Eco-geographic regional system is formed by division or combination of natural features based on geographic relativity and comparison of major ecosystem factors(including biological and non-biological) and geographic ...Eco-geographic regional system is formed by division or combination of natural features based on geographic relativity and comparison of major ecosystem factors(including biological and non-biological) and geographic zonality.In previous studies, soil types were often taken as a basis for soil regionalization.However, the quantitative characteristics of soil indicators are fitter than the qualitative ones of soil types for modern regionalization researches.Based on the second China's national soil survey data and the provincial soil resource information, by principal analysis and discriminant analysis, this paper discusses the appropriate soil indicators as the complement of eco-geographic region indicator systems and the relationships between these soil indicators and soil types in regionalization.The results show that five indicators are used in eco-geographic zonality in mid-temperate zone of eastern China which are organic matter content, cation exchange capacity, pH, clay content and bulk density in topsoils.With a regression-kriging approach, the maps of soil indicators in mid-temperate zone of eastern China are compiled with a resolution of 1 km in every grid and the indicative meanings of these soil indicators are discussed.By cluster analysis it is proved that these soil indicators are better than the soil types and soil regionalization in delineating eco-geographic regions.展开更多
Assessing soil quality is essential for crop management and soil temporal changes. The present study aims to evaluate soil quality in the Ferralitic soils context countrywide. This assessment was done using multivaria...Assessing soil quality is essential for crop management and soil temporal changes. The present study aims to evaluate soil quality in the Ferralitic soils context countrywide. This assessment was done using multivariate soil quality indice (SQI) models, such as additive quality index (AQI), weighted quality indexes (WQI<sub>add</sub> and WQI<sub>com</sub>) and Nemoro quality index (NQI), applied to two approaches of indicator selection: total data set (TDS) and minimum data set (MDS). Physical and chemical soil indicators were extracted from the ORSTOM’s reports resulting from a sampling campaign in different provinces of Gabon. The TDS approach shows soil quality status according to eleven soil indicators extracted from the analysis of 1,059 samples from arable soil layer (0 - 30 cm depth). The results indicated that 87% of all provinces presented a very low soil quality (Q5) whatever the model. Among soil indicators, exchangeable K<sup>+</sup> and Mg<sup>2+</sup>, bulk density and C/N ratio were retained in MDS, using principal component analysis (PCA). In the MDS approach, 50 to 63% of provinces had low soil quality grades with AQI, WQI<sub>add</sub> and NQI, whereas the total was observed with WQI<sub>com</sub>. Only 25% of provinces had medium soil quality grades with AQI and NQI models, while 12.5% (NQI) and 25% (AQI) presented high quality grades. Robust statistical analyses confirmed the accuracy and validation (0.80 r P ≤ 0.016) of AQI, WQI<sub>add</sub> and NQI into the TDS and MDS approaches. The same sensitivity index value (1.53) was obtained with AQI and WQI<sub>add</sub>. However, WQI<sub>add</sub> was chosen as the best SQI model, according to its high linear regression value (R<sup>2</sup> = 0.82) between TDS and MDS. This study has important implications in decision-making on monitoring, evaluation and sustainable management of Gabonese soils in a pedoclimatic context unfavorable to plant growth.展开更多
The estuary tides affect groundwater dynamics;these areas are susceptible to waterlogging and salinity issues.A study was conducted on two fields with a total area of 60 hectares under a center pivot irrigation system...The estuary tides affect groundwater dynamics;these areas are susceptible to waterlogging and salinity issues.A study was conducted on two fields with a total area of 60 hectares under a center pivot irrigation system that works with solar energy and belong to a commercial farm located in Northern Sudan.To monitor soil salinity and calcium carbonate in the area and stop future degradation of soil resources,easy,non-intrusive,and practical procedures are required.The objective of this study was to use remote sensing-determined Sentinel-2 satellite imagery using various soil indices to develop prediction models for the estimation of soil electrical conductivity(EC)and soil calcium carbonate(CaCO_(3)).Geo-referenced soil samples were collected from 72 locations and analyzed in the laboratory for soil EC and CaCO_(3).The electrical conductivity of the soil saturation paste extract was represented by average values in soil dataset samples from two fields collected from the topsoil layer(0 to 15 cm)characteristic of the local salinity gradient.The various soil indices,used in this study,were calculated from the Sentinel-2 satellite imagery.The prediction was determined using the root mean square error(RMSE)and cross validation was done using coefficient of determination.The results of regression analysis showed linear relationships with significant correlation between the EC analyzed in laboratory and the salinity index-2“SI2”(Model-1:R^(2)=0.59,p=0.00019 and root mean square error(RMSE=1.32%)and the bare soil index“BSI”(Model-2:R^(2)=0.63,p=0.00012 and RMSE=6.42%).Model-1 demonstrated the best model for predicting soil EC,and validation R^(2)and RMSE values of 0.48%and 1.32%,respectively.The regression analysis results for soil CaCO_(3)determination showed linear relationships with data obtained in laboratory and the bare soil index“BSI”(Model-3:R^(2)=0.45,p=0.00021 and RMSE=1.29%)and the bare soil index“BSI”&Normalized difference salinity index“NDSI”(Model-4:R^(2)=0.53,p=0.00015 and RMSE=1.55%).The validation confirmed the Model-3 results for prediction of soil CaCO_(3)with R^(2)and RMSE values of 0.478%and 1.29%,respectively.Future soil monitoring programs might consider the use of remote sensing data for assessing soil salinity and CaCO_(3)using soil indices results generated from satellite image(i.e.,Sentinel-2).展开更多
The North China Plain（NCP） is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in r...The North China Plain（NCP） is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in relation to the grain yield for the winter wheat（Triticum aestivum L.）-maize（Zea mays L.） cropping system in a high-productivity farmland of the NCP. The field trials were conducted in three fields with different grain yield levels in Tai＇an City, Shandong Province, China, during the 2009–2012 period. Consistent field management strategies were applied in the three fields. Fifty-one physical and chemical indicators of the soil profile as related to grain yield were evaluated. An approximate maximum of 17.8% annual average grain yield difference was observed in the fields during the period of 2009–2012. The soil indicators were classified into three clusters with specific functions using cluster analysis, and three key indicators were extracted from each cluster to characterize the different soil properties of three fields. The first cluster represented soil water retention capacity, and the key indicator was available soil water（ASW）, which ranged from 153 to 187 mm in the 1.2 m profile and was correlated positively with grain yield. The second cluster represented soil water conductivity, as measured by saturated hydraulic conductivity（K s）. The higher yield field had a greater capacity to retain topsoil water for its lower K s（1.9 cm d^–1） in the 30–70 cm soil layer as compared to the lower yield field. The third cluster represented nutrient storage and supply, as indicated by the ratio of nutrient content to silt＋clay content of the top soil layer. The ratio of soil organic matter（OM）, total nitrogen（TN）, available P, exchangeable K＋ to silt＋clay content in the 0–20 cm soil layer were 19.0 g kg^–1, 1.6 g kg^–1, 94.7 mg kg^–1, 174.3 mg kg^–1 in the higher yield field, respectively, and correlated positively with the grain yield. By characterizing the differences in soil properties among fields with different yield levels, this study offers the scientific basis for increasing grain yield potential by improving the soil conditions in the NCP.展开更多
Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2...Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil （0-15 cm） moisture availability were noted in soils under MPTs.展开更多
Tobacco-planting plays an important role in ensuring the high-quality tobacco raw materials supply and the local social and economic development in Chenzhou City. In recent years whether tobacco-planting is better for...Tobacco-planting plays an important role in ensuring the high-quality tobacco raw materials supply and the local social and economic development in Chenzhou City. In recent years whether tobacco-planting is better for the maintenance and improvement of soil fertility than other crop-planting has been highly concerned. In this study, 16 soil fertility indicators and soil integrated index (<em>IFI</em>) were compared by 21 pairs of fields in Chenzhou city under the rotations of tobacco-rice (TF) and rice-rice (RR), and results showed that, comparing the mean values of soil fertility indicators, the contents of OM, TN, AN, AK, S and <em>IFI</em> were extremely significantly higher in TR than those in RR (p < 0.01), the contents of Cu, Ca, Mg and Fe were significantly higher in TR than those in RR (p < 0.05), but Mn content was significantly lower in TR than those in RR (p < 0.05). Meanwhile the contents of TP, TK and AP were insignificantly higher in TR than those in RR, and the contents of B, Mo and Zn were insignificantly lower in TR than those in RR. The above significant differences in soil fertility indicators were mainly due to relatively higher fertilizer inputs and less nutrient removal during tobacco-growing season than during rape-growing season, the net increase of N, P<sub>2</sub>O<sub>5</sub> and K<sub>2</sub>O are 8.61, 5.25 and 24.89 kg per 667 m<sup>2</sup> respectively in tobacco-growing season, while the net decrease of N, P<sub>2</sub>O<sub>5 </sub>and K<sub>2</sub>O are 8.88, 4.70 and 4.62 kg per 667 m<sup>2</sup> respectively in rape-growing season. C.V. of soil fertility indicators and <em>IFI</em> were meanly lower in TR (52.25% and 15.95%, respectively) than those in RR (63.07% and 22.12%, respectively). Comparatively, tobacco-planting can improve soil fertility better than rape-planting when rotated with late rice in Chenzhou city. For tobacco-planting, Mg fertilizer should be applied for 23.8% TR fields, while more N, K, Ca, Mg, S and B fertilizers should be applied for 42.86%, 23.81%, 14.29%, 47.62%, 80.95% and 47.62% RR fields, respectively.展开更多
To evaluate the validity of different indices in estimating soil readily mineralizable N, soil microbial biomass （Nmic）, soil active N （SAN）, soluble organic N （SON）, net N mineralization rate （NNR） and gross ...To evaluate the validity of different indices in estimating soil readily mineralizable N, soil microbial biomass （Nmic）, soil active N （SAN）, soluble organic N （SON）, net N mineralization rate （NNR） and gross N mineralization rate （GNR） in mineral soils （0-10 cm） from six forest stands located in central Germany were determined and compared with two sampling times： April and November. Additionally, soil density fractionation was conducted for incubated soils （with addition of ^15NH4-N and glucose, 40 days） to observe the sink of added ^15N in different soil fractions. The study showed that Nmic and NNR in most stands differed significantly （P 〈 0.05） between the two sampling times, but not GNR, SAN and SON. In November, no close relationships were found between GNR and other N indices, or between Nrnic, SON, and SAN and forest type. However, in April, GNR was significantly correlated （P 〈 0.05） with Nmic, SAN, and NNR along with Nmlc under beech being significantly higher （P 〈 0.05） than under conifers. Furthermore, density fractionation revealed that the light fraction （LF, 0.063-2 mm, 〉 1.7 gcm^-3） was not correlated with the other N indices. In contrast, results from the incubation study proved that more 15N was incorporated into the heavy fraction （HF 〈 0.063 ram, 〉 1.7 g cm^-3） than into LF, indicaing that more labile N existed in HF than in LF. These findings suggested that attention should be paid to the differences existing in N status between agricultural and forest soils.展开更多
Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertili...Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertility survey methods are needed. This study aimed to test the applicability of infrared spectroscopy （IR） as a diagnostic screening tool for making soil fertility recommendations in small-scale production systems. Soil fertility survey of 150 small-scale groundnut farms in western Kenya was conducted using a spatially stratified random sampling strategy. Soil properties examined were pH in water （pHw）, total carbon （C）, total nitrogen （N）, extractable phosphorus （P）, exchangeable potassium （K）, calcium （Ca）, magnesium （Mg） and texture. These properties were calibrated to mid-infrared （MIR） diffuse reflectance using partial least square regression （PLSR）. Cross-validated coefficient of determination （r2） values obtained from calibration models were 〉 0.80 for all properties, except P and K with 0.66 and 0.50 respectively. Soil nutritional deficiencies were evaluated using critical nutrient limits based on IR predictions and composite soil fertility indices （SFIs） developed from the soil properties using principal component analysis. The SFIs were calibrated to MIR soil spectral reflectance with cross-validated r： values 〉 0.80. The survey showed that 56% of the groundnut farms had severe soil nutrient constraints for production, especially exchangeable Ca, available P and organic matter. IR can provide a robust tool for farm soil fertility assessment and recommendation systems when backed up by conventional reference analyses. However, further work is required to test direct calibration of crop responses to spectral indicators and to improve prediction of extractable P and K tests.展开更多
A study on community soil fertility management concepts and practices was conducted through rapid and participatory method of research in 15 villages of the Gourma region in Eastern part of Burkina Faso. These investi...A study on community soil fertility management concepts and practices was conducted through rapid and participatory method of research in 15 villages of the Gourma region in Eastern part of Burkina Faso. These investigations aimed at determining farmers＇ knowledge on soil resources： local soil taxonomy and indicators of soil degradation, soil fertility management practices, and capacity for adoption of new technologies in soil fertility management. The results of the study showed that the main parameter for soil classification for all the investigated villages was soil texture composition; soil degradation was evaluated according to crops yield decrease and the development Striga sp. in 100% of the investigated villages; the use of organic manure and long term fellow were the main practices for soil fertility management; concerning the villages where modem technologies of soil fertility management were introduced, the lack of tools and capacity building were the main limiting factors of the adoption of these improved practices at small scale farmers＇ level. Even if discordance between scientific and local soil taxonomy were revealed by our investigations; significant similarities between indigenous and scientific indices of soil degradation were noticed. With regard to the actual magnitude of soil degradation; the local techniques of soil fertility management need to be improved and accessible to a big number of farmers.展开更多
Awareness of how soil properties vary over agroecosystems(AES) is essential for understanding soil potentials and improving site-specific agricultural management strategies for a sustainable ecosystem. This study exam...Awareness of how soil properties vary over agroecosystems(AES) is essential for understanding soil potentials and improving site-specific agricultural management strategies for a sustainable ecosystem. This study examined the characteristics of soil quality attributes and implications for agriculture in the Choke Mountain watershed in Ethiopia. Forty-seven composite soil samples(0–20 cm deep) were collected from lowland and valley fragmented(AES 1),midland plain with black soil(AES 2), midland plain with brown soil(AES 3),sloppy midland land(AES 4), and hilly and mountainous highlands(AES 5).Ten of 15 soil quality properties were significant(P < 0.05 or 0.01), including silt, exchangeable bases, cation exchange capacity, percent base saturation,p H, organic matter, total nitrogen and available phosphorous(P) across the five AES. However, all properties were variable with coefficients of variation from 7%(total porosity) to 169%(available P) across the AES. Although AES 2and 3 are affected by waterlogging and acidity, these two have better prospects for agriculture, but AES 1, 4, and 5 are unsuitable for agriculture because of soil erosion. Therefore, appropriate and applicable soil management strategies, particularly lime application and organic fertilizer, are fundamental to reversing soil acidity and improving soil fertility.展开更多
Developments in soil biology and in methodsto characterize soil organic carbon can potentially delivernovel soil quality indicators that can help identifymanagement practices able to sustain soil productivityand envir...Developments in soil biology and in methodsto characterize soil organic carbon can potentially delivernovel soil quality indicators that can help identifymanagement practices able to sustain soil productivityand environmental resilience. This work aimed atsynthesizing results regarding the suitability of a range ofsoil biological and biochemical properties as novel soilquality indicators for agricultural management. The soilproperties, selected through a published literature review,comprised different labile organic carbon fractions [hydrophilicdissolved organic carbon, dissolved organic carbon,permanganate oxidizable carbon (POXC), hot waterextractable carbon and particulate organic matter carbon],soil disease suppressiveness measured using a Pythium-Lepidium bioassay, nematode communities characterizedby amplicon sequencing and qPCR, and microbialcommunity level physiological profiling measured withMicroResp™. Prior studies tested the sensitivity of each ofthe novel indicators to tillage and organic matter additionin ten European long-term field experiments (LTEs) andassessed their relationships with pre-existing soil qualityindicators of soil functioning. Here, the results of theseprevious studies are brought together and interpretedrelative to each other and to the broader body of literatureon soil quality assessment. Reduced tillage increasedcarbon availability, disease suppressiveness, nematoderichness and diversity, the stability and maturity of thefood web, and microbial activity and functional diversity.Organic matter addition played a weaker role in enhancingsoil quality, possibly due to the range of composition of theorganic matter inputs used in the LTEs. POXC was theindicator that discriminated best between soil managementpractices, followed by nematode indices based on functionalcharacteristics. Structural equation modeling showsthat POXC has a central role in nutrient retention/supply,carbon sequestration, biodiversity conservation, erosion control and disease regulation/suppression. The novelindicators proposed here have great potential to improveexisting soil quality assessment schemes. Their feasibilityof application is discussed and needs for future research are outlined.展开更多
Vegetation fractional coverage （VFC） is an important index to describe and evaluate the ecological system. The vegetation index is widely used to monitor vegetation coverage in the field of remote sensing （RS）. In...Vegetation fractional coverage （VFC） is an important index to describe and evaluate the ecological system. The vegetation index is widely used to monitor vegetation coverage in the field of remote sensing （RS）. In this paper, the author conducted a case study of the delta oasis of Weigan and Kuqa rivers, which is a typical saline area in the Tarim River Watershed. The current study was based on the TM/ETM＋ images of 1989, 2001, and 2006, and supported by Geographic Information System （GIS） spatial analysis, vegetation index, and dimidiate pixel model. In addition, VBSl （vegetation, bare soil and shadow indices） suitable for TM/ETM＋ irrlages, constructed with FCD （forest canopy density） model principle and put forward by ITTO （International Tropical Timber Organization）, was used, and it was applied to estimate the VFC. The estimation accuracy was later prow^n to be up to 83.52%. Further, the study analyzed and appraised the changes in vegetation patterns and revealed a pattern of spatial change in the vegetation coverage of the study area by producing the map of VFC levels in the delta oasis. Forest, grassland, and farmland were the three main land-use types with high and extremely-high coverage, and they played an important role in maintaining the vegetation. The forest area determined the changes of the coverage area, whereas the other two land types affected the directions of change. Therefore, planting trees, protecting grasslands, reclaiming farmlands, and controlling unused lands should be included in a long-term program because of their importance in keeping regional vegetation coverage. Finally, the dynamic variation of VFC in the study area was evaluated according to the quantity and spatial distribution rendered by plant cover diigital images to deeply analyze the reason behind the variation.展开更多
This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The nor...This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The northern part of the Shaanxi province in China was taken as a case. Multi-temporal remotely sensed materials of both Landsat TM and thematic maps （ETM＋） were used as the bases to provide comprehensive views of surface conditions such as vegetation cover and salinization detection. With ERDAS ver. 9.1 software, the Normalized Differential Salinity Index （NDSl） and Salinity Index （S.I.） were computed and then evaluated for land degradation by salinization. Arc/Info ver. 9.2 software was used along with field observation data （GPS） for analysis. Using spatial analysis methods, results showed that 19 973.1 km^2 （72%） of land had no risk of land degradation by salinization, 3 684.7 km^2 （13%） had slight land degradation by salinization risk, 2 797.9 km^2 （10%） had moderate land degradation by salinization risk, and 1 218.9 km^2 （4%） of the total land area was at a high risk of land degradation by salinization. The study area, in general, is exposed to a high risk of soil salinization.展开更多
Soil cleaning, the ability of the soil to immobilize the risk elements, belongs to important agroecosystem services in terms of protection of the hydrosphere and plant production from contamination. Dynamic monitoring...Soil cleaning, the ability of the soil to immobilize the risk elements, belongs to important agroecosystem services in terms of protection of the hydrosphere and plant production from contamination. Dynamic monitoring of selected indicators of soil quality was realized in a special network of site on soil used for planting fast growing willow (Salix viminalis). Monitoring of the study site Kuchyňa (Mollic Fluvisol) is running since 2010 year. The fast-growing willow was planted on an area of about 43 hectares. Study site Kuchyňa belonged to the degraded contaminated sites, at the time of planting (the total contents of the risk elements were as follows: Cd 1.016 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, Zn 199.000 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, Ni 51.500 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>) There were positive changes in the total content of cadmium, zinc and nickel (in 2018 year), the zinc content decreased by 27% compared to 2010, the nickel content was lower by 23% and the Cd content by 57% in comparison to 2010 year, these elements have a declining trend during the monitored period. The remediation ability of the willow in relation to the risk elements was manifested by the accumulation of these elements in the wood mass and by their decrease in the soil below the limit value. The regulatory ecosystem service, the potential for the immobilisation of the risk elements, was evaluated based on the sum of the assessment of the contamination potential and the sorption potential of soil. The decrease of the total content of risk elements in the soil below the limit value was manifested in the increase of the potential of the agroecosystem regulatory service, the potential of risk element immobilisation, from very low category to medium category. If willow cultivation continued in the next decade, the value of risk element Zn would most likely reach the value 73 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, which is less than 50% of the limit value, based on the results of the predictive model. In the case of Cd, the soil would be completely cleaned and in the case of Ni, its total content in the soil would fall to 23 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, which is less than 40% of the limit value. The overall potential for contamination would fall into the category—very low (forecast for 2021 year). The higher potential of immobilisation reduces the risk of contaminants transport and thus prevents contamination of the other ecosystem components such as biota.展开更多
The labile organic carbon(C)and C-related enzymes are sensitive indicators capturing alterations of soil organic matter(SOM),even in a short-time scale.Although the effects of crop husbandry and land use change on the...The labile organic carbon(C)and C-related enzymes are sensitive indicators capturing alterations of soil organic matter(SOM),even in a short-time scale.Although the effects of crop husbandry and land use change on these attributes have been well studied,there is no consensus about how plant phenology may impact them.This study aimed to determine the short-term effect o f six distinct phenological stages(PS-1:full bloom;PS-2:fruit set;PS-3:pit hardening;PS-4:physiological maturity;PS-5:60 d after physiological maturity;and PS-6:fall)o f peach on the changes in soil organic carbon(SOC)fractions of different oxidizability,labile C pools,and C-cycle enzyme activities in soils,for two consecutive years(2015 and 2016)in the North-Western Himalayas(NWH).Peach rhizosphere soils were sampled at the topsoil(0-15 cm)and subsoil(16-30 cm)layers,along with rhizosphere soils from adjacent perennial grasses,which served as a control.Values for most of the assessed parameters,including very labile C,labile C,microbial biomass C,permanganate oxidizable C,dissolved organic C,mineralizable C,amylase activity,and carboxymethyl-cellulase activity,were significantly(P<0.05)higher at PS-3 than at other phenological stages of peach.Conversely,a sudden decline in these soil variables was recorded at PS-5,followed by a slight buildup at PS-6,particularly in the topsoil of the peach orchard.Short-term changes in organic C fractions of different oxidizability,influenced by peach phenological stage,significantly(P<0.05)affected C management index,C pool index,and lability index.Both the C management index and lability index showed their highest values at PS-3 and their lowest values at PS-5,clearly indicating short-term accretion and depletion of SOC,in tandem with the peach phenological events.Principal component analysis suggested that a composite of soil indicators,including microbial biomass C,dissolved organic C,amylase,and invertase,could help detect short-term changes in SOC content.It is concluded that peach phenological events had a major impact on the short-term variations of the studied soil variables,which could be attributed to changes in the above-and belowground plant residues,as well as the extent of nutrients and water acquisition.展开更多
The soil,Soul of Infinite Life,is the entity responsible for sustaining life on earth.In spite of significant advances in the service sector,agriculture remains the major provider of employment and source of revenue i...The soil,Soul of Infinite Life,is the entity responsible for sustaining life on earth.In spite of significant advances in the service sector,agriculture remains the major provider of employment and source of revenue in India.Soil testing is a valuable tool for evaluating the available nutrient status of soil and helps to determine the proper amount of nutrients to be added to a given soil based on its fertility and crop needs.In the current study,the soil test report values are used to classify several significant soil features like village wise soil fertility indices of Available Phosphorus(P),Available Potassium(K),Organic Carbon(OC)and Boron(B),as well as the parameter Soil Reaction(pH).The classification and prediction of the village wise soil parameters aids in reducing wasteful expenditure on fertilizer inputs,increase profitability,save the time of chemical soil analysis experts,improves soil health and environmental quality.These five classification problems are solved using the fast learning classification technique known as Extreme Learning Machine(ELM)with different activation functions like gaussian radial basis,sine-squared,hyperbolic tangent,triangular basis,and hard limit.After the performance analysis of ELMs with diverse activation functions for these soil parameter classifications,the gaussian radial basis function attains the maximum performance for four out of five problems,which goes above 80%in most of the accuracy rate calculations in every problem,followed by hyperbolic tangent,hard limit,triangular basis,and sine-squared.However,the performance of the final classification problem,i.e.the pH classification,gives moderate values with the gaussian radial basis and best performance(near 90%),with the hyperbolic tangent.展开更多
The paper examines the chemical composition of alluvial soils from the Zeya and Selemdzha River valleys, one of the branch rivers in the Amur River basin. It has been established that the compositions of these soils a...The paper examines the chemical composition of alluvial soils from the Zeya and Selemdzha River valleys, one of the branch rivers in the Amur River basin. It has been established that the compositions of these soils are characterized by a relative shortage of practically all analyzed macro-and microelements as compared with UCC(upper continental crust) and PAAS(postArhean Australian average shale) compositions. The chemical composition of alluvial soils approximates that of the soils in NE China and Korea due to similar climatic and geographic conditions. On the basis of relationships between major and trace elements and peculiarities of trace elements concentration it is shown that the alluvial soils in the middle reaches of the Zeya River were formed by the sources largely transformed by chemical weathering processes. By comparison, the soils in the Selemdzha River and lower reaches of the Zeya River(below the Selemdzha River mouth) are dominated by material to a large degree reworked by the physical processes rather than chemical ones. This inference conforms with specific geological settings of the water-collector.展开更多
Soil physical quality(SPQ)assessment is an important part in the evaluation of soil use,management,and conservation.It can be assessed using several physical properties,hydraulic indices,and functions.Soils from tropi...Soil physical quality(SPQ)assessment is an important part in the evaluation of soil use,management,and conservation.It can be assessed using several physical properties,hydraulic indices,and functions.Soils from tropical and temperate regions represent different physical behaviors,and the quantification of their physical properties is important to support soil evaluation and modelling.The objective of this study was to evaluate the SPQ in a subtropical field under maize crop cultivation according to its physical properties,hydraulic indices,and functions in an attempt to infer the spatial variability and to determine the behavior of soil physical structure across a spatial domain.Commonly used soil key physical variables,such as texture,bulk density,total porosity,saturated hydraulic conductivity,and organic carbon content,were measured in a regular grid with a soil sampling density of 30 points per hectare,covering an area of0.5 ha.Saturated hydraulic conductivity varied strongly between subsamples and in the field,suggesting the heterogeneity of the soil structure regarding water drainage.The physical variables were combined with other indicators,which were based on the soil water retention curve and the pore size distribution(PSD)function.Correlation analysis was performed to verify the relationship between the measured and calculated variables,and some strong linear correlations were revealed,such as between aeration energy index and microporosity(r=0.608)and water retention energy index with microporosity(r=0.532)and with bulk density(r=0.541).For most sampled locations,the shape and location parameters of PSD showed results outside of the optimum ranges,whereas the hydraulic energy indices and cumulative hydraulic energy functions presented values that were similar to those found for some tropical soils described in the literature.The spatial variability of these indices was described using semivariograms and kriged maps,indicating the variability of the SPQ in this field.展开更多
基金National Natural Science Foundation of China,No.40771016
文摘Eco-geographic regional system is formed by division or combination of natural features based on geographic relativity and comparison of major ecosystem factors(including biological and non-biological) and geographic zonality.In previous studies, soil types were often taken as a basis for soil regionalization.However, the quantitative characteristics of soil indicators are fitter than the qualitative ones of soil types for modern regionalization researches.Based on the second China's national soil survey data and the provincial soil resource information, by principal analysis and discriminant analysis, this paper discusses the appropriate soil indicators as the complement of eco-geographic region indicator systems and the relationships between these soil indicators and soil types in regionalization.The results show that five indicators are used in eco-geographic zonality in mid-temperate zone of eastern China which are organic matter content, cation exchange capacity, pH, clay content and bulk density in topsoils.With a regression-kriging approach, the maps of soil indicators in mid-temperate zone of eastern China are compiled with a resolution of 1 km in every grid and the indicative meanings of these soil indicators are discussed.By cluster analysis it is proved that these soil indicators are better than the soil types and soil regionalization in delineating eco-geographic regions.
文摘Assessing soil quality is essential for crop management and soil temporal changes. The present study aims to evaluate soil quality in the Ferralitic soils context countrywide. This assessment was done using multivariate soil quality indice (SQI) models, such as additive quality index (AQI), weighted quality indexes (WQI<sub>add</sub> and WQI<sub>com</sub>) and Nemoro quality index (NQI), applied to two approaches of indicator selection: total data set (TDS) and minimum data set (MDS). Physical and chemical soil indicators were extracted from the ORSTOM’s reports resulting from a sampling campaign in different provinces of Gabon. The TDS approach shows soil quality status according to eleven soil indicators extracted from the analysis of 1,059 samples from arable soil layer (0 - 30 cm depth). The results indicated that 87% of all provinces presented a very low soil quality (Q5) whatever the model. Among soil indicators, exchangeable K<sup>+</sup> and Mg<sup>2+</sup>, bulk density and C/N ratio were retained in MDS, using principal component analysis (PCA). In the MDS approach, 50 to 63% of provinces had low soil quality grades with AQI, WQI<sub>add</sub> and NQI, whereas the total was observed with WQI<sub>com</sub>. Only 25% of provinces had medium soil quality grades with AQI and NQI models, while 12.5% (NQI) and 25% (AQI) presented high quality grades. Robust statistical analyses confirmed the accuracy and validation (0.80 r P ≤ 0.016) of AQI, WQI<sub>add</sub> and NQI into the TDS and MDS approaches. The same sensitivity index value (1.53) was obtained with AQI and WQI<sub>add</sub>. However, WQI<sub>add</sub> was chosen as the best SQI model, according to its high linear regression value (R<sup>2</sup> = 0.82) between TDS and MDS. This study has important implications in decision-making on monitoring, evaluation and sustainable management of Gabonese soils in a pedoclimatic context unfavorable to plant growth.
文摘The estuary tides affect groundwater dynamics;these areas are susceptible to waterlogging and salinity issues.A study was conducted on two fields with a total area of 60 hectares under a center pivot irrigation system that works with solar energy and belong to a commercial farm located in Northern Sudan.To monitor soil salinity and calcium carbonate in the area and stop future degradation of soil resources,easy,non-intrusive,and practical procedures are required.The objective of this study was to use remote sensing-determined Sentinel-2 satellite imagery using various soil indices to develop prediction models for the estimation of soil electrical conductivity(EC)and soil calcium carbonate(CaCO_(3)).Geo-referenced soil samples were collected from 72 locations and analyzed in the laboratory for soil EC and CaCO_(3).The electrical conductivity of the soil saturation paste extract was represented by average values in soil dataset samples from two fields collected from the topsoil layer(0 to 15 cm)characteristic of the local salinity gradient.The various soil indices,used in this study,were calculated from the Sentinel-2 satellite imagery.The prediction was determined using the root mean square error(RMSE)and cross validation was done using coefficient of determination.The results of regression analysis showed linear relationships with significant correlation between the EC analyzed in laboratory and the salinity index-2“SI2”(Model-1:R^(2)=0.59,p=0.00019 and root mean square error(RMSE=1.32%)and the bare soil index“BSI”(Model-2:R^(2)=0.63,p=0.00012 and RMSE=6.42%).Model-1 demonstrated the best model for predicting soil EC,and validation R^(2)and RMSE values of 0.48%and 1.32%,respectively.The regression analysis results for soil CaCO_(3)determination showed linear relationships with data obtained in laboratory and the bare soil index“BSI”(Model-3:R^(2)=0.45,p=0.00021 and RMSE=1.29%)and the bare soil index“BSI”&Normalized difference salinity index“NDSI”(Model-4:R^(2)=0.53,p=0.00015 and RMSE=1.55%).The validation confirmed the Model-3 results for prediction of soil CaCO_(3)with R^(2)and RMSE values of 0.478%and 1.29%,respectively.Future soil monitoring programs might consider the use of remote sensing data for assessing soil salinity and CaCO_(3)using soil indices results generated from satellite image(i.e.,Sentinel-2).
基金financially supported by the National Basic Research Program of China (2015CB150403)
文摘The North China Plain（NCP） is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in relation to the grain yield for the winter wheat（Triticum aestivum L.）-maize（Zea mays L.） cropping system in a high-productivity farmland of the NCP. The field trials were conducted in three fields with different grain yield levels in Tai＇an City, Shandong Province, China, during the 2009–2012 period. Consistent field management strategies were applied in the three fields. Fifty-one physical and chemical indicators of the soil profile as related to grain yield were evaluated. An approximate maximum of 17.8% annual average grain yield difference was observed in the fields during the period of 2009–2012. The soil indicators were classified into three clusters with specific functions using cluster analysis, and three key indicators were extracted from each cluster to characterize the different soil properties of three fields. The first cluster represented soil water retention capacity, and the key indicator was available soil water（ASW）, which ranged from 153 to 187 mm in the 1.2 m profile and was correlated positively with grain yield. The second cluster represented soil water conductivity, as measured by saturated hydraulic conductivity（K s）. The higher yield field had a greater capacity to retain topsoil water for its lower K s（1.9 cm d^–1） in the 30–70 cm soil layer as compared to the lower yield field. The third cluster represented nutrient storage and supply, as indicated by the ratio of nutrient content to silt＋clay content of the top soil layer. The ratio of soil organic matter（OM）, total nitrogen（TN）, available P, exchangeable K＋ to silt＋clay content in the 0–20 cm soil layer were 19.0 g kg^–1, 1.6 g kg^–1, 94.7 mg kg^–1, 174.3 mg kg^–1 in the higher yield field, respectively, and correlated positively with the grain yield. By characterizing the differences in soil properties among fields with different yield levels, this study offers the scientific basis for increasing grain yield potential by improving the soil conditions in the NCP.
文摘Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil （0-15 cm） moisture availability were noted in soils under MPTs.
文摘Tobacco-planting plays an important role in ensuring the high-quality tobacco raw materials supply and the local social and economic development in Chenzhou City. In recent years whether tobacco-planting is better for the maintenance and improvement of soil fertility than other crop-planting has been highly concerned. In this study, 16 soil fertility indicators and soil integrated index (<em>IFI</em>) were compared by 21 pairs of fields in Chenzhou city under the rotations of tobacco-rice (TF) and rice-rice (RR), and results showed that, comparing the mean values of soil fertility indicators, the contents of OM, TN, AN, AK, S and <em>IFI</em> were extremely significantly higher in TR than those in RR (p < 0.01), the contents of Cu, Ca, Mg and Fe were significantly higher in TR than those in RR (p < 0.05), but Mn content was significantly lower in TR than those in RR (p < 0.05). Meanwhile the contents of TP, TK and AP were insignificantly higher in TR than those in RR, and the contents of B, Mo and Zn were insignificantly lower in TR than those in RR. The above significant differences in soil fertility indicators were mainly due to relatively higher fertilizer inputs and less nutrient removal during tobacco-growing season than during rape-growing season, the net increase of N, P<sub>2</sub>O<sub>5</sub> and K<sub>2</sub>O are 8.61, 5.25 and 24.89 kg per 667 m<sup>2</sup> respectively in tobacco-growing season, while the net decrease of N, P<sub>2</sub>O<sub>5 </sub>and K<sub>2</sub>O are 8.88, 4.70 and 4.62 kg per 667 m<sup>2</sup> respectively in rape-growing season. C.V. of soil fertility indicators and <em>IFI</em> were meanly lower in TR (52.25% and 15.95%, respectively) than those in RR (63.07% and 22.12%, respectively). Comparatively, tobacco-planting can improve soil fertility better than rape-planting when rotated with late rice in Chenzhou city. For tobacco-planting, Mg fertilizer should be applied for 23.8% TR fields, while more N, K, Ca, Mg, S and B fertilizers should be applied for 42.86%, 23.81%, 14.29%, 47.62%, 80.95% and 47.62% RR fields, respectively.
基金Project supported by the German Research Council, Germany (No. DFG Graduiertenkolleg 339).
文摘To evaluate the validity of different indices in estimating soil readily mineralizable N, soil microbial biomass （Nmic）, soil active N （SAN）, soluble organic N （SON）, net N mineralization rate （NNR） and gross N mineralization rate （GNR） in mineral soils （0-10 cm） from six forest stands located in central Germany were determined and compared with two sampling times： April and November. Additionally, soil density fractionation was conducted for incubated soils （with addition of ^15NH4-N and glucose, 40 days） to observe the sink of added ^15N in different soil fractions. The study showed that Nmic and NNR in most stands differed significantly （P 〈 0.05） between the two sampling times, but not GNR, SAN and SON. In November, no close relationships were found between GNR and other N indices, or between Nrnic, SON, and SAN and forest type. However, in April, GNR was significantly correlated （P 〈 0.05） with Nmic, SAN, and NNR along with Nmlc under beech being significantly higher （P 〈 0.05） than under conifers. Furthermore, density fractionation revealed that the light fraction （LF, 0.063-2 mm, 〉 1.7 gcm^-3） was not correlated with the other N indices. In contrast, results from the incubation study proved that more 15N was incorporated into the heavy fraction （HF 〈 0.063 ram, 〉 1.7 g cm^-3） than into LF, indicaing that more labile N existed in HF than in LF. These findings suggested that attention should be paid to the differences existing in N status between agricultural and forest soils.
文摘Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertility survey methods are needed. This study aimed to test the applicability of infrared spectroscopy （IR） as a diagnostic screening tool for making soil fertility recommendations in small-scale production systems. Soil fertility survey of 150 small-scale groundnut farms in western Kenya was conducted using a spatially stratified random sampling strategy. Soil properties examined were pH in water （pHw）, total carbon （C）, total nitrogen （N）, extractable phosphorus （P）, exchangeable potassium （K）, calcium （Ca）, magnesium （Mg） and texture. These properties were calibrated to mid-infrared （MIR） diffuse reflectance using partial least square regression （PLSR）. Cross-validated coefficient of determination （r2） values obtained from calibration models were 〉 0.80 for all properties, except P and K with 0.66 and 0.50 respectively. Soil nutritional deficiencies were evaluated using critical nutrient limits based on IR predictions and composite soil fertility indices （SFIs） developed from the soil properties using principal component analysis. The SFIs were calibrated to MIR soil spectral reflectance with cross-validated r： values 〉 0.80. The survey showed that 56% of the groundnut farms had severe soil nutrient constraints for production, especially exchangeable Ca, available P and organic matter. IR can provide a robust tool for farm soil fertility assessment and recommendation systems when backed up by conventional reference analyses. However, further work is required to test direct calibration of crop responses to spectral indicators and to improve prediction of extractable P and K tests.
文摘A study on community soil fertility management concepts and practices was conducted through rapid and participatory method of research in 15 villages of the Gourma region in Eastern part of Burkina Faso. These investigations aimed at determining farmers＇ knowledge on soil resources： local soil taxonomy and indicators of soil degradation, soil fertility management practices, and capacity for adoption of new technologies in soil fertility management. The results of the study showed that the main parameter for soil classification for all the investigated villages was soil texture composition; soil degradation was evaluated according to crops yield decrease and the development Striga sp. in 100% of the investigated villages; the use of organic manure and long term fellow were the main practices for soil fertility management; concerning the villages where modem technologies of soil fertility management were introduced, the lack of tools and capacity building were the main limiting factors of the adoption of these improved practices at small scale farmers＇ level. Even if discordance between scientific and local soil taxonomy were revealed by our investigations; significant similarities between indigenous and scientific indices of soil degradation were noticed. With regard to the actual magnitude of soil degradation; the local techniques of soil fertility management need to be improved and accessible to a big number of farmers.
文摘Awareness of how soil properties vary over agroecosystems(AES) is essential for understanding soil potentials and improving site-specific agricultural management strategies for a sustainable ecosystem. This study examined the characteristics of soil quality attributes and implications for agriculture in the Choke Mountain watershed in Ethiopia. Forty-seven composite soil samples(0–20 cm deep) were collected from lowland and valley fragmented(AES 1),midland plain with black soil(AES 2), midland plain with brown soil(AES 3),sloppy midland land(AES 4), and hilly and mountainous highlands(AES 5).Ten of 15 soil quality properties were significant(P < 0.05 or 0.01), including silt, exchangeable bases, cation exchange capacity, percent base saturation,p H, organic matter, total nitrogen and available phosphorous(P) across the five AES. However, all properties were variable with coefficients of variation from 7%(total porosity) to 169%(available P) across the AES. Although AES 2and 3 are affected by waterlogging and acidity, these two have better prospects for agriculture, but AES 1, 4, and 5 are unsuitable for agriculture because of soil erosion. Therefore, appropriate and applicable soil management strategies, particularly lime application and organic fertilizer, are fundamental to reversing soil acidity and improving soil fertility.
基金the EU Horizon 2020 projectInteractive Soil Quality Assessment in Europe and China for agriculturalproductivity and environmental resilience (iSQAPER), grant number 635750(mediated through the Swiss State Secretariat for Education, Research andInnovation). The University of Ljubljana, University of Trier, UniversityMiguel Hernandez, and the long-term field experiment owners providedsamples and data, and Lijbert Brussaard, Ron de Goede, Else Biinemann-Konig and Paul Mader provided constructive feedback on earlier versions ofthe manuscript.
文摘Developments in soil biology and in methodsto characterize soil organic carbon can potentially delivernovel soil quality indicators that can help identifymanagement practices able to sustain soil productivityand environmental resilience. This work aimed atsynthesizing results regarding the suitability of a range ofsoil biological and biochemical properties as novel soilquality indicators for agricultural management. The soilproperties, selected through a published literature review,comprised different labile organic carbon fractions [hydrophilicdissolved organic carbon, dissolved organic carbon,permanganate oxidizable carbon (POXC), hot waterextractable carbon and particulate organic matter carbon],soil disease suppressiveness measured using a Pythium-Lepidium bioassay, nematode communities characterizedby amplicon sequencing and qPCR, and microbialcommunity level physiological profiling measured withMicroResp™. Prior studies tested the sensitivity of each ofthe novel indicators to tillage and organic matter additionin ten European long-term field experiments (LTEs) andassessed their relationships with pre-existing soil qualityindicators of soil functioning. Here, the results of theseprevious studies are brought together and interpretedrelative to each other and to the broader body of literatureon soil quality assessment. Reduced tillage increasedcarbon availability, disease suppressiveness, nematoderichness and diversity, the stability and maturity of thefood web, and microbial activity and functional diversity.Organic matter addition played a weaker role in enhancingsoil quality, possibly due to the range of composition of theorganic matter inputs used in the LTEs. POXC was theindicator that discriminated best between soil managementpractices, followed by nematode indices based on functionalcharacteristics. Structural equation modeling showsthat POXC has a central role in nutrient retention/supply,carbon sequestration, biodiversity conservation, erosion control and disease regulation/suppression. The novelindicators proposed here have great potential to improveexisting soil quality assessment schemes. Their feasibilityof application is discussed and needs for future research are outlined.
基金supported by the National Basic Research Program of China (2009CB421302)the Joint Fundsof the National Natural Science Foundation of China(U1138303)+4 种基金the National Natural Science Foundation of China(41261090,41161063)the Open Foundation of State Key Laboratory of Resources and Environment Information Systems (2010KF0003SA)Scientific Research Foundation for Doctor (BS110125)Xinjiang Natural Science Foundation for Young Scholars (2012211B04)Research Fund for Training Young Teachers (XJEDU2012S03)
文摘Vegetation fractional coverage （VFC） is an important index to describe and evaluate the ecological system. The vegetation index is widely used to monitor vegetation coverage in the field of remote sensing （RS）. In this paper, the author conducted a case study of the delta oasis of Weigan and Kuqa rivers, which is a typical saline area in the Tarim River Watershed. The current study was based on the TM/ETM＋ images of 1989, 2001, and 2006, and supported by Geographic Information System （GIS） spatial analysis, vegetation index, and dimidiate pixel model. In addition, VBSl （vegetation, bare soil and shadow indices） suitable for TM/ETM＋ irrlages, constructed with FCD （forest canopy density） model principle and put forward by ITTO （International Tropical Timber Organization）, was used, and it was applied to estimate the VFC. The estimation accuracy was later prow^n to be up to 83.52%. Further, the study analyzed and appraised the changes in vegetation patterns and revealed a pattern of spatial change in the vegetation coverage of the study area by producing the map of VFC levels in the delta oasis. Forest, grassland, and farmland were the three main land-use types with high and extremely-high coverage, and they played an important role in maintaining the vegetation. The forest area determined the changes of the coverage area, whereas the other two land types affected the directions of change. Therefore, planting trees, protecting grasslands, reclaiming farmlands, and controlling unused lands should be included in a long-term program because of their importance in keeping regional vegetation coverage. Finally, the dynamic variation of VFC in the study area was evaluated according to the quantity and spatial distribution rendered by plant cover diigital images to deeply analyze the reason behind the variation.
基金the Geo-information Science and Technology Program (No. IRT 0438)
文摘This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The northern part of the Shaanxi province in China was taken as a case. Multi-temporal remotely sensed materials of both Landsat TM and thematic maps （ETM＋） were used as the bases to provide comprehensive views of surface conditions such as vegetation cover and salinization detection. With ERDAS ver. 9.1 software, the Normalized Differential Salinity Index （NDSl） and Salinity Index （S.I.） were computed and then evaluated for land degradation by salinization. Arc/Info ver. 9.2 software was used along with field observation data （GPS） for analysis. Using spatial analysis methods, results showed that 19 973.1 km^2 （72%） of land had no risk of land degradation by salinization, 3 684.7 km^2 （13%） had slight land degradation by salinization risk, 2 797.9 km^2 （10%） had moderate land degradation by salinization risk, and 1 218.9 km^2 （4%） of the total land area was at a high risk of land degradation by salinization. The study area, in general, is exposed to a high risk of soil salinization.
文摘Soil cleaning, the ability of the soil to immobilize the risk elements, belongs to important agroecosystem services in terms of protection of the hydrosphere and plant production from contamination. Dynamic monitoring of selected indicators of soil quality was realized in a special network of site on soil used for planting fast growing willow (Salix viminalis). Monitoring of the study site Kuchyňa (Mollic Fluvisol) is running since 2010 year. The fast-growing willow was planted on an area of about 43 hectares. Study site Kuchyňa belonged to the degraded contaminated sites, at the time of planting (the total contents of the risk elements were as follows: Cd 1.016 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, Zn 199.000 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, Ni 51.500 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>) There were positive changes in the total content of cadmium, zinc and nickel (in 2018 year), the zinc content decreased by 27% compared to 2010, the nickel content was lower by 23% and the Cd content by 57% in comparison to 2010 year, these elements have a declining trend during the monitored period. The remediation ability of the willow in relation to the risk elements was manifested by the accumulation of these elements in the wood mass and by their decrease in the soil below the limit value. The regulatory ecosystem service, the potential for the immobilisation of the risk elements, was evaluated based on the sum of the assessment of the contamination potential and the sorption potential of soil. The decrease of the total content of risk elements in the soil below the limit value was manifested in the increase of the potential of the agroecosystem regulatory service, the potential of risk element immobilisation, from very low category to medium category. If willow cultivation continued in the next decade, the value of risk element Zn would most likely reach the value 73 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, which is less than 50% of the limit value, based on the results of the predictive model. In the case of Cd, the soil would be completely cleaned and in the case of Ni, its total content in the soil would fall to 23 mg<span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span>kg<sup><span style="white-space:nowrap;">−</span>1</sup>, which is less than 40% of the limit value. The overall potential for contamination would fall into the category—very low (forecast for 2021 year). The higher potential of immobilisation reduces the risk of contaminants transport and thus prevents contamination of the other ecosystem components such as biota.
文摘The labile organic carbon(C)and C-related enzymes are sensitive indicators capturing alterations of soil organic matter(SOM),even in a short-time scale.Although the effects of crop husbandry and land use change on these attributes have been well studied,there is no consensus about how plant phenology may impact them.This study aimed to determine the short-term effect o f six distinct phenological stages(PS-1:full bloom;PS-2:fruit set;PS-3:pit hardening;PS-4:physiological maturity;PS-5:60 d after physiological maturity;and PS-6:fall)o f peach on the changes in soil organic carbon(SOC)fractions of different oxidizability,labile C pools,and C-cycle enzyme activities in soils,for two consecutive years(2015 and 2016)in the North-Western Himalayas(NWH).Peach rhizosphere soils were sampled at the topsoil(0-15 cm)and subsoil(16-30 cm)layers,along with rhizosphere soils from adjacent perennial grasses,which served as a control.Values for most of the assessed parameters,including very labile C,labile C,microbial biomass C,permanganate oxidizable C,dissolved organic C,mineralizable C,amylase activity,and carboxymethyl-cellulase activity,were significantly(P<0.05)higher at PS-3 than at other phenological stages of peach.Conversely,a sudden decline in these soil variables was recorded at PS-5,followed by a slight buildup at PS-6,particularly in the topsoil of the peach orchard.Short-term changes in organic C fractions of different oxidizability,influenced by peach phenological stage,significantly(P<0.05)affected C management index,C pool index,and lability index.Both the C management index and lability index showed their highest values at PS-3 and their lowest values at PS-5,clearly indicating short-term accretion and depletion of SOC,in tandem with the peach phenological events.Principal component analysis suggested that a composite of soil indicators,including microbial biomass C,dissolved organic C,amylase,and invertase,could help detect short-term changes in SOC content.It is concluded that peach phenological events had a major impact on the short-term variations of the studied soil variables,which could be attributed to changes in the above-and belowground plant residues,as well as the extent of nutrients and water acquisition.
文摘The soil,Soul of Infinite Life,is the entity responsible for sustaining life on earth.In spite of significant advances in the service sector,agriculture remains the major provider of employment and source of revenue in India.Soil testing is a valuable tool for evaluating the available nutrient status of soil and helps to determine the proper amount of nutrients to be added to a given soil based on its fertility and crop needs.In the current study,the soil test report values are used to classify several significant soil features like village wise soil fertility indices of Available Phosphorus(P),Available Potassium(K),Organic Carbon(OC)and Boron(B),as well as the parameter Soil Reaction(pH).The classification and prediction of the village wise soil parameters aids in reducing wasteful expenditure on fertilizer inputs,increase profitability,save the time of chemical soil analysis experts,improves soil health and environmental quality.These five classification problems are solved using the fast learning classification technique known as Extreme Learning Machine(ELM)with different activation functions like gaussian radial basis,sine-squared,hyperbolic tangent,triangular basis,and hard limit.After the performance analysis of ELMs with diverse activation functions for these soil parameter classifications,the gaussian radial basis function attains the maximum performance for four out of five problems,which goes above 80%in most of the accuracy rate calculations in every problem,followed by hyperbolic tangent,hard limit,triangular basis,and sine-squared.However,the performance of the final classification problem,i.e.the pH classification,gives moderate values with the gaussian radial basis and best performance(near 90%),with the hyperbolic tangent.
文摘The paper examines the chemical composition of alluvial soils from the Zeya and Selemdzha River valleys, one of the branch rivers in the Amur River basin. It has been established that the compositions of these soils are characterized by a relative shortage of practically all analyzed macro-and microelements as compared with UCC(upper continental crust) and PAAS(postArhean Australian average shale) compositions. The chemical composition of alluvial soils approximates that of the soils in NE China and Korea due to similar climatic and geographic conditions. On the basis of relationships between major and trace elements and peculiarities of trace elements concentration it is shown that the alluvial soils in the middle reaches of the Zeya River were formed by the sources largely transformed by chemical weathering processes. By comparison, the soils in the Selemdzha River and lower reaches of the Zeya River(below the Selemdzha River mouth) are dominated by material to a large degree reworked by the physical processes rather than chemical ones. This inference conforms with specific geological settings of the water-collector.
基金financed in part by the Coordination of Improvement of Higher Education Personnel(CAPES),Brazil(No.001)。
文摘Soil physical quality(SPQ)assessment is an important part in the evaluation of soil use,management,and conservation.It can be assessed using several physical properties,hydraulic indices,and functions.Soils from tropical and temperate regions represent different physical behaviors,and the quantification of their physical properties is important to support soil evaluation and modelling.The objective of this study was to evaluate the SPQ in a subtropical field under maize crop cultivation according to its physical properties,hydraulic indices,and functions in an attempt to infer the spatial variability and to determine the behavior of soil physical structure across a spatial domain.Commonly used soil key physical variables,such as texture,bulk density,total porosity,saturated hydraulic conductivity,and organic carbon content,were measured in a regular grid with a soil sampling density of 30 points per hectare,covering an area of0.5 ha.Saturated hydraulic conductivity varied strongly between subsamples and in the field,suggesting the heterogeneity of the soil structure regarding water drainage.The physical variables were combined with other indicators,which were based on the soil water retention curve and the pore size distribution(PSD)function.Correlation analysis was performed to verify the relationship between the measured and calculated variables,and some strong linear correlations were revealed,such as between aeration energy index and microporosity(r=0.608)and water retention energy index with microporosity(r=0.532)and with bulk density(r=0.541).For most sampled locations,the shape and location parameters of PSD showed results outside of the optimum ranges,whereas the hydraulic energy indices and cumulative hydraulic energy functions presented values that were similar to those found for some tropical soils described in the literature.The spatial variability of these indices was described using semivariograms and kriged maps,indicating the variability of the SPQ in this field.
