Brigitta Tóth

Water Retention of Salt-Affected Soils: Quantitative Estimation Using Soil Survey Information

Soil water retention (SWR) at −0.1, −33, −1500, and −150000 kPa matric potentials and available water content (AWC) were estimated from information available from 729 horizons of salt-affected soils in the Hungarian Detailed Soil Hydrophysical Database. Soil characteristics of the 1:10,000 scale Hungarian soil maps were used as input parameters. Ordinal and nominal (categorical) variables: texture, organic matter content, calcium carbonate content, soluble salt content, pH, and soil subtype classes of the soil map were used to develop a new prediction method based on the CHAID classification tree. Results of the model development were compared with results using conventional prediction methods (classification tree (CRT) and multiple linear regression (MLR)). Four types of pedotransfer rules were established by classification tree methods. The first rule uses continuous-type input parameters, the second uses soil taxonomical information in addition, the third and fourth one uses categorical-type input parameters. In addition, continuous pedotransfer functions (point estimations) were established as well. Results show that the root mean square error (RMSE) of the developed method is between 1.25 vol% (150000 kPa) and 6.40 vol% (−33 kPa). With the mentioned available input parameters, for salt-affected soils the prediction reliability is similar with categorical and continuous-type information. To predict SWR from categorical-type information the CHAID method is advisable. In the case of continuous-type input parameters MLR is suggested, based on this study. The established hydropedologic methods can be readily used to prepare available water content maps for the topsoil of salt affected soils based on solely soil survey information. Supplemental materials are available for this article. Go to the publishers online edition of Arid Land Research and Management to view the free supplemental file.

Study the estimation possibilities of soil hydraulic conductivity

The most important elements of the soil water regime water retention and hydraulic conductivity are known to play an important role in the fate and transport of organic and inorganic compounds in the soils. They determine the air and water management, biological activity and nutrient management of the soil (Vdrallyay, 2005). The knowledge of the soil hydraulic properties has one of the most important effects on the success of plant production (Baser et al.; 2004, Rajkaine and Szundy, 2004; Farkas et al., 2005). Earlier studies (Mako el al., 2005) proved that soil water retention characteristics can be reliably estimated for soil subtypes using the grouped means of texture and humus content categories of soil maps. In the current work we study predicting possibilities of soil hydraulic conductivity from data of soil maps and cartograms as readily available information. For these studies we used the database of the Hungarian Soil Information and Monitoring System. For estimating of soil hydraulic conductivities we used the TALAJTANonc 1.0 software (Fodor and Rajkai, 2005).

Role of soil properties in water retention characteristics of main Hungarian soil types

Relationship between easily available soil properties and soil water retention at given matric potentials were analysed on brown forest soils, chernozems and meadow soils of Hungarian Detailed Soil Hydrophysical Database (Hungarian acronym: MARTHA). We studied the influence of soil properties displayed on the 1:10000 scale Hungarian soil maps on soil water retention at -0.1, -33, -1500 and -150000 kPa. Continuous (particle size distribution, organic matter content, calcium carbonate content and pH) and category type (ordinal: soil texture, ordinal type information on organic matter content, calcium carbonate content and pH; nominal: soil subtype classes) variables were used in the analyses. The relationships was analysed with random forest method based on conditional inference trees (cforest). Water retention of different soil types was characterized. Importance of soil properties in the prediction of soil water content varies according to soil type and matric potentials.

Particle-size and organic matter effects on structure and water retention of soils

Abstract Water storage and flow in soils are highly dependent on soil structure, which strongly determines soil porosity. However pore size distribution can be derived from soil water retention curve (SWRC). Structural characteristics of cultivated arable fields (693 soil profiles, 1773 samples) and soils covered by treated forest stands (137 soil profiles, 405 samples) were selected from the MARTHA Hungarian soil physical database, and evaluated for expressing organic matter effects on soil structure and water retention. For this purpose the normalized pore size distribution curves were determined for the selected soils, plus the modal suction (MS) corresponding to the most frequent pore size class of the soil. Skewness of soils’ pore size distribution curves are found different. The quasi-normal distribution of sandy soils are transformed into distorted in clayey soils. A general growing trend of MS with the ever finer soil texture was shown. Sandy soils have the lowest average MS values, i.e. the highest most frequent equivalent pore diameter. Silty clay and clay soil textures are characterized by the highest MS values. A slight effect of land use and organic matter content is also observable in different MS values of soils under forest vegetation (’forest’) and cultivated arable land (‘plough fields’). MS values of the two land uses were compared statistically. The results of the analyses show that certain soil group’s MS are significantly different under forest vegetation and cultivation. However this difference can be explained only partly and indirectly by the organic matter of different plant coverage in the land use types.

Evaluating Methods of In‐Field Soil Organic Matter Analysis

Abstract The actual content of the soil organic carbon (SOC) has to be periodically measured for soil classification and nutrient management purposes. Traditional SOC tests are relatively time consuming and costly. A rapid field test would be valuable to delineate soil map units with similar SOC to simplify the process of land evaluation while increasing precision. The objectives of this study were to develop and evaluate a new field measurement technique for the quick assessment of SOC. The new method measures the emitted CO2 concentration 3 min after treatment of the soil sample with acidic potassium (K) permanganate solution. The inorganic carbonate content of the soil is measured separately with the addition of sulphuric acid only. Carbon dioxide concentration from both procedures is measured with a portable infrared gas analyzer. The difference between the concentrations measured after the two separate reactions provide an estimate of SOC. Samples from brown forest soils (ca Hapludalf) (0.19–5.53% SOC) were used for the method development. The correlation coefficient between the SOC determined by the new method and laboratory wet combustion method content was 0.76 for the full range of SOC and 0.81 for the soil samples with less than 20% carbonate.

A talajok mechanikai összetétel vizsgálata pipettás ülepítéses módszerrel: a hazai és a nemzetközi szabvány szerinti eljárások összehasonlítása és konverziója

The particle size distribution (PSD) values obtained for a soil database representing the main Hungarian soil types using the Hungarian standard (MSZ-08-0205-78) and the international standard (ISO/DIS 11277:1994) were compared with the pipette method. The relationship between these PSDs and other physical soil characteristics (upper limit of plasticity according to Arany, water vapour adsorption according to Sik) was also analysed, and a suggestion was made of how these results could be converted into each other. Experience showed that the pre-treatments applied as part of the ISO/DIS method may change the ratio of particle size fractions: there was a significant increase in the clay content, while the silt content decreased to a lesser and the sand content to a greater extent, possibly because some of the particles remain in microaggregate form when the MSZ method is used. The results confirmed the greater accuracy of the ISO/DIS method: the clay contents measured with the ISO/DIS method exhibited stron...