research article county-scale spatial distribution of soil enzyme … · 2019. 7. 31. · research...

Research ArticleCounty-Scale Spatial Distribution of Soil EnzymeActivities and Enzyme Activity Indices in Agricultural LandImplications for Soil Quality Assessment

Xiangping Tan1 Baoni Xie1 Junxing Wang1 Wenxiang He1

Xudong Wang1 and Gehong Wei2

1 College of Natural Resources and Environment Northwest AampF University Yangling Shaanxi 712100 China2 College of Life Science Northwest AampF University Yangling Shaanxi 712100 China

Correspondence should be addressed to Wenxiang He wenxianghenwsuafeducn

Received 26 May 2014 Revised 25 July 2014 Accepted 15 August 2014 Published 31 December 2014

Academic Editor Antonio Paz Gonzalez

Copyright copy 2014 Xiangping Tan et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Here the spatial distribution of soil enzymatic properties in agricultural land was evaluated on a county-wide (567 km2) scale inChangwu Shaanxi Province ChinaThe spatial variations in activities of five hydrolytic enzymeswere examined using geostatisticalmethods The relationships between soil enzyme activities and other soil properties were evaluated using both an integrated totalenzyme activity index (TEI) and the geometric mean of enzyme activities (GME) At the county scale soil invertase phosphataseand catalase activities were moderately spatially correlated whereas urease and dehydrogenase activities were weakly spatiallycorrelated Correlation analysis showed that both TEI andGMEwere better correlatedwith selected soil physicochemical propertiesthan single enzyme activities Multivariate regression analysis showed that soil OM content had the strongest positive effect whilesoil pH had a negative effect on the two enzyme activity indices In addition total phosphorous content had a positive effect on TEIand GME in orchard soils whereas alkali-hydrolyzable nitrogen and available potassium contents respectively had negative andpositive effects on these two enzyme indices in cropland soilsThe results indicate that land use changes strongly affect soil enzymeactivities in agricultural land where TEI provides a sensitive biological indicator for soil quality

1 Introduction

Soil is a natural resource playing key roles in organic matter(OM) decomposition nutrient cycling and water retentionand release [1] Soils are subject to natural or environmentaldegradation often accompanied by erosion and leachingDegradation of soils occurs even without the interventionof human agricultural practices [2 3] thus threateningthis valuable resource Soil quality particularly in arid andsemiarid areas needs to be preserved and improved forfood security and environmental protection [4] Previouslya variety of quantitative measures including soil physico-chemical properties indicative of the fundamental contextof soil functions have been extensively used to assess soilquality [5] However most soil physicochemical propertieschange slowly in response to the environmental stress withsignificant changes commonly detected only after many

years By contrast soil biological properties are sensitiveindicators for soil quality which rapidly respond to minorenvironmental changes in the soil [6]

Soil enzyme activity is a potential indicator of soil qualitydue to its high sensitivity to external interference and theease of measurement [7]The activities of hydrolytic enzymesare frequently measured to evaluate the effect of land use onbiological processes in soils related to carbon (C) nitrogen(N) phosphate (P) and sulfur (S) cycling [8 9] Soil invertasedeserves special recognition because its substrate sucroseis one of the most abundant soluble sugars in plants and ispartially responsible for the breakdown of plant litter in soils[10] Urease enzyme is responsible for the hydrolysis of ureafertilizer into NH

3and CO

2with a concomitant rise in soil

pH [11] Phosphatases are a broad group of enzymes thatcatalyze hydrolysis of esters and anhydrides of phosphoricacid Apart from being a good indicator of soil fertility

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 535768 11 pageshttpdxdoiorg1011552014535768

2 The Scientific World Journal

phosphatase enzymes play key roles in the soil system [8]Additionally dehydrogenase enzyme activity is commonlyused as an indicator of biological activity in soils [11] Catalaseactivity in soils is considered to be an indicator of aerobicmicrobial activity and has been related to both the numberof aerobic microorganisms and soil fertility [12]

Enzyme activity generally increases with the rise of soilorganic matter (OM) content Higher enzyme activity indi-cates larger microbial communities and greater stability ofenzymes adsorbed on humic materials [13] The activities ofextracellular enzymes in soil vary significantly with seasonsand geographical locations [14] as well as soil depth [15 16]Together these findings indicate that soil enzyme activitieshave broad-scale spatial variability depending on the envi-ronmental conditions Due to seasonal and spatial variabilitysingle biological properties cannot be accurate measures ofsoil quality [17 18] Therefore multiparametric indices arerecommended for environmental impact assessment of agro-ecosystems and nonagricultural soils [19 20] In fact existingmultiparametric indices have been found less sensitive toseasonal variations [21] than single properties

Conventional statistical procedures assume that varia-tions in soil properties are randomly distributed within sam-pling units However soil properties are continuous variableswhose values at any location are expected to vary to differentextents according to the direction and spacing of samplingpoints Therefore increasing emphasis has been put on thefact that variations in a soil property are not entirely randomwithin a field Such spatial structure of soil property shouldbe taken into account in processing data [22] Knowledgeregarding the spatial distribution of soil enzyme activityacross the landscape has great implications for interpretingthe spatial pattern of OM decomposition and the rate ofnutrient mineralization at regional scales [23] When takingbiological properties as the indicator of soil quality it is neces-sary to consider the spatial variability of biological propertiesthemselves as well as the underlying influencing factors [24]Most studies have investigated the spatial variability of soilenzyme activities based on pot andormicroplot experiments[25 26] while few reports are available at regional scales[22ndash24 27ndash29] Because the experimental data are not alwaysapplicable to actual field conditions it is necessary to carryout field studies on the spatial variability of soil enzymeactivity especially in arid and semiarid areas associated withserious soil erosion

The present study was conducted on Chinarsquos LoessPlateau which is known for its deep deposits of loess Fre-quent and long-term anthropogenic activities have negativelyaffected the soil environment on the Loess Plateau resultingin significant degradation of natural vegetation and intensesoil erosion [30 31] Although a number of surveys havequantified soil erosion and the spatial variability of soilproperties in the plateau region [32 33] there is little infor-mation on the spatial distribution of soil enzyme activitiesacross the large-scale landscapeThe responses of soil enzymeactivities to geographical locations on the Loess Plateauremain unclear and related research is urged to providereference data for integrated soil quality management

The objectives of this study were (1) to quantify the activi-ties of five soil enzymes (invertase urease phosphatase cata-lase and dehydrogenase) and selected soil physicochemicalproperties across an entire county (Changwu) on the LoessPlateau (2) to investigate the spatial variability of soil enzymeactivities in a representative area in the Hilly-Gully Region ofLoess Plateau and (3) to explore the relationships betweensoil enzyme activities and physicochemical properties usingan integrated soil enzyme activity index (TEI) and to compareit with the geometric mean of enzyme activities (GME)

2 Materials and Methods

21 Study Area Changwu County (567 km2) is located inXianyang City Shaanxi Province China (34∘591015840ndash35∘81015840N107∘171015840ndash107∘581015840E) (Figure 1) This county is part of the Hilly-Gully Region of Loess Plateau It mainly consists of lowrolling hills and deep narrow gulliesThe dominant soil typesare Cumuli-Ustic Isohumosols (dark loessial soil) and Loessi-Orthic Primosols (cultivated loessial soils) The altituderanges from 847 to 1274masl Changwu has a continentalsemiaridmonsoon climate withmeanmonthly temperaturesranging from minus99∘C in January to 244∘C in July The annualaverage temperature is 92∘C and the annual precipitation is573mm Heavy rainstorms occasionally occur in this countymainly between June and September The driest season isduring winter from December to February

22 Soil Sampling and Chemical Analysis In late October2008 soils were sampled at the 0ndash20 cm depth from 245locations in 171 villages of Changwu (Figure 1) The samplesfrom croplands were taken randomly in every village andthose from apple orchards were randomly taken in every twovillages across the county The sampling locations were iden-tified using a global positioning system (GARMIN GPS72)One soil sample in the cropland consisted of five individualsubsamples which were taken randomly within a 10m radiusfrom each sampling point Similarly for a sample in appleorchard five subsamples were taken from each of three rowsTherewere 170 soil samples from croplands and 75 from appleorchards All soil samples were air-dried at room temperatureand then passed through a 10mm sieve

Soil physicochemical analysis was conducted on 025mmsieved samples using routine analytical methods [34] TheOM content was determined by oxidation with K

2Cr2O7

H2SO4 Total N content was analyzed following the Kjeldahl

digestion procedure Alkali-hydrolyzableN content wasmea-sured using the alkaline hydrolysis diffusion method Fortotal P and K analyses the samples were decomposed withsodium hydroxide (solid) at 720∘C and extracted with hotwater followed bymolybdenum blue spectrophotometry andatomic absorption spectrophotometry respectively AvailableP was extracted with 05molsdotLminus1 sodium bicarbonate andquantified by molybdenum antimony blue spectrophotom-etry Available K was extracted with 1molsdotLminus1 ammoniumacetate and quantified by atomic absorption spectrophotom-etry Soil particle size distribution was determined usinga pipette method Cation exchange capacity (CEC) was

The Scientific World Journal 3

45∘

Neimenggu

Ningxia hui

Gansu Shanxi

HubeiSichuan

Shaanxi

Shaanxi

Soil sampleRiver

120∘

90∘

30∘

15∘

China

Henan

N

N

107∘50

998400

107∘52

998400107

∘44

998400

150∘

60∘

0∘

35∘11

998400

34∘57

998400

35∘10

998400

35∘4998400

35∘18

998400

0 1000 2000

National boundary

Changwu 5 100

(km)

(km)

Figure 1 Location of Changwu County and distribution of sampling points in the study area

quantified using a 1molsdotLminus1 ammonium acetate exchangemethod Soil pH was measured in a 5 1 water to soil slurrywith an electronic pH meter (Mettler Toledo FE20)

23 Soil EnzymeActivityAssays Enzyme activitiesweremea-sured with 1mm sieved soil samples in unbuffered extractsolutions meant to simulate the field conditions

Invertase activity was determined as described by [35]Briefly 5 g of air-dried soil was mixed together with 15mL of8 sucrose solution 5mL of distilled water and 5 drops oftoluene After incubation for 24 h at 37∘C the soil solutionwas centrifuged at 4000 rpm for 5min and a 1mL aliquotwas transferred to a volumetric flask containing 3mL of 35-dinitrosalicylic acidThemixture was heated for 5minWhenthe solution reached room temperature glucose contentwas quantified colorimetrically at 508 nm on a spectropho-tometer (INESA 722N) Invertase activity was expressed as120583g glucosesdotgminus1 soilsdothminus1

For the urease activity assay 5 g of air-dried soil wasmixed with 5mL of toluene 20mL of distilled water and10mL of 10 urea solution After incubation at 37∘C for24 h the soil suspension was centrifuged at 4000 rpm for5min and a 1mL aliquot was treated with 4mL of sodiumphenol solution (containing 100mL of 66M phenol solutionand 100mL of 68M NaOH) and 3mL of 09 sodium

hypochlorite solution The ammonium released into thesolution was quantified colorimetrically at 578 nm on aspectrophotometer Urease activity was expressed as 120583gNH

4-

Nsdotgminus1 soilsdothminus1 [35]For phosphatase activity assay 5 g of air-dried soil was

mixed with 5 drops of toluene 10mL of disodium phenylphosphate solution and 10mL of distilled water The suspen-sion was incubated for 24 h at 37∘C and then centrifuged at4000 rpm for 5min The supernatant was colored with 025ammonia-ammonium chloride buffer at pH 96 05mL of2 4-aminoantipyrine and 05mL of 8 potassium ferro-cyanideThe phenol content was determined colorimetricallyat 510 nm on a spectrophotometer Phosphatase activity wasexpressed as 120583g phenolsdotgminus1 soilsdothminus1 [35]

Catalase and dehydrogenase activities were assayed usingthe method of [11] For catalase activity assay 2 g of air-driedsoil was mixed with 40mL of distilled water and 5mL of03 H

2O2 The soil slurry was shaken for 20min at 150 rpm

The remaining peroxide was stabilized by adding 5mL of15M sulfuric acid and the solution was then immediatelycentrifuged at 4000 rpm for 5minThe peroxide in the super-natant was titrated with 005MKMnO

4 Catalase activity was

expressed as mL KMnO4sdotgminus1 soilsdothminus1

For dehydrogenase activity assay 3 g of air-dried soil wasmixed with a 3 triphenyl tetrazolium chloride solution


as the substrate and 125 to 175mL of distilled water Thesoil slurry was mixed thoroughly and incubated at 37∘Cfor 24 h Thereafter triphenyl formazan was extracted withmethanol and quantified by colorimetric analysis at 485 nmDehydrogenase activity was expressed as 120583g TPFsdotgminus1 soilsdothminus1[11] and all enzyme activities were calculated as the mean oftwo replicates

24 Statistical and Geostatistical Analyses Descriptive statis-tics (arithmetic mean maximum and minimum medianstandard deviation coefficient of variation skewness andkurtosis) and Pearson product moment correlation analysiswere conducted using SPSS 18 for Windows (SPSS IncChicago IL USA) Data normality was tested by one-sampleKolmogorov-Smirnov test

The semivariogram analysis was used to assess the spatialstructure of the studied variablesThen theOrdinary Kriginginterpolation was used to estimate the unknown values atunsampled locations and to map the spatial variability ofsoil properties and TEI [36] The sample semivariogram wascalculated using

120574 (ℎ) =

1

2119873 (ℎ)

119873(ℎ)

sum

119894=1

[119885 (119909

119894) minus 119885 (119909

119894+ ℎ)]

2

(1)

where 120574(ℎ) is the semivariance for interval distance class ℎthat is the distance separating sample points 119909

119894and 119909

119894+ ℎ

119873(ℎ) is the number of sample couples for the lag interval ℎand 119885(119909

119894) and 119885(119909

119894+ ℎ) are measured values at points 119894 and

119894 + ℎ respectivelyThree variogram models (spherical Gaussian and expo-

nential) were fitted to the sample semivariograms in thisresearchThe best fittedmodel should have the smallest resid-ual sum of squares (RSS) and the largest coefficient of deter-mination (1198772) between predicted values and the measuredvalues of soil properties Then the best fitted models wereused to provide input parameters for Kriging interpolationThe estimated values were obtained using

119885

lowast(119909

0) =

119899

sum

119894=1

120582

119894119885 (119909

119894) (2)

where 119885lowast(1199090) is the predicted value at point 119909

0 119885(119909119894) are the

measured values at sampling location 119909119894 120582119894is the weight to

be assigned to sample 119909119894 and 119899 is the number of sites within

the neighborhood searched for the interpolationHere log or Box-Cox transformation was used when the

original data was not normally distributed Semivariancecalculations of the soil properties were conducted based onthemaximum sampling distance of 17 km which was dividedinto 15 lag distance classes separated by an average of11 km No significant anisotropy was considered because theanisotropy ratio was less than 25 [37] The cross validationprocedure was used to assess the models fitted to experi-mental semivariograms After a semivariogram model hasbeen obtained the Kriging technique was applied to obtaina map of estimates The geostatistical analysis was performedin ArcGIS (version 100 ERIS Redlands CA USA)

25 Calculation of Soil Enzyme Activity Indices The inte-grated total enzyme activity index (TEI) was calculated usingthe following equation [20]

TEI =119894

sum

119899=1

119883

119894

119883

119894

(119899 = 1 2 3 4 5) (3)

where 119883119894is the activity of soil enzyme 119894 and 119883

119894is the mean

activity of enzyme 119894 in all samplesThe geometric mean of enzyme activities (GME) was

calculated by (4) discussed elsewhere [38] as

GME

=

5radicInvertase times Urease times Phosphatase times Catalase times Dehydrogenase

(4)

3 Results

31 Descriptive Statistics of Soil Properties The OM contentof surface soil samples averaged 1257 gsdotkgminus1 and the total Nconcentration averaged 089 gsdotkgminus1 across the county Bothparameters varied substantially from 516 to 1825 gsdotkgminus1 forOM content and from 028 to 137 gsdotkgminus1 for total N contentThe soils were mostly fine in texture with an average claycontent of 33 Soil pH ranged from 780 to 909 with ameanof 859 (Table 1)

Invertase activity of surface soil samples (0ndash20 cmdepth) ranged from 102 to 707120583g glucosesdotgminus1 hminus1 with amean of 379120583g glucosesdotgminus1 hminus1 Urease activity rangedfrom 316 to 108 120583gNH

4

+-Nsdotgminus1 hminus1 with a mean of250 120583gNH

4

+-Nsdotgminus1 hminus1 Phosphatase activity ranged from151 to 716 120583g phenolsdotgminus1 soilsdothminus1 with a mean of3488 120583g phenolsdotgminus1 soilsdothminus1 Catalase activity rangedfrom 458 to 131mLKMnO

4sdotgminus1 soilsdothminus1 with a mean

of 879mLKMnO4sdotgminus1 soilsdothminus1 Dehydrogenase activity

ranged from 015 to 306 120583g TPFsdotgminus1 hminus1 with a mean of250 120583g TPFsdotgminus1 hminus1 (Table 1) The coefficients of variation(CV) were 28 for invertase activity 53 for urease activity25 for phosphatase activity 22 for catalase activity and49 for dehydrogenase activity

The activities of all enzymes and the levels of OMAN AK and CEC were normally distributed (one-sampleKolmogorov-Smirnov test 119875 gt 005) Total N and pH lev-els were negatively skewed and nonnormally distributedwhereas total P total K available P and clay contents werepositively skewed and nonnormally distributed The under-lying reasons for normal or nonnormal distribution of thesevariables were unknown but management and spatial effectsseemed to play a role

32 Relationships of Soil Physicochemical Properties and Enzy-matic Activities Results of the correlation analysis in allsoil samples showed that the OM content was significantlycorrelated with invertase urease phosphatase and dehydro-genase activities (119875 lt 001) but not with catalase activity(119875 gt 005) The alkali-hydrolyzable N content was strongly


Table 1 Descriptive statistics of selected soil physicochemical properties and enzyme activities in surface horizon (0ndash20 cm) of ChangwuCounty Shaanxi Province China (119899 = 245)

Parameters Range Minimum Maximum Mean Standarddeviation

K-S Z AsympSig (2-tailed) Skewness Kurtosis

OMg kgminus1 1309 516 1825 1257 222 121 011 minus052 14Total Ng kgminus1 109 028 137 089 019 264 000 minus046 078Total Pg kgminus1 145 017 162 067 026 251 000 114 195Total Kg kgminus1 1142 1668 281 2223 195 223 000 019 01Alkali-hydrolyzable Nmg kgminus1 8575 1925 105 5968 1572 101 026 002 minus004Available Pmg kgminus1 4671 254 4925 1706 1051 166 001 153 188Available Kmg kgminus1 450 6313 51313 19936 9422 076 062 08 minus009CECcmol kgminus1 1684 668 2352 1391 329 108 019 073 minus012Clay 3309 1741 505 3319 514 159 001 051 227pH 120 789 909 859 023 181 000 minus064 014Invertase120583g glucosesdotgminus1 soilsdothminus1 6051 10207 70718 37926 10634 079 055 032 004Urease120583gNH4-N gminus1 soilsdothminus1 1047 316 10786 3786 2007 138 005 077 03Phosphatase120583g phenolsdotgminus1 soilsdothminus1 5655 1512 7167 3488 883 079 057 057 124CatalasemL KMnO4sdotg

minus1 soilsdothminus1 855 458 1313 879 197 086 044 011 minus064Dehydrogenase120583g TPFsdotgminus1 soilsdothminus1 291 015 306 129 063 099 028 048 minus028K-S Z Kolmogorov-Smirnov Z OM organic matter N nitrogen P phosphorous K potassium and CEC cation exchange capacity

correlated with invertase urease phosphatase catalase anddehydrogenase activities (119875 lt 001) No significant corre-lation was found between soil pH and phosphatase activity(119875 gt 005) However soil pH was positively correlatedwith dehydrogenase activity (119875 lt 005) and negativelycorrelated with invertase urease and catalase activities (119875 lt001 Table 2) Additionally soil phosphatase activity wasextremely significantly correlated with invertase (119903 = 0409119875 lt 001) and urease activities (119903 = 0228 119875 lt 001) andcatalase activity was significantly correlated with invertase(119903 = 0146 119875 lt 005) and urease activities (119903 = 0144 119875 lt005) Soil dehydrogenase activity was significantly correlatedwith invertase (119903 = 0519 119875 lt 001) phosphatase (119903 = 0649119875 lt 001) and catalase activities (119903 = minus0174 119875 lt 001)

33 Spatial Structure of Soil Properties Semivariance analysisshowed that the soil properties generally had spatial depen-dence (Table 3) The semivariograms all exhibited spatialstructure The experimental semivariograms for soil dehy-drogenase activity available K content CEC level and claycontent were fitted by exponential models The experimentalsemivariogram for total K content was fitted by a sphericalmodelThe experimental semivariograms for other soil prop-erties were fitted by the Gaussian models

The spatial dependence of the data was confirmed bytotal variance (Sill) composed of structural (C) and nuggetvariances (Co) Nugget to sill ratio ([CoSill]) for soilenzyme activities was 67 and that for soil physicochemicalproperties was 54 Nugget to sill ratios of urease anddehydrogenase activities accounted for 85 and 71 of thetotal variance respectively These values were significantlyhigher than sill and nugget effects Available K content hadthe largest nugget to sill ratio among all soil properties The

effective ranges of phosphatase and urease activities weregreater than those of invertase catalase and dehydrogenaseactivities (39 53 and 2 km resp)

The Krigingmaps showed that soil OM total N and CEClevels showed similar spatial distribution patterns with thelowest values occurring in the center of the county (Figures2(a) 2(b) and 2(h)) Soil alkali-hydrolyzable N availableP contents and pH value were highest in the central andsouthern parts and lowest in the northern part of Changwu(Figures 2(e) 2(f) and 2(j)) In contrast total P contentincreased from the south to the northwest (Figure 2(c))Soil total K available K and clay contents had no obviousvariation trends across the county (Figures 2(d) 2(g) and2(i)) The distribution of these three properties did notcorrespond to the topographical feature of the study areaor to the spatial distribution of the other soil propertiesSoil invertase urease and catalase activities were highestin the northern area in Changwu County followed by thecentral and southern areas (Figures 2(k) 2(l) and 2(n)) Soilphosphatase activity was highest in the center of the county(Figure 2(m)) Dehydrogenase activity decreased from thesouthwest to the northeast (Figure 2(o))

34 Enzymatic Activity Indices A main novelty of this studywas to introduce the integrated index TEI as a dimensionlessparameter for easy comparison of the combined enzymeactivity and the quality of each soil sampleWe also comparedthis index with the commonly used GME index The TEIvalues of total orchard and cropland soil samples varied from187 to 743 27 to 74 and 18 to 74 with a median valueof 507 49 and 507 respectively The mean TEI value of allsoil samples was estimated to be 5 The GME values of totalorchard and cropland soil samples varied from 69 to 33 10


Table 2 Correlation coefficients (Pearson 119903 value) between soil physicochemical properties and enzyme activities in surface horizon (0ndash20 cm) of Changwu County (119899 = 245)

Invertase Urease Phosphatase Catalase DehydrogenaseOM 0547lowastlowast 0386lowastlowast 0580lowastlowast minus006 0469lowastlowast

Total N 0300lowastlowast 0431lowastlowast 0243lowastlowast 0255lowastlowast 003Total P minus006 0317lowastlowast minus0176lowastlowast 0315lowastlowast minus0325lowastlowast

Total K 011 011 012 minus0213lowastlowast 0246lowastlowast

Alkali-hydrolyzable N 0393lowastlowast 0192lowastlowast 0486lowastlowast minus0462lowastlowast 0552lowastlowast

Available P 005 0366lowastlowast 009 minus0186lowastlowast minus002Available K 000 0358lowastlowast 0147lowast 009 minus006CEC 011 0291lowastlowast minus013 0718lowastlowast minus0322lowastlowast

Clay 011 0127lowast 002 0297lowastlowast minus010pH minus0167lowastlowast minus0380lowastlowast 005 minus0529lowastlowast 0154lowast

lowast and lowastlowast represent statistical significances at the 5 and 1 levels respectively OM organic matter N nitrogen P phosphorous K potassium and CECcation exchange capacity

Table 3 Parameters for variogram models of soil physicochemical properties enzyme activities and TEI in surface horizon (0ndash20 cm) ofChangwu County (119899 = 245)

Parameters Model 119862

0119862

0+ 119862 [119862

0(1198620+ 119862)]100 Rangekm RMSS

OM Gaussian 303 436 6953 93 109Total N Gaussian 002 004 5705 749 105Total P Gaussian 004 005 7774 626 105Total K Spherical 089 307 2883 331 101Alkali-hydrolyzable N Gaussian 10093 2437 4141 1133 106Available P Gaussian 026 032 8178 1563 108Available K Exponential 019 021 8989 1027 101CEC Exponential 001 004 3106 1046 101Clay Exponential 718 2464 2914 523 097pH Gaussian 002 005 3778 936 103Invertase Gaussian 1689 2793 6045 389 100Urease Gaussian 887 104 8534 936 102Phosphatase Gaussian 159 26 6131 1299 101Catalase Gaussian 132 244 5427 533 098Dehydrogenase Exponential 019 027 7126 199 096TEI Gaussian 065 130 5015 084 1071198620 nugget variance119862 structural variance1198620+119862 sill RMSS root-mean-square standardized OM organicmatter N nitrogen P phosphorous K potassiumand CEC cation exchange capacity

to 30 and 22 to 33 with a median value of 216 208 and 221respectivelyThemean GME values of different groups of soilsamples were estimated to be 213 205 and 217 respectively

The TEI and GME values were most correlated withthe activities of invertase urease phosphatase catalase anddehydrogenase except orchard soil catalase activity (Table 4)Pearson correlation analysis showed that TEI and GMEwere positively correlated with soil OM total N and alkali-hydrolyzable N contents but negatively correlated with pHlevel In addition the TEI and GME values of total andorchard soil samples were positively correlated with total Kcontent The TEI and GME values of total and cropland soilsamples were positively correlated with available P and Kcontents The TEI values of total and cropland soil sampleswere positively correlated with CEC (Table 4)

Multivariate regression analysiswas carried out to investi-gate the relationship between soil physicochemical properties

and enzyme activity indices (TEI and GME) (Table 5)Among the soil properties measured in this equation soilOM content had the strongest positive effect while soil pHhad a negative effect on the two indices Additionally totalP content had a positive effect on TEI and GME in orchardsoils The alkali-hydrolyzable N and available K contents hadnegative and positive effects on TEI and GME in croplandsoils while the alkali-hydrolyzable N and available P contentshad positive and negative effects on both enzyme activityindices in total soils

4 Discussion

41 Spatial Structure of Soil Enzyme Activities Wilding [39]previously described a classification scheme for identifyingthe variability of soil properties based on their CV values


35∘20

998400N

35∘12

998400N

35∘4998400N

N

1241

1241

1316

1316

1316

1392

1392

1165

1090

788

10151241

1165

5 100

(km)

107∘45

998400E 107∘55

998400E

(a) OM

087

087

093

099

099

064

059

070

104 081

081

081

093

093

093

099

093

099

087

087

076

076

076

076

5 100

(km)

N

107∘45

998400E 107∘55

998400E

087

(b) Total N

099

078

078

078

078

078

085

092

085

064

064

078

071

071

043

043

057 057

057

057

050

050

050

760

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(c) Total P

2410

2146

2058

2322

2498

2586

1882

2586

2146

2146

2234

2234

2234

2058

2322

2058

5 100

(km)

N

107∘45

998400E 107∘55

998400E

2322

2234

(d) Total K

35∘20

998400N

35∘12

998400N

35∘4998400N

5129

4616

5641

5641

41033590

7180

7180

7180

6154

6154

6154

6154

6667 6667

5 100

(km)

N

107∘45

998400E 107∘55

998400E

6667

(e) Alkali-hydrolyzable N

2142

1413

1049

1778

1960866

1596

1231

1231

12311778

1596

1596

1778

1413

1596

1413

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(f) Available P

6230

13311

14771

14771

22068

16230

19149

19149

19149

19149

19149

17690

17690

20608

22068

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(g) Available K

1422

1196

1309

1309

97

1761

1761

1874

1535

1083

1083

10831083

1648

1648

11961196

1422

1761

1196

1422

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(h) CEC

35∘20

998400N

35∘12

998400N

35∘4998400N

2766

4068

2245

4329

3287

3547

3547

3547

3547

3027

3027

3027

3287

3287

3287

3808

3808

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(i) Clay

855

869

826

862

876883

883

883847

847

847

840

840

876

876

876

855

869

869

862

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(j) pH

37583

344 31

344 31

43888

31279

47040

40736

28127

28127

43888

37583

34431

40736

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(k) Invertase

3248

4036

3642

4430

2854

2459

5219

2065

48253642

2854

2854

3642

3642

2854

2854

4036

2459

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(l) Urease

35∘20

998400N

35∘12

998400N

35∘4998400N

107∘45

998400E 107∘55

998400E

3610

3610

3878

3343

4413

2808

2541

4146

2808

3878

3878

3075

3075

3343

3075

3343

5 100

(km)

N

(m) Phosphatase

107∘45

998400E 107∘55

998400E

1039

748865

865

981

1156

923

923

865

748

981

807

807

807

807

1098

748

1098

1098

690

690

N

5 100

(km)

(n) Catalase

107∘45

998400E 107∘55

998400E

131

084 068

100

179

052

163

163

147

116

163

147

147

147

131

131

116

116

116

131

084

163

N

5 100

(km)

(o) Dehydrogenase

107∘45

998400E 107∘55

998400E

521

465

576

409

354

632

465

465

409

521

521

465

465

465

521

521

521

5 100

(km)

N

(p) TEI

Figure 2 Spatial distribution patterns of soil physicochemical properties and enzyme activities and TEI in surface horizon of ChangwuCounty


Table 4 Pearson correlation coefficients between soil physicochemical properties and enzyme activity indices in surface horizon (0ndash20 cm)of Changwu County

SamplesOrchard Cropland Total(119899 = 75) (119899 = 170) (119899 = 245)

Enzyme activity index TEI GME TEI GME TEI GMEOM 0566lowastlowast 0569lowastlowast 0696lowastlowast 0693lowastlowast 0659lowastlowast 0655lowastlowast

Total N 0299lowastlowast 0315lowastlowast 0459lowastlowast 0448lowastlowast 0407lowastlowast 0395lowastlowast

Total P minus0103 minus009 0095 0054 0021 minus0021Total K 0291lowast 0252lowast 0137 0118 0179lowastlowast 0142lowast

Alkali-hydrolyzable N 0314lowastlowast 0287lowast 0543lowastlowast 0574lowastlowast 0459lowastlowast 0461lowastlowast

Available P 0074 0086 0353lowastlowast 0355lowastlowast 0187lowastlowast 0139lowast

Available K 0217 0217 0267lowastlowast 0238lowastlowast 0235lowastlowast 0175lowastlowast

CEC 0092 0109 0174lowast 0137 0148lowast 0121Clay 0063 0057 012 0091 0103 0086pH minus0280lowast minus0294lowast minus0277lowastlowast minus0259lowastlowast minus0271lowastlowast minus0243lowastlowast

Invertase 0707lowastlowast 0688lowastlowast 0655lowastlowast 0661lowastlowast 0663lowastlowast 0673lowastlowast

Urease 0501lowastlowast 0486lowastlowast 0739lowastlowast 0699lowastlowast 0624lowastlowast 0559lowastlowast

Phosphatase 0749lowastlowast 0751lowastlowast 0725lowastlowast 0729lowastlowast 0712lowastlowast 0737lowastlowast

Catalase 0149 0174 0267lowastlowast 0232lowastlowast 0225lowastlowast 0219lowastlowast

Dehydrogenase 0811lowastlowast 0801lowastlowast 0681lowastlowast 0705lowastlowast 0690lowastlowast 0729lowastlowast

GME 0990lowastlowast 1 0986lowastlowast 1 0981lowastlowast 1lowast and lowastlowast represent statistical significances at the 5 and 1 levels respectively OM organic matter N nitrogen P phosphorous K potassium CEC cationexchange capacity GME geometric mean of enzyme activities and TEI total enzyme activity

Table 5 Multiple linear regressions between soil physicochemical properties and enzyme activity indices in surface horizon (0ndash20 cm) ofChangwu County

Samples Multiple regression equation 119877

2119875

Orchard(119899 = 75)

log10TEI = 1214 + 0722 times log

10OM minus 0157 times pH minus 0131 times log

10Total P 0491 lt0001

log10GME = 1911 + 0792 times log


10Total P 0483 lt0001

Cropland(119899 = 170)



10AN + 009 times log

10Available K 063 lt0001





Total(119899 = 245)


10OM minus 0126 times pH + 038 times log

10AN minus 0061 times log

10Available P 053 lt0001





According to Wildingrsquos classification the CV values of soilinvertase phosphatase and catalase activities are relativelysmall (22ndash28) whereas those of urease and dehydrogenaseactivities (49ndash53) are at the medium level Soil enzymeactivities have close relationships with soil biology and aresensitive in discriminating among soil management prac-tices such as fertilization by means of animal manure orgreen manurescrop residues and municipal refuse amend-ment as well as among tillage treatments However aprevious report indicated that dehydrogenase and celluloseactivities in the surface soil horizon of an arable land (2 km2)had small CV values (18 and 26 resp) [26] Bonmati et al[25] observed that the CV values for soil urease phosphataseand protease activities ranged from 28 to 60 in a 15mtimes 40m meadow Smith and Halvorson [24] reported theCV values of 33 for phosphatase activity and 36 fordehydrogenase activity in agricultural land (119899 = 220) These

findings confirmed that the spatial variability of soil enzymeactivities varied in different ecosystems

Knowledge regarding the spatial variability of soil biolog-ical properties is critical for the management and improve-ment of agricultural soil quality Reliable information onthe range of spatial relationships makes it possible to definethe sampling strategy needed for accurately mapping soilbiological properties [22] In the present study the bestmodel of semivariogram varied depending on the kindsof soil enzymes and the effective ranges of soil enzymesdecreased in the order of phosphataserarr ureaserarr catalaserarrinvertaserarr dehydrogenase (Table 3) Semivariograms forenzyme activities exhibited spatial correlated distances thatranged from 2 to 13 km (Table 3) Likewise Askın andKızılkaya [22] recently had reported that the zone (4500times 4500m) of influence of soil urease activity was approxi-mately 193 km In general however field-scale (50 ha) studies


indicate that the effective ranges of soil dehydrogenase andcellulose activities are 843ndash933m [26]Thedifference amongthose studies may depend highly on the size of sample areaand the sampling distance Both soil properties and scaleeffect have strong effects on the spatial distribution of enzymeactivity The spatial structure of soil properties is complexand contrasting range values have been reported Thereforefuture research should consider the size of study area andthe distances between sampling pointsThemost appropriatesampling scheme and the separation distance between sam-pling points for future data collection are highly importantand should be determined in preliminary studies [23]

The ratio of nugget to sill can be used as a criterion to clas-sify the strength of the spatial dependence of soil properties(lt25 strong spatial dependence 25ndash75 moderate spatialdependence andgt75weak spatial dependence) [40] In thepresent study the nugget to sill ratios descended in the orderof urease activity (85) gt dehydrogenase activity (71) gtphosphatase activity (61) gt invertase activity (60) gt cata-lase activity (54) The activities of invertase phosphatasedehydrogenase and catalase are more spatially dependentthan urease activity The moderate spatial dependence ofinvertase phosphatase dehydrogenase and catalase activitiesindicates that these enzyme activities are primarily controlledby specific geological factors and have better correlationTheweak spatial dependence of soil urease activities indicatesthat the environment has a stronger impact than geographicaldistance on the spatial distribution of relevantmicrobial com-munities Similarly high nugget effects have been observedfor dehydrogenase activity in no-till field which was croppedwith corn (Zeamays L) and soybean (Glycinemax (L)Merr)(627) [40] Cambisol soil under winter wheat (684) [26]and no-till wheat crop soil (707) [41] The variability ofweakly spatially dependent parameters may be caused byagricultural practices such as application of fertilizers andtillage whereas strongly spatially dependent parameters areinfluenced by variations in innate soil characteristics suchas texture and mineralogy [40] The differences in spatialdependency of soil enzyme activities may be related todifferent spatial distribution of various microbial groups andsoil fertilizer which reflects the influence of different soiltopography vegetation and agricultural practices

Visualizing the spatial distribution of soil biotic compo-nents contributes to the understanding of spatial structureand thus may help with accurate prediction and mappingof soil microbial properties [42] The activities of five soilenzymes in Changwu County showed patchy distributionrelated to soil physicochemical properties tested (Figure 2)For example invertase urease and catalase activities weregenerally highest in the northern part of Changwu As forsoil properties the OM total N total P and CEC levels werehigh while the alkali-hydrolyzable N available P available Kand soil pH levels were relatively low in the northern partof Changwu Spatially different distribution of the enzymaticactivity is related to the variations in soil OM contentthe activity of related living organisms and the intensityof biological processes [22] Therefore it is not surprisingthat microbial properties show cross-dependence amongthemselves and with other soil properties depending on the

ecosystem [42] Understanding of the spatial distribution ofphysicochemical indicators for soil quality is an importantstep for explaining the spatial variability of biological param-eters The statistical results analysis showed that there werehighly significant correlations between soil enzyme activities(invertase urease phosphatase catalase and dehydrogenase)and several physicochemical properties (OM total N totalP alkali-hydrolyzable N CEC and pH levels) in ChangwuThese strong relationships confirm that soil enzyme activitiesprovide a meaningful integrative measure of soil physico-chemical properties and biological soil fertility which thusmay play a role in monitoring soil biological quality [43]

42 Implications for Assessing Soil Quality by a Biological oran Integrated Enzyme Activity Index Results of the multi-variate regression analysis indicated that soil OM and pHlevels respectively had stronger positive and negative effectsthan other soil properties on TEI and GME MeanwhileTEI and GME had stronger positive correlation with soilphysicochemical properties than individual enzyme activities(Table 4) Generally the OM content positively affects extra-cellular enzyme activity in soil [42 43] The adsorption ofenzymemolecules to soil particles andOMmaterials possiblyprotected the enzymes against soil pH changes Alternativelythis could be attributed to the dependence of microbialactivity (hence enzyme production) on the supply of organicsubstrate (organic C availability) In such cases the organicC content and enzyme activity would be related to each othervia microbial biomass [26]

Soil biological properties are highly sensitive to environ-mental stress and thus can be used to assess quality Anysoil quality index should include several biological variablesso as to better reflect the complex processes affecting soilquality and to compensate for the wide variations occurringin individual properties [44] For instance the TEI valuesshowed more similar spatial distribution patterns with soilphysicochemical properties (Figure 2(p) 119899 = 245) As theTEI index introduced in this study involves only five soilenzymes further large-scale studies are recommended toverify the applicability of TEI as an integrated activity index ofsoil enzymes in different ecosystems A more comprehensiveand accurate biological indicator for changes in soil qualitycan be obtained by taking into consideration more enzymecomponents andor microbial parameters that are indicativeof key soil biological processes These indicators must bequantified on a local and landscape basis as a means formaking small-scale and regional management decisions [24]In view of the limitations of single soil biological properties itis recommended to develop and use multiparametric indicessuch as TEI for providing and integrating more informationon soil quality

5 Conclusion

Results of the conventional and geostatistical analyses indi-cate that the spatial variability of agricultural soil properties iscomplex in ChangwuCounty Spatial distributionmaps showthat soil invertase urease and catalase activities are high in


the northern area soil phosphatase activity is high in thecentral area and soil dehydrogenase activity is high in thesouthwestern area of the county The spatial patterns of soilquality are better reflected using an integrated soil enzymeindex which provides a sensitive biological indicator for soilquality as compared with the single enzyme activities

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Authorsrsquo Contribution

Xiangping Tan contributed to data analysis laboratory assayand paper preparation Baoni Xie contributed to data analy-sis JunxingWang contributed to laboratory assay WenxiangHe contributed to experiment design and paper preparationand revision XudongWang and GehongWei provided paperrevision and experiment design

Acknowledgments

This work was supported by the National Hi-tech Researchand Development Program of China (no 2012AA101402)the Chinese Universities Scientific Fund and the KnowledgeInnovation Project of Chinese Academy of Sciences (KSCX-YW-09-07)

References

[1] K Ritz H I J Black C D Campbell J A Harris and CWood ldquoSelecting biological indicators for monitoring soils aframework for balancing scientific and technical opinion toassist policy developmentrdquo Ecological Indicators vol 9 no 5pp 1212ndash1221 2009

[2] M M Mikha and C W Rice ldquoTillage and manure effects onsoil and aggregate-associated carbon and nitrogenrdquo Soil ScienceSociety of America Journal vol 68 no 3 pp 809ndash816 2004

[3] K Jin S Sleutel D Buchan et al ldquoChanges of soil enzymeactivities under different tillage practices in the Chinese LoessPlateaurdquo Soil and Tillage Research vol 104 no 1 pp 115ndash1202009

[4] K Nosrati ldquoAssessing soil quality indicator under different landuse and soil erosion using multivariate statistical techniquesrdquoEnvironmental Monitoring and Assessment vol 185 no 4 pp2895ndash2907 2013

[5] E Puglisi A A M Del Re M A Rao and L GianfredaldquoDevelopment and validation of numerical indexes integratingenzyme activities of soilsrdquo Soil Biology and Biochemistry vol 38no 7 pp 1673ndash1681 2006

[6] J A Pascual C Garcia T Hernandez J L Moreno and MRos ldquoSoil microbial activity as a biomarker of degradation andremediation processesrdquo Soil Biology and Biochemistry vol 32no 13 pp 1877ndash1883 2000

[7] A K Bandick and R P Dick ldquoField management effects on soilenzyme activitiesrdquo Soil Biology and Biochemistry vol 31 no 11pp 1471ndash1479 1999

[8] R P Dick ldquoSoil enzyme activities as indicators of soil qualityrdquo inDefining Soil Quality for a Sustainable Environment JWDoran

D C Coleman D F Bezdicek and B A Stewart Eds pp 107ndash124 SSSA Madison Wis USA 1994

[9] E Kandeler andEMurer ldquoAggregate stability and soilmicrobialprocesses in a soil with different cultivationrdquoGeoderma vol 56no 1ndash4 pp 503ndash513 1993

[10] W T Frankenberger Jr and J B Johanson ldquoFactors affectinginvertase activity in soilsrdquo Plant and Soil vol 74 no 3 pp 313ndash323 1983

[11] R G Burns Soil Enzymes Academic Press London UK 1978[12] C Trasar-Cepeda F Camina M C Leiros and F Gil-Sotres

ldquoAn improved method to measure catalase activity in soilsrdquo SoilBiology and Biochemistry vol 31 no 3 pp 483ndash485 1999

[13] SMarinari and L V Antisari ldquoEffect of lithological substrate onmicrobial biomass and enzyme activity in brown soil profiles inthe northern Apennines (Italy)rdquo Pedobiologia vol 53 no 5 pp313ndash320 2010

[14] J Paz-Ferreiro C Trasar-CepedaM C Leiros S Seoane and FGil-Sotres ldquoEffect of management and climate on biochemicalproperties of grassland soils from Galicia (NW Spain)rdquo Euro-pean Journal of Soil Biology vol 46 no 2 pp 136ndash143 2010

[15] C Wittmann M A Kahkonen H Ilvesniemi J Kurola andM S Salkinoja-Salonen ldquoAreal activities and stratificationof hydrolytic enzymes involved in the biochemical cycles ofcarbon nitrogen sulphur and phosphorus in podsolized borealforest soilsrdquo Soil Biology and Biochemistry vol 36 no 3 pp425ndash433 2004

[16] E Alarcon-Gutierrez C Floch C Augur J L Petit F Ziarelliand S Criquet ldquoSpatial variations of chemical compositionmicrobial functional diversity and enzyme activities in aMediterranean litter (Quercus ilex L) profilerdquoPedobiologia vol52 no 6 pp 387ndash399 2009

[17] R P Dick and V V S R Gupta ldquoA conceptual model for therole of abiontic soil enzymes in microbial ecology a potentialanalogue for soil qualityrdquo in Soil Biota Management in Sustain-able Farming Systems C E Pankhurst B M Doube V V S RGupta and P R Grace Eds pp 167ndash168 CSIRO PublicationsEast Melbourne Australia 1994

[18] P Nannipieri S Grego and B Ceccanti ldquoEcological signifi-cance of biological activityrdquo in Soil Biochemistry J M Bollagand G Stotzky Eds pp 293ndash355 Marcel Dekker New YorkNY USA 1990

[19] J Paz-Ferreiro and S Fu ldquoBiological indices for soil qualityevaluation perspectives and limitationsrdquo Land Degradation ampDevelopment 2014

[20] W He X Tan X Wang M Tang and M Hao ldquoStudy on totalenzyme activity index in soilrdquoActa Pedologica Sinica vol 47 no6 pp 211ndash215 2010 (Chinese)

[21] J Paz-Ferreiro C Trasar-Cepeda M del Carmen Leiros SSeoane and F Gil-Sotres ldquoIntra-annual variation in biochem-ical properties and the biochemical equilibrium of differentgrassland soils under contrasting management and climaterdquoBiology and Fertility of Soils vol 47 no 6 pp 633ndash645 2011

[22] T Askın and R Kızılkaya ldquoThe spatial variability of ureaseactivity of surface agricultural soils within urban areardquo Journalof Central European Agriculture vol 6 no 2 pp 161ndash166 2005

[23] A Piotrowska J Długosz B Namysłowska-Wilczynska and RZamorski ldquoField-scale variability of topsoil dehydrogenase andcellulase activities as affected by variability of some physico-chemical propertiesrdquo Biology and Fertility of Soils vol 47 no1 pp 101ndash109 2011


[24] J L Smith and J J Halvorson ldquoField scale studies on the spatialvariability of soil quality indicators in Washington State USArdquoApplied and Environmental Soil Science vol 2011 Article ID198737 7 pages 2011

[25] M Bonmati B Ceccanti and P Nanniperi ldquoSpatial variabilityof phosphatase urease protease organic carbon and total nitro-gen in soilrdquo Soil Biology amp Biochemistry vol 23 no 4 pp 391ndash396 1991

[26] S Smolinski J Długosz A Piotrowska and R Zamorski ldquoSpa-tial variability of soil dehydrogenases and cellulases activities ina field scalerdquo Polish Journal of Soil Science vol 41 no 1 pp 73ndash80 2008

[27] Y Gao P Zhou L Mao Y Zhi C Zhang and W Shi ldquoEffectsof plant species coexistence on soil enzyme activities and soilmicrobial community structure under Cd and Pb combinedpollutionrdquo Journal of Environmental Sciences vol 22 no 7 pp1040ndash1048 2010

[28] KWallenius H Rita AMikkonen et al ldquoEffects of land use onthe level variation and spatial structure of soil enzyme activitiesand bacterial communitiesrdquo Soil Biology and Biochemistry vol43 no 7 pp 1464ndash1473 2011

[29] Z Hossain and S-I Sugiyama ldquoGeographical structure of soilmicrobial communities in northern Japan effects of distanceland use type and soil propertiesrdquo European Journal of SoilBiology vol 47 no 2 pp 88ndash94 2011

[30] H Shi and M Shao ldquoSoil and water loss from the Loess Plateauin Chinardquo Journal of Arid Environments vol 45 no 1 pp 9ndash202000

[31] F-S Chen D-H Zeng and X-Y He ldquoSmall-scale spatialvariability of soil nutrients and vegetation properties in semi-arid Northern Chinardquo Pedosphere vol 16 no 6 pp 778ndash7872006

[32] Y Wang B Fu Y Lu C Song and Y Luan ldquoLocal-scale spatialvariability of soil organic carbon and its stock in the hilly areaof the Loess Plateau ChinardquoQuaternary Research vol 73 no 1pp 70ndash76 2010

[33] B Fu and L Chen ldquoAgricultural landscape spatial patternanalysis in the semi-arid hill area of the Loess Plateau ChinardquoJournal of Arid Environments vol 44 no 3 pp 291ndash303 2000

[34] R K Lu Analytical Methods of Soil and Agricultural ChemistryChina Agricultural Science and Technology Press BeijingChina 1999

[35] S Y Guan D S Zhang and ZM Zhang Soil Enzyme andTheirResearch Methods China Agricultural Science and TechnologyPress Beijing China 1987

[36] DG Krige ldquoA statistical approach to some basicmine valuationproblems on the witwatersrandrdquo Journal of the ChemicalMetallurgical and Mining Society of South Africa vol 52 no 6pp 119ndash139 1952

[37] B B Trangmar R S Yost and G Uehara ldquoApplication of geo-statistics to spatial studies of soil propertiesrdquoAdvances in Agron-omy vol 38 no 1 pp 45ndash94 1985

[38] M B Hinojosa R Garcıa-Ruız B Vinegla J A Carreira RGarcıa-Ruız and B Vinegla ldquoMicrobiological rates and enzymeactivities as indicators of functionality in soils affected by theAznalcollar toxic spillrdquo Biology and Fertility of Soils vol 36 no10 pp 1637ndash1644 2004

[39] L Wilding ldquoSpatial variability its documentation accomoda-tion and implication to soil surveysrdquo in Soil Spatial VariabilityD R Nielsen and J Bouma Eds pp 166ndash194 PudocWagenin-gen The Netherlands 1985

[40] C A Cambardella T B Moorman J M Novak et al ldquoField-scale variability of soil properties in central Iowa soilsrdquo SoilScience Society of America Journal vol 58 no 5 pp 1501ndash15111994

[41] W J Staddon M A Locke and R M Zablotowicz ldquoSpatialvariability of cyanazine dissipation in soil from a conservation-managed fieldrdquo in Water Quality Assessments in the MississippiDelta Regional Solutions M T Nett M A Locke and D APennington Eds pp 179ndash193 National Scope WashingtonDC USA 2004

[42] E Katsalirou S Deng D L Nofziger A Gerakis and S DFuhlendorf ldquoSpatial structure of microbial biomass and activityin prairie soil ecosystemsrdquo European Journal of Soil Biology vol46 no 3-4 pp 181ndash189 2010

[43] T Askın and R Kızılkaya ldquoAssessing spatial variability of soilenzyme activities in pasture topsoils using geostatisticsrdquo Euro-pean Journal of Soil Biology vol 42 no 4 pp 230ndash237 2006

[44] C Trasar-Cepeda C Leiros F Gil-Sotres and S SeoaneldquoTowards a biochemical quality index for soils an expressionrelating several biological and biochemical propertiesrdquo Biologyand Fertility of Soils vol 26 no 2 pp 100ndash106 1998

Submit your manuscripts athttpwwwhindawicom

Forestry ResearchInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Applied ampEnvironmentalSoil Science

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Atmospheric SciencesInternational Journal of



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International Journal of

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Geological ResearchJournal of

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OceanographyInternational Journal of


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Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


ClimatologyJournal of


phosphatase enzymes play key roles in the soil system [8]Additionally dehydrogenase enzyme activity is commonlyused as an indicator of biological activity in soils [11] Catalaseactivity in soils is considered to be an indicator of aerobicmicrobial activity and has been related to both the numberof aerobic microorganisms and soil fertility [12]

Enzyme activity generally increases with the rise of soilorganic matter (OM) content Higher enzyme activity indi-cates larger microbial communities and greater stability ofenzymes adsorbed on humic materials [13] The activities ofextracellular enzymes in soil vary significantly with seasonsand geographical locations [14] as well as soil depth [15 16]Together these findings indicate that soil enzyme activitieshave broad-scale spatial variability depending on the envi-ronmental conditions Due to seasonal and spatial variabilitysingle biological properties cannot be accurate measures ofsoil quality [17 18] Therefore multiparametric indices arerecommended for environmental impact assessment of agro-ecosystems and nonagricultural soils [19 20] In fact existingmultiparametric indices have been found less sensitive toseasonal variations [21] than single properties

Conventional statistical procedures assume that varia-tions in soil properties are randomly distributed within sam-pling units However soil properties are continuous variableswhose values at any location are expected to vary to differentextents according to the direction and spacing of samplingpoints Therefore increasing emphasis has been put on thefact that variations in a soil property are not entirely randomwithin a field Such spatial structure of soil property shouldbe taken into account in processing data [22] Knowledgeregarding the spatial distribution of soil enzyme activityacross the landscape has great implications for interpretingthe spatial pattern of OM decomposition and the rate ofnutrient mineralization at regional scales [23] When takingbiological properties as the indicator of soil quality it is neces-sary to consider the spatial variability of biological propertiesthemselves as well as the underlying influencing factors [24]Most studies have investigated the spatial variability of soilenzyme activities based on pot andormicroplot experiments[25 26] while few reports are available at regional scales[22ndash24 27ndash29] Because the experimental data are not alwaysapplicable to actual field conditions it is necessary to carryout field studies on the spatial variability of soil enzymeactivity especially in arid and semiarid areas associated withserious soil erosion

The present study was conducted on Chinarsquos LoessPlateau which is known for its deep deposits of loess Fre-quent and long-term anthropogenic activities have negativelyaffected the soil environment on the Loess Plateau resultingin significant degradation of natural vegetation and intensesoil erosion [30 31] Although a number of surveys havequantified soil erosion and the spatial variability of soilproperties in the plateau region [32 33] there is little infor-mation on the spatial distribution of soil enzyme activitiesacross the large-scale landscapeThe responses of soil enzymeactivities to geographical locations on the Loess Plateauremain unclear and related research is urged to providereference data for integrated soil quality management

The objectives of this study were (1) to quantify the activi-ties of five soil enzymes (invertase urease phosphatase cata-lase and dehydrogenase) and selected soil physicochemicalproperties across an entire county (Changwu) on the LoessPlateau (2) to investigate the spatial variability of soil enzymeactivities in a representative area in the Hilly-Gully Region ofLoess Plateau and (3) to explore the relationships betweensoil enzyme activities and physicochemical properties usingan integrated soil enzyme activity index (TEI) and to compareit with the geometric mean of enzyme activities (GME)

2 Materials and Methods

21 Study Area Changwu County (567 km2) is located inXianyang City Shaanxi Province China (34∘591015840ndash35∘81015840N107∘171015840ndash107∘581015840E) (Figure 1) This county is part of the Hilly-Gully Region of Loess Plateau It mainly consists of lowrolling hills and deep narrow gulliesThe dominant soil typesare Cumuli-Ustic Isohumosols (dark loessial soil) and Loessi-Orthic Primosols (cultivated loessial soils) The altituderanges from 847 to 1274masl Changwu has a continentalsemiaridmonsoon climate withmeanmonthly temperaturesranging from minus99∘C in January to 244∘C in July The annualaverage temperature is 92∘C and the annual precipitation is573mm Heavy rainstorms occasionally occur in this countymainly between June and September The driest season isduring winter from December to February

22 Soil Sampling and Chemical Analysis In late October2008 soils were sampled at the 0ndash20 cm depth from 245locations in 171 villages of Changwu (Figure 1) The samplesfrom croplands were taken randomly in every village andthose from apple orchards were randomly taken in every twovillages across the county The sampling locations were iden-tified using a global positioning system (GARMIN GPS72)One soil sample in the cropland consisted of five individualsubsamples which were taken randomly within a 10m radiusfrom each sampling point Similarly for a sample in appleorchard five subsamples were taken from each of three rowsTherewere 170 soil samples from croplands and 75 from appleorchards All soil samples were air-dried at room temperatureand then passed through a 10mm sieve

Soil physicochemical analysis was conducted on 025mmsieved samples using routine analytical methods [34] TheOM content was determined by oxidation with K

2Cr2O7

H2SO4 Total N content was analyzed following the Kjeldahl

digestion procedure Alkali-hydrolyzableN content wasmea-sured using the alkaline hydrolysis diffusion method Fortotal P and K analyses the samples were decomposed withsodium hydroxide (solid) at 720∘C and extracted with hotwater followed bymolybdenum blue spectrophotometry andatomic absorption spectrophotometry respectively AvailableP was extracted with 05molsdotLminus1 sodium bicarbonate andquantified by molybdenum antimony blue spectrophotom-etry Available K was extracted with 1molsdotLminus1 ammoniumacetate and quantified by atomic absorption spectrophotom-etry Soil particle size distribution was determined usinga pipette method Cation exchange capacity (CEC) was


45∘

Neimenggu

Ningxia hui

Gansu Shanxi

HubeiSichuan

Shaanxi

Shaanxi

Soil sampleRiver

120∘

90∘

30∘

15∘

China

Henan

N

N

107∘50

998400

107∘52

998400107

∘44

998400

150∘

60∘

0∘

35∘11

998400

34∘57

998400

35∘10

998400

35∘4998400

35∘18

998400

0 1000 2000

National boundary

Changwu 5 100

(km)

(km)







4-













120574 (ℎ) =

1

2119873 (ℎ)

119873(ℎ)

sum

119894=1

[119885 (119909

119894) minus 119885 (119909

119894+ ℎ)]

2

(1)


119894and 119909

119894+ ℎ


119894) and 119885(119909




119885

lowast(119909

0) =

119899

sum

119894=1

120582

119894119885 (119909

119894) (2)


0 119885(119909119894) are the






TEI =119894

sum

119899=1

119883

119894

119883

119894

(119899 = 1 2 3 4 5) (3)


119894is the mean



GME

=


(4)

3 Results



4


4






























0119862

0+ 119862 [119862

0(1198620+ 119862)]100 Rangekm RMSS






4 Discussion



35∘20

998400N

35∘12

998400N

35∘4998400N

N

1241

1241

1316

1316

1316

1392

1392

1165

1090

788

10151241

1165

5 100

(km)

107∘45

998400E 107∘55

998400E

(a) OM

087

087

093

099

099

064

059

070

104 081

081

081

093

093

093

099

093

099

087

087

076

076

076

076

5 100

(km)

N

107∘45

998400E 107∘55

998400E

087

(b) Total N

099

078

078

078

078

078

085

092

085

064

064

078

071

071

043

043

057 057

057

057

050

050

050

760

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(c) Total P

2410

2146

2058

2322

2498

2586

1882

2586

2146

2146

2234

2234

2234

2058

2322

2058

5 100

(km)

N

107∘45

998400E 107∘55

998400E

2322

2234

(d) Total K

35∘20

998400N

35∘12

998400N

35∘4998400N

5129

4616

5641

5641

41033590

7180

7180

7180

6154

6154

6154

6154

6667 6667

5 100

(km)

N

107∘45

998400E 107∘55

998400E

6667


2142

1413

1049

1778

1960866

1596

1231

1231

12311778

1596

1596

1778

1413

1596

1413

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(f) Available P

6230

13311

14771

14771

22068

16230

19149

19149

19149

19149

19149

17690

17690

20608

22068

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(g) Available K

1422

1196

1309

1309

97

1761

1761

1874

1535

1083

1083

10831083

1648

1648

11961196

1422

1761

1196

1422

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(h) CEC

35∘20

998400N

35∘12

998400N

35∘4998400N

2766

4068

2245

4329

3287

3547

3547

3547

3547

3027

3027

3027

3287

3287

3287

3808

3808

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(i) Clay

855

869

826

862

876883

883

883847

847

847

840

840

876

876

876

855

869

869

862

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(j) pH

37583

344 31

344 31

43888

31279

47040

40736

28127

28127

43888

37583

34431

40736

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(k) Invertase

3248

4036

3642

4430

2854

2459

5219

2065

48253642

2854

2854

3642

3642

2854

2854

4036

2459

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(l) Urease

35∘20

998400N

35∘12

998400N

35∘4998400N

107∘45

998400E 107∘55

998400E

3610

3610

3878

3343

4413

2808

2541

4146

2808

3878

3878

3075

3075

3343

3075

3343

5 100

(km)

N

(m) Phosphatase

107∘45

998400E 107∘55

998400E

1039

748865

865

981

1156

923

923

865

748

981

807

807

807

807

1098

748

1098

1098

690

690

N

5 100

(km)

(n) Catalase

107∘45

998400E 107∘55

998400E

131

084 068

100

179

052

163

163

147

116

163

147

147

147

131

131

116

116

116

131

084

163

N

5 100

(km)

(o) Dehydrogenase

107∘45

998400E 107∘55

998400E

521

465

576

409

354

632

465

465

409

521

521

465

465

465

521

521

521

5 100

(km)

N

(p) TEI




















2119875

Orchard(119899 = 75)



10Total P 0491 lt0001



10Total P 0483 lt0001

Cropland(119899 = 170)









Total(119899 = 245)



















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics















45∘

Neimenggu

Ningxia hui

Gansu Shanxi

HubeiSichuan

Shaanxi

Shaanxi

Soil sampleRiver

120∘

90∘

30∘

15∘

China

Henan

N

N

107∘50

998400

107∘52

998400107

∘44

998400

150∘

60∘

0∘

35∘11

998400

34∘57

998400

35∘10

998400

35∘4998400

35∘18

998400

0 1000 2000

National boundary

Changwu 5 100

(km)

(km)







4-













120574 (ℎ) =

1

2119873 (ℎ)

119873(ℎ)

sum

119894=1

[119885 (119909

119894) minus 119885 (119909

119894+ ℎ)]

2

(1)


119894and 119909

119894+ ℎ


119894) and 119885(119909




119885

lowast(119909

0) =

119899

sum

119894=1

120582

119894119885 (119909

119894) (2)


0 119885(119909119894) are the






TEI =119894

sum

119899=1

119883

119894

119883

119894

(119899 = 1 2 3 4 5) (3)


119894is the mean



GME

=


(4)

3 Results



4


4






























0119862

0+ 119862 [119862

0(1198620+ 119862)]100 Rangekm RMSS






4 Discussion



35∘20

998400N

35∘12

998400N

35∘4998400N

N

1241

1241

1316

1316

1316

1392

1392

1165

1090

788

10151241

1165

5 100

(km)

107∘45

998400E 107∘55

998400E

(a) OM

087

087

093

099

099

064

059

070

104 081

081

081

093

093

093

099

093

099

087

087

076

076

076

076

5 100

(km)

N

107∘45

998400E 107∘55

998400E

087

(b) Total N

099

078

078

078

078

078

085

092

085

064

064

078

071

071

043

043

057 057

057

057

050

050

050

760

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(c) Total P

2410

2146

2058

2322

2498

2586

1882

2586

2146

2146

2234

2234

2234

2058

2322

2058

5 100

(km)

N

107∘45

998400E 107∘55

998400E

2322

2234

(d) Total K

35∘20

998400N

35∘12

998400N

35∘4998400N

5129

4616

5641

5641

41033590

7180

7180

7180

6154

6154

6154

6154

6667 6667

5 100

(km)

N

107∘45

998400E 107∘55

998400E

6667


2142

1413

1049

1778

1960866

1596

1231

1231

12311778

1596

1596

1778

1413

1596

1413

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(f) Available P

6230

13311

14771

14771

22068

16230

19149

19149

19149

19149

19149

17690

17690

20608

22068

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(g) Available K

1422

1196

1309

1309

97

1761

1761

1874

1535

1083

1083

10831083

1648

1648

11961196

1422

1761

1196

1422

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(h) CEC

35∘20

998400N

35∘12

998400N

35∘4998400N

2766

4068

2245

4329

3287

3547

3547

3547

3547

3027

3027

3027

3287

3287

3287

3808

3808

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(i) Clay

855

869

826

862

876883

883

883847

847

847

840

840

876

876

876

855

869

869

862

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(j) pH

37583

344 31

344 31

43888

31279

47040

40736

28127

28127

43888

37583

34431

40736

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(k) Invertase

3248

4036

3642

4430

2854

2459

5219

2065

48253642

2854

2854

3642

3642

2854

2854

4036

2459

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(l) Urease

35∘20

998400N

35∘12

998400N

35∘4998400N

107∘45

998400E 107∘55

998400E

3610

3610

3878

3343

4413

2808

2541

4146

2808

3878

3878

3075

3075

3343

3075

3343

5 100

(km)

N

(m) Phosphatase

107∘45

998400E 107∘55

998400E

1039

748865

865

981

1156

923

923

865

748

981

807

807

807

807

1098

748

1098

1098

690

690

N

5 100

(km)

(n) Catalase

107∘45

998400E 107∘55

998400E

131

084 068

100

179

052

163

163

147

116

163

147

147

147

131

131

116

116

116

131

084

163

N

5 100

(km)

(o) Dehydrogenase

107∘45

998400E 107∘55

998400E

521

465

576

409

354

632

465

465

409

521

521

465

465

465

521

521

521

5 100

(km)

N

(p) TEI




















2119875

Orchard(119899 = 75)



10Total P 0491 lt0001



10Total P 0483 lt0001

Cropland(119899 = 170)









Total(119899 = 245)



















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics


















120574 (ℎ) =

1

2119873 (ℎ)

119873(ℎ)

sum

119894=1

[119885 (119909

119894) minus 119885 (119909

119894+ ℎ)]

2

(1)


119894and 119909

119894+ ℎ


119894) and 119885(119909




119885

lowast(119909

0) =

119899

sum

119894=1

120582

119894119885 (119909

119894) (2)


0 119885(119909119894) are the






TEI =119894

sum

119899=1

119883

119894

119883

119894

(119899 = 1 2 3 4 5) (3)


119894is the mean



GME

=


(4)

3 Results



4


4






























0119862

0+ 119862 [119862

0(1198620+ 119862)]100 Rangekm RMSS






4 Discussion



35∘20

998400N

35∘12

998400N

35∘4998400N

N

1241

1241

1316

1316

1316

1392

1392

1165

1090

788

10151241

1165

5 100

(km)

107∘45

998400E 107∘55

998400E

(a) OM

087

087

093

099

099

064

059

070

104 081

081

081

093

093

093

099

093

099

087

087

076

076

076

076

5 100

(km)

N

107∘45

998400E 107∘55

998400E

087

(b) Total N

099

078

078

078

078

078

085

092

085

064

064

078

071

071

043

043

057 057

057

057

050

050

050

760

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(c) Total P

2410

2146

2058

2322

2498

2586

1882

2586

2146

2146

2234

2234

2234

2058

2322

2058

5 100

(km)

N

107∘45

998400E 107∘55

998400E

2322

2234

(d) Total K

35∘20

998400N

35∘12

998400N

35∘4998400N

5129

4616

5641

5641

41033590

7180

7180

7180

6154

6154

6154

6154

6667 6667

5 100

(km)

N

107∘45

998400E 107∘55

998400E

6667


2142

1413

1049

1778

1960866

1596

1231

1231

12311778

1596

1596

1778

1413

1596

1413

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(f) Available P

6230

13311

14771

14771

22068

16230

19149

19149

19149

19149

19149

17690

17690

20608

22068

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(g) Available K

1422

1196

1309

1309

97

1761

1761

1874

1535

1083

1083

10831083

1648

1648

11961196

1422

1761

1196

1422

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(h) CEC

35∘20

998400N

35∘12

998400N

35∘4998400N

2766

4068

2245

4329

3287

3547

3547

3547

3547

3027

3027

3027

3287

3287

3287

3808

3808

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(i) Clay

855

869

826

862

876883

883

883847

847

847

840

840

876

876

876

855

869

869

862

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(j) pH

37583

344 31

344 31

43888

31279

47040

40736

28127

28127

43888

37583

34431

40736

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(k) Invertase

3248

4036

3642

4430

2854

2459

5219

2065

48253642

2854

2854

3642

3642

2854

2854

4036

2459

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(l) Urease

35∘20

998400N

35∘12

998400N

35∘4998400N

107∘45

998400E 107∘55

998400E

3610

3610

3878

3343

4413

2808

2541

4146

2808

3878

3878

3075

3075

3343

3075

3343

5 100

(km)

N

(m) Phosphatase

107∘45

998400E 107∘55

998400E

1039

748865

865

981

1156

923

923

865

748

981

807

807

807

807

1098

748

1098

1098

690

690

N

5 100

(km)

(n) Catalase

107∘45

998400E 107∘55

998400E

131

084 068

100

179

052

163

163

147

116

163

147

147

147

131

131

116

116

116

131

084

163

N

5 100

(km)

(o) Dehydrogenase

107∘45

998400E 107∘55

998400E

521

465

576

409

354

632

465

465

409

521

521

465

465

465

521

521

521

5 100

(km)

N

(p) TEI




















2119875

Orchard(119899 = 75)



10Total P 0491 lt0001



10Total P 0483 lt0001

Cropland(119899 = 170)









Total(119899 = 245)



















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics





































0119862

0+ 119862 [119862

0(1198620+ 119862)]100 Rangekm RMSS






4 Discussion



35∘20

998400N

35∘12

998400N

35∘4998400N

N

1241

1241

1316

1316

1316

1392

1392

1165

1090

788

10151241

1165

5 100

(km)

107∘45

998400E 107∘55

998400E

(a) OM

087

087

093

099

099

064

059

070

104 081

081

081

093

093

093

099

093

099

087

087

076

076

076

076

5 100

(km)

N

107∘45

998400E 107∘55

998400E

087

(b) Total N

099

078

078

078

078

078

085

092

085

064

064

078

071

071

043

043

057 057

057

057

050

050

050

760

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(c) Total P

2410

2146

2058

2322

2498

2586

1882

2586

2146

2146

2234

2234

2234

2058

2322

2058

5 100

(km)

N

107∘45

998400E 107∘55

998400E

2322

2234

(d) Total K

35∘20

998400N

35∘12

998400N

35∘4998400N

5129

4616

5641

5641

41033590

7180

7180

7180

6154

6154

6154

6154

6667 6667

5 100

(km)

N

107∘45

998400E 107∘55

998400E

6667


2142

1413

1049

1778

1960866

1596

1231

1231

12311778

1596

1596

1778

1413

1596

1413

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(f) Available P

6230

13311

14771

14771

22068

16230

19149

19149

19149

19149

19149

17690

17690

20608

22068

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(g) Available K

1422

1196

1309

1309

97

1761

1761

1874

1535

1083

1083

10831083

1648

1648

11961196

1422

1761

1196

1422

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(h) CEC

35∘20

998400N

35∘12

998400N

35∘4998400N

2766

4068

2245

4329

3287

3547

3547

3547

3547

3027

3027

3027

3287

3287

3287

3808

3808

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(i) Clay

855

869

826

862

876883

883

883847

847

847

840

840

876

876

876

855

869

869

862

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(j) pH

37583

344 31

344 31

43888

31279

47040

40736

28127

28127

43888

37583

34431

40736

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(k) Invertase

3248

4036

3642

4430

2854

2459

5219

2065

48253642

2854

2854

3642

3642

2854

2854

4036

2459

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(l) Urease

35∘20

998400N

35∘12

998400N

35∘4998400N

107∘45

998400E 107∘55

998400E

3610

3610

3878

3343

4413

2808

2541

4146

2808

3878

3878

3075

3075

3343

3075

3343

5 100

(km)

N

(m) Phosphatase

107∘45

998400E 107∘55

998400E

1039

748865

865

981

1156

923

923

865

748

981

807

807

807

807

1098

748

1098

1098

690

690

N

5 100

(km)

(n) Catalase

107∘45

998400E 107∘55

998400E

131

084 068

100

179

052

163

163

147

116

163

147

147

147

131

131

116

116

116

131

084

163

N

5 100

(km)

(o) Dehydrogenase

107∘45

998400E 107∘55

998400E

521

465

576

409

354

632

465

465

409

521

521

465

465

465

521

521

521

5 100

(km)

N

(p) TEI




















2119875

Orchard(119899 = 75)



10Total P 0491 lt0001



10Total P 0483 lt0001

Cropland(119899 = 170)









Total(119899 = 245)



















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics















35∘20

998400N

35∘12

998400N

35∘4998400N

N

1241

1241

1316

1316

1316

1392

1392

1165

1090

788

10151241

1165

5 100

(km)

107∘45

998400E 107∘55

998400E

(a) OM

087

087

093

099

099

064

059

070

104 081

081

081

093

093

093

099

093

099

087

087

076

076

076

076

5 100

(km)

N

107∘45

998400E 107∘55

998400E

087

(b) Total N

099

078

078

078

078

078

085

092

085

064

064

078

071

071

043

043

057 057

057

057

050

050

050

760

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(c) Total P

2410

2146

2058

2322

2498

2586

1882

2586

2146

2146

2234

2234

2234

2058

2322

2058

5 100

(km)

N

107∘45

998400E 107∘55

998400E

2322

2234

(d) Total K

35∘20

998400N

35∘12

998400N

35∘4998400N

5129

4616

5641

5641

41033590

7180

7180

7180

6154

6154

6154

6154

6667 6667

5 100

(km)

N

107∘45

998400E 107∘55

998400E

6667


2142

1413

1049

1778

1960866

1596

1231

1231

12311778

1596

1596

1778

1413

1596

1413

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(f) Available P

6230

13311

14771

14771

22068

16230

19149

19149

19149

19149

19149

17690

17690

20608

22068

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(g) Available K

1422

1196

1309

1309

97

1761

1761

1874

1535

1083

1083

10831083

1648

1648

11961196

1422

1761

1196

1422

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(h) CEC

35∘20

998400N

35∘12

998400N

35∘4998400N

2766

4068

2245

4329

3287

3547

3547

3547

3547

3027

3027

3027

3287

3287

3287

3808

3808

5 100

(km)

N

107∘45

998400E 107∘55

998400E

(i) Clay

855

869

826

862

876883

883

883847

847

847

840

840

876

876

876

855

869

869

862

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(j) pH

37583

344 31

344 31

43888

31279

47040

40736

28127

28127

43888

37583

34431

40736

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(k) Invertase

3248

4036

3642

4430

2854

2459

5219

2065

48253642

2854

2854

3642

3642

2854

2854

4036

2459

N

5 100

(km)

107∘45

998400E 107∘55

998400E

(l) Urease

35∘20

998400N

35∘12

998400N

35∘4998400N

107∘45

998400E 107∘55

998400E

3610

3610

3878

3343

4413

2808

2541

4146

2808

3878

3878

3075

3075

3343

3075

3343

5 100

(km)

N

(m) Phosphatase

107∘45

998400E 107∘55

998400E

1039

748865

865

981

1156

923

923

865

748

981

807

807

807

807

1098

748

1098

1098

690

690

N

5 100

(km)

(n) Catalase

107∘45

998400E 107∘55

998400E

131

084 068

100

179

052

163

163

147

116

163

147

147

147

131

131

116

116

116

131

084

163

N

5 100

(km)

(o) Dehydrogenase

107∘45

998400E 107∘55

998400E

521

465

576

409

354

632

465

465

409

521

521

465

465

465

521

521

521

5 100

(km)

N

(p) TEI




















2119875

Orchard(119899 = 75)



10Total P 0491 lt0001



10Total P 0483 lt0001

Cropland(119899 = 170)









Total(119899 = 245)



















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics
































2119875

Orchard(119899 = 75)



10Total P 0491 lt0001



10Total P 0483 lt0001

Cropland(119899 = 170)









Total(119899 = 245)



















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics





















5 Conclusion








Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics




















Acknowledgments


References



















































Journal of












Volume 2014

Advances in









Geophysics








































Journal of












Volume 2014

Advances in









Geophysics














research article county-scale spatial distribution of soil enzyme … · 2019. 7. 31. · research...

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