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Pedosphere 2011年第2期21卷 170-177页

作者： h.r.motaghian J.MOhAMMADI Department of Soil Science Agriculture CollegeShahrekord UniversityShahrekord (Iran)

Several methods,including stepwise regression,ordinary kriging,cokriging,kriging with external drift,kriging with varying local means,regression-kriging,ordinary artificial neural networks,and kriging combined with artificial neural networks,were compared to predict spatial variation of saturated hydraulic conductivity from environmental *** methods except ordinary kriging allow for inclusion of secondary *** secondary spatial information used was terrain attributes including elevation,slope gradient,slope aspect,profile curvature and contour curvature.A multiple jackknifing procedure was used as a validation *** mean square error (rMSE) and mean absolute error (MAE) were used as the validation indices,with the mean rMSE and mean MAE used to judge the prediction *** performance by ordinary kriging was poor,indicating that prediction of saturated hydraulic conductivity can be improved by incorporating ancillary data such as terrain *** combined with artificial neural networks performed *** prediction models made better use of ancillary information in predicting saturated hydraulic conductivity compared with the competing *** combination of geostatistical predictors with neural computing techniques offers more capability for incorporating ancillary information in predictive soil *** is great potential for further research and development of hybrid methods for digital soil mapping.

关键词： digital elevation model geostatistics soil hydraulic properties spatial mapping

refining Soil Organic Matter Determination by Loss-on-Ignition

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Pedosphere 2011年第4期21卷 473-482页

作者： M.h.SALEhI O.hAShEMI BENI h.BEIGI hArChEGANI I.ESFANDIArPOUr BOrUJENI h.r.motaghian Department of Soil Science College of AgricultureShahrekord University Department of Soil Science College of AgricultureVali-e-Asr University

Wet oxidation procedure,i.e.,Walkley-Black (WB) method,is a routine,relatively accurate,and popular method for the determination of soil organic matter (SOM) but it is time-consuming,costly and also has a high potential to cause environmental pollution because of disposal of chromium and strong acids used in this ***,loss-on-ignition (LOI) procedure,a simple and cheap method for SOM estimation,which also avoids chromic acid wastes,deserves more *** aims of this research were to study the statistical relationships between SOM determined with the LOI (SOMLOI) and WB (SOMWB) methods to compare the spatial variability of SOM in two major plains,Shahrekord and Koohrang plains,of Chaharmahal-va-Bakhtiari Province,*** surface soil samples (0-25 cm) were randomly collected in each plain to determine SOM using the WB method and the LOI procedure at 300,360,400,500 and 550 ℃ for 2 *** samples covered wide ranges of soil texture and calcium carbonate equivalent (CCE).The general linear form of the regression equation was calculated to estimate SOM LOI from SOM obtained by the WB method for both overall samples and individual *** soil samples were also randomly selected to compare the SOM and CCE before and after ignition at each *** accuracy of the continuous maps generated for the LOI and WB methods was considered to determine the accordance of two *** showed a significant positive linear relationship between SOM LOI and SOM *** of determination (r2) of the equations for individual plains were higher than that of the overall *** of determination and line slopes decreased and root mean square error (rMSE) increased with increasing ignition temperature,which may be due to the mineral structural water loss and destruction of carbonates at higher temperatures.A temperature around 360 ℃ was identified as optimum as it burnt most organic carbon,destroyed less inorganic carbon,cau

关键词： calcium carbonate equivalent ignition temperature kriged maps spatial variability wet oxidation

Application of Kinetic Models in Describing Soil Potassium release Characteristics and Their Correlations with Potassium Extracted by Chemical Methods

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Pedosphere 2013年第4期23卷 482-492页

作者： A. r. hOSSEINPUr h. r. motaghian Department of Soil Science College of Agriculture Shahrekord University

Potassium （K） release characteristics in soil play a significant role in supplying available K. Information on K-release characteristics in soils of central Iran is limited. The objectives of this study were to determine K release characteristics and correlations of K release rate constants with K extracted by different chemical methods in surface soils of ten calcareous soils of central Iran. The kinetics of K release in the soils was determined by successive extraction with 0.01 mol L-1 CaC12 in a period of 2-2017 h at 25±1℃. Soil K was extracted by distilled water, 0.5 mol L-1 MgNO3, 0.002 mol L-1 SrC12, 0.1 mol L-1 BaC12, 0.01 mol L-1 CaC12, 1 mol L-1 NaC1, 1 mol L-1 boiling hNO3, 1 mol L-1 Nh4OAC, Mehlich 1, 0.002 mol L-1 SrC12 ＋ 0.05 mol L-1 citric acid, and ammonium bicarbonate-diethylenetriamine pentaacetic acid （AB-DTPA）. A plot of cumulative amounts of K released showed a discontinuity in slope at 168 h. Thus, two equations were applied to two segments of the total reaction time （2-168 and 168-2 017 h）. Cumulative amounts of K released ranged from 55 to 299 mg kg-1 in 2-168 h and from 44 to 119 mg kg-1 in 168-2 017 h. release kinetics of K in the two time segments conformed fairly well to parabolic diffusion, simplified Elovich, and power function models. There was a wide variation in the K release rate constants. Increasingly higher average concentrations of soil K were extracted by distilled water, Mehlich 1, SrC12, CaC12, SrC12 ＋ citric acid, AB-DTPA, MgNO3, NaCI, Nh4OAc, BaCI2, and hNO3. Potassium release rate constants were significantly correlated with K extracted. The results of this study showed that information obtained from mathematical modeling in two reaction time segments can help to estimate the K-supplying power of soils.

关键词： chemical extraction calcareous soils mathematical modeling release rate constant time segments

Spatial Prediction of Soil Aggregate Stability and Aggregate-Associated Organic Carbon Content at the Catchment Scale Using Geostatistical Techniques

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Pedosphere 2011年第3期21卷 389-399页

作者： J.MOhAMMADI M.h.motaghian Department of Soil Science Agriculture CollegeShahrekord University

The association of organic carbon with secondary particles （aggregates） results in its storage and retention in soil. A study was carried out at a catchment covering about 92 km2 to predict spatial variability of soil water-stable aggregates （WSA）, mean weight diameter （MWD） of aggregates and organic carbon （OC） content in macro.- （〉 2 mm）, meso- （1-2 mm）, and micro-aggregate （〈 1 mm） fractions, using geostatistical methods. One hundred and eleven soil samples were eSlleeted at the 0 10cm depth and fractionated into macro-, meso-, and mlcro-aggregates by wet sieving. The OC content was determined for each fraction. A greater percentage of water-stable aggregates was found for micro-aggregates, followed by meso-aggregates. Aggregate OC content was greatest in meso-aggregates （9 g kg-1）, followed by micro-aggregates （7 g kg-1）, while the least OC content was found in macro-aggregates （3 g kg-1）. Although a significant effect （P = 0.000） of aggregate size on aggregate OC content was found, however, our findings did not support the model of aggregate hierarchy. Land use had a significant effect （P = 0.073） on aggregate OC content. The coefficients of variation （CVs） for OC contents associated with each aggregate fraction indicated macro-aggregates as the most variable （CV = 71%）. Among the aggregate fractions, the micro-aggregate fraction had a lower CV value of 27%. macro-aggregates to 84% for micro-aggregates. Geostatistical analysis differences in their spatial patterns in both magnitude and space at variance for most aggregate-associated properties was lower than 45%. The mean content of WSA ranged from 15% for showed that the measured soil variables exhibited each aggregate size fraction. The relative nugget The range value for the variogram of water-stable aggregates was almost similar （about 3 km） for the three studied aggregate size classes. The range value for the variogram of aggregate-associated OC contents ranged from about 3 km for macro-aggregates to about

关键词： kriging organic matter variogram water-stable aggregates

Effects of sugarcane residue biochar and P fertilizer on P availability and its fractions in a calcareous clay loam soil

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Biochar 2020年第3期2卷 357-367页

作者： Mina Safian hamidreza motaghian Alireza hosseinpur Department of Soil Science College of AgricultureShahrekord UniversityShahrekordIran

Biochar has the potential to affect the cycle of phosphorus(P),but the underlying mechanisms of its effects remain poorly understood in calcareous *** understanding of the effects of biochar is limited in calcareous soils during ***,this study was conducted to investigate how the availability and mineral fractions of P change after the addition of combined biochar and P fertilizer during incubation in calcareous *** residue(raw Sr)and biochar(400℃for 2 h)were added to soils treated with 50 mg kg−1 of P,in the form of Ca(h_(2)PO_(4))_(2)·h_(2)O,at 0.5 and 1%(w/w).The soils were incubated at 25±1℃for 120 *** P(Olsen P)contents and mineral P fractions were measured after various incubation times(7,30,90,and 120 days).Biochar addition remarkably increased the amount of available P when compared with the raw Sr treatment and the control condition(Pr 30 days of incubation,the amount of available P in the soils decreased and remained unchanged *** results indicated that the addition of 50 mg kg−1 of P as fertilizer significantly augmented the labile P and P associated with Fe and Al in all the treatments at all incubation times(Prison with P treated with raw Sr,P associated with Fe and Al was significantly enhanced after biochar addition(Prrelations were found for available P with labile P and P associated with Fe and *** found that biochar addition could increase available pools,thus improving available P concentrations at various incubation ***,we conclude that sugarcane residue biochar can enhance the available P in calcareous soils.

关键词： Organic amendment Incubation time Available pool