. CX(13)3040)the Special Fund for Environmental Research in the Public Interest, China (No. 201309035-7)
文摘Split fertilization strategy is popularly adopted in rice to synchronize soil nitrogen(N) supply and crop N demand. Attention has been paid more on mid-season topdressing N, but limited on basal N. A clearer understanding of the basal N fate under split fertilization is crucial for determining rational basal N split ratio to improve the yield and reduce the loss to environment. A two-year field experiment with two N rates of 150 and 300 kg Nha^(-1), two split ratios of basal N, 40% and 25%, and two rice varieties,Wuyunjing 23(japonica) and Y-liangyou 2(super hybrid indica), was conducted. Labelled ^(15) N urea was supplied in micro-plots as basal fertilizer to determine the plant uptake, translocation, soil residual, and loss of basal N fertilizer. The results showed that basal N absorbed by rice was only 1.6%–11.5% before tillering fertilization(8–10 d after transplanting), 6.5%–21.4% from tillering fertilization to panicle fertilization, and little(0.1%–4.4%) after panicle fertilization. The recovery efficiency of basal N for the entire rice growth stage was low and ranged from 18.7% to 24.8%, not significantly affected by cultivars or N treatments. Soil residual basal N accounted for 10.3%–36.4% and decreased with increasing total N rate and basal N ratio, regardless of variety and year. 43.8%–70.4% of basal N was lost into the environment based on the N balance. Basal N loss was significantly linearly positive related with the basal N rate and obviously enhanced by the increasing basal N ratio for both varieties in both 2012 and 2013. The N use efficiency and yield was significantly improved when decreasing the basal N ratio from 40% to 25%. The results indicated that the basal N ratio should be reduced, especially with limited N inputs, to improve the yield and reduce the N loss to the environment.
基金funded by the German Ministry of Education and Research(BMBF)the Brazilian Conselho National de Desenvolvimento Científico e Tecnológico(CNPq)
文摘The Brazil nut tree（Bertholletia excelsa） is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground biomass production（kg dry weight）,nutrient uptake and requirements（N,P,Ca,Mg,K） of Brazil nut trees of different sizes grown under agroforestry conditions and fertilized at different levels.Eight of 70 experimental trees with different size were harvested and stem,branches and leaves were separated.Nutrient contents were determined for three trees of varying size.Average tree growth was fast,but variability was high,suggesting considerable potential for the improvement of this economically important species.The trees responded to increased levels of fertilizer and lime with significantly increased foliar nutrient contents and growth,probably because of the improved availability of Mg and Ca for which the species seems to have a relatively high demand.In contrast to Brazil nut trees grown in forest or dense plantations,the agroforestry trees invested a substantial part of their biomass and nutrients in large branches and developed spreading crowns.To improve stem form,reduce competition with associated crops for light and recycle nutrients,regular pruning of lower branches or planting arrangements that favor self-pruning are recommended.These measures would also increase the recycling of Ca and Mg,large quantities of which are contained in the branches.
