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Although it has been recognized that the adsorption of organics to clay and silt particles is an important determinant of the stability of organic matter in soils, no attempts have been made to quantify the amounts of C and N that can be preserved in this way in different soils. Our hypothesis is that the amounts of C and N that can be associated with clay and silt particles is limited. This study quantifies the relationships between soil texture and the maximum amounts of C and N that can be preserved in the soil by their association with clay and silt particles. To estimate the maximum amounts of C and N that can be associated with clay and silt particles we compared the amounts of clay-and silt-associated C and N in Dutch grassland soils with corresponding Dutch arable soils. Secondly, we compared the amounts of clay-and silt-associated C and N in the Dutch soils with clay and silt-associated C and N in uncultivated soils of temperate and tropical regions. We observed that although the Dutch arable soils contained less C and N than the corresponding grassland soils, the amounts of C and N associated with clay and silt particles was the same indicating that the amounts of C and N that can become associated with this fraction had reached a maximum. We also observed close positive relationships between the proportion of primary particles < 20 µm in a soil and the amounts of C and N that were associated with this fraction in the top 10 cm of soils from both temperate and tropical regions. The observed relationships were assumed to estimate the capacity of a soil to preserve C and N by their association with clay and silt particles. The observed relationships did not seem to be affected by the dominant type of clay mineral. The only exception were Australian soils, which had on average more than two times lower amounts of C and N associated with clay and silt particles than other soils. This was probably due to the combination of low precipitation and high temperature leading to low inputs of organic C and N. The amount of C and N in the fraction > 20 µm was not correlated with soil texture. Cultivation decreased the amount of C and N in the fraction > 20 µm to a greater extent than in the fraction < 20 µm, indicating that C and N associated with the fraction < 20 µm is better protected against decomposition. The finding of a given soil having a maximum capacity to preserve organic C and N will improve our estimations of the amounts of C and N that can become stabilized in soils. It has important consequences for the contribution of different soils to serve as a sink or source for C and N in the long term.

The effect of erosion and erosion control measures on changes in the amount of organic matter in soil was studied. We investigated the influence of organic matter inputs into the soil on surface runoff, soil erosion and soil erodibility (K-factor), including the monitoring of carbon dynamics, as a result of torrential rains. The research was conducted on experimental plots in Třebsín site. Erosion leads to soil carbon loss and subsequently to increasing concentrations of carbon in sediments (enrichment ratio). We can conclude from the results that the input of organic matter into the soil (especially farmyard manure) significantly contributes to a decrease in surface runoff and soil loss and also to a reduction of carbon leaching into sediments; so it contributes to carbon sequestration into the soil.

The database of soil hydrophysical properties in the Czech Republic called HYPRESCZ was created. It is based on the European database HYPRES, HYdraulic PRoperties of European Soils, and follows its structure with few modifications. It collects the available data from the Czech Republic from which pedotransfer functions (PTFs) for the estimation of soil hydrophysical properties from easily available soil properties can be derived and 2101 database entries were collected. The entries have different quality of data, out of the total number of entries 707 entries were applicable to PTFs derivation for the estimation of soil water retention curves (SWRCs). After elimination of replicates, finally 159 unique soil horizons (arable land only) were used for PTFs derivation. The parametric continuous pedotransfer functions for estimation of SWRCs in the Czech Republic were derived within this study and are based on Wösten’s model. The retention curves were estimated using both these newly derived PTFs and Wösten’s original model, which was derived for European soils in general. The uncertainty of estimation was evaluated, employing the root mean squared error (RMSE) and the coefficient of determination (R2) comparing the PTF-estimated and the directly fitted retention curves. The reliability of the newly derived PTFs for Czech soils was higher (RMSE = 0.059 cm3/cm3 and R2 = 71%) compared to Wösten’s general PTFs (RMSE = 0.11 cm3/cm3 and R2 = 36%).

The effects of three different ages of natural fallow vegetation on runoff and sediment loss were investigated in a part of the rainforest zone of Nigeria. Measurements of runoff amount and sediment loss were made for the months of March to November in 2012 rainy season using runoff plots of 40 m2. The average runoff amount for the 5-year-old, 3-year-old, and farmland plots were 0.47, 0.26, and 0.41 mm respectively. The average sediment loss on the 5-year-old, 3-year-old, and farmland plots were 209.24, 50.54, and 124.68 kg/ha, respectively. The lowest losses for both runoff and sediment were recorded on the 3-year-old plot, while the 5-year-old plot experienced the highest losses. The variations in runoff and sediment loss among the treatments were significant at P < 0.001. The results evidently showed that rainfall was principally responsible for the erosional losses on all the fallow treatments, and that ground cover (density of herbs) and girth helped to reduce sediment loss on the 3-year-old and farmland surfaces, respectively. The high amount of erosional losses experienced on the 5-year-old fallow than on the 3-year-old fallow and farmland plots imply that fallow that is not adequately protected by ground cover experiences accelerated soil erosion. The continuous loss in topsoil rich in plant nutrients may prolong the optimal capacity of the soil to regain its loss nutrient for subsequent food crop cultivation.

We tested the performance of a formalized digital soil mapping (DSM) approach comprising fuzzy k-means (FKM) classification and regression-kriging to produce soil type maps from a fine-scale soil observation network in Rišňovce, Slovakia. We examine whether the soil profile descriptions collected merely by field methods fit into the statistical DSM tools and if they provide pedologically meaningful results for an erosion-affected area. Soil texture, colour, carbonates, stoniness and genetic qualifiers were estimated for a total of 111 soil profiles using conventional field methods. The data were digitized along semi-quantitative scales in 10-cm depth intervals to express the relative differences, and afterwards classified by the FKM method into four classes A–D: (i) Luvic Phaeozems (Anthric), (ii) Haplic Phaeozems (Anthric, Calcaric, Pachic), (iii) Calcic Cutanic Luvisols, and (iv) Haplic Regosols (Calcaric). To parameterize regression-kriging, membership values (MVs) to the above A–D class centroids were regressed against PCA-transformed terrain variables using the multiple linear regression method (MLR). MLR yielded significant relationships with R2 ranging from 23% to 47% (P < 0.001) for classes A, B and D, but only marginally significant for Luvisols of class C (R2 = 14%, P < 0.05). Given the results, Luvisols were then mapped by ordinary kriging and the rest by regression-kriging. A “leave-one-out” cross-validation was calculated for the output maps yielding R2 of 33%, 56%, 22% and 42% for Luvic Phaeozems, Haplic Phaeozems, Luvisols and also Regosols, respectively (all P < 0.001). Additionally, the pixel-mixture visualization technique was used to draw a synthetic digital soil map. We conclude that the DSM model represents a fully formalized alternative to classical soil mapping at very fine scales, even when soil profile descriptions were collected merely by field estimation methods. Additionally to conventional soil maps it allows to address the diffuse character in soil cover, both in taxonomic and geographical interpretations.

The relation between soil erosion and its redistribution on land strictly depends on the process of surface runoff formation during intensive rainfall. Therefore, interrupting and reducing continuous surface runoff, using adequate conservation measures, may be implemented in order to reduce the shear stress of flowing water. This paper describes the outcomes of the KINFIL model simulation in assessing the runoff from extreme rainfall on hill slopes. The model is a physically based and parameter distributed 3D model that was applied at the Třebsín experimental station in the Czech Republic. This model was used for the first time to simulate the impact of surface runoff caused by natural or sprinkler-made intensive rains on four of the seven different experimental plots. The plots involved in the analysis contain a variety of soils which are covered with different field crops. At this stage, the model parameters comprise saturated hydraulic conductivity, field capacity, sorptivity, plot geometry and surface roughness reflecting the Třebsín experimental plots. These parameters were verified on observed data. All seven plots had the same slope angle, but two of them were vulnerable to surface runoff due to their soil hydraulic parameters. There were rapidly increasing depths and velocities which consequently caused a higher shear stress for splashing soil particles downstream. The paper provides further information and data concerning the relationships between the depth of water and its velocity on the slopes of certain roughness. It also provides information concerning shear stress and shear velocity values, compared with their critical values depending on the soil particle distribution. This approach is more physically based than the traditional method of Universal Soil Loss Equation (USLE).

One of the key goals of the Thematic Strategy for Soil Protection is to maintain and improve soil organic carbon (SOC) stocks. A decline of SOC stocks is politically perceived as a serious threat to soil quality and functions. A suitable tool for acquiring the information on SOC stock changes is modelling. The RothC-26.3 model was applied for long-term modelling (1970–2007) of the SOC stock in the topsoil of croplands of Slovakia. Simulation results show a gradual increase in the SOC stock in the first phase of modelling (1970–1995) mainly due to higher carbon input in the soil. A significant linear correlation (r = 0.4**, n = 275) was found between carbon input and the final simulation of SOC stock. A close relationship between the SOC stock and soil production potential index representing the official basis for soil quality assessment in Slovakia was also determined and a polynomial relationship was found which describes the relation at the 95% confidence level. We have concluded from the results that balanced or positive changes in the SOC stock dynamics that are important for sustainable use of soils could be influenced positively or negatively in Slovakia by political decisions concerning the soil management. Moreover, the soil production potential index can be used as soil quality information support for such decision-making.

The aim of our work was to characterise the stability, humification degree, and principal classes of fluorophores in humic acids isolated from different matrices. Soil humic acids were isolated from arable soils and grassland that differ in the texture and moisture regimes (e.g. aquic; udic; and ustic moisture regimes). Basic soil characteristics, such as total organic carbon content, humus fractionation, cation exchange capacity, soil reaction, texture, and optical indexes were determined. The international standard method for humic acids (HA) isolation was used. Lignite represents a valuable organic substrate, with mineral inclusion situated on the transformation route from phytomass to a dehydrated, dehydrogenated, and deoxidised carbon type complex and water. One of the most attractive ways of non-energetic exploitation of lignite is humic substances source exploitation. It is known that humic acids isolated from lignite show typical bands known from other HA soil samples due to aromatic and various C-O structures. Spectroscopic characterisation has been a topic of great interest, chemical species being analysed with respect to the overall spectral characteristics of the system. Therefore UV-VIS, FTIR, and synchronous fluorescence spectroscopy (SFS) were applied in our study. The elemental composition and ash content in HA samples were determined. HA preparations were more hydrated in hydromorphic soils (Fluvi-Eutric Gleysol and Gleyic Stagnosol). The highest carbon content was found in lignite HA (57.5 weight %). Generally, carbon content was decreasing in the following order: Lignite HA > Haplic Chernozem HA > Fluvi-Eutric Gleysol HA > Haplic Luvisol HA > Gleyic Stagnosol HA > Eutric Cambisol HA. FTIR spectroscopy showed that the aromatic indexes varied from 0.61 to 0.73. HA were divided into two groups according to the aromatic and aliphatic compounds in their molecules. The highest aromatic degree and stability was found in lignite HA and Haplic Chernozem HA. Humic acids isolated from grassland and hydric soils contained more aliphatic and newly formed compounds. Synchronous fluorescence scan spectra identified aliphatic compounds in grassy and hydric soils at lower wave lengths. At higher wave lengths, identical fluorophores were detected. We registered five main peaks at: 467/487, 481/501, 492/512, 450/470, 339/359 (at Δλ = 20 nm). The peaks positions corresponded to the fluorescence behaviour of Elliot soil HA standard. Only lignite HA revealed another fluorescence peak at 492/512 nm. The peaks positions complied with the fluorescence behaviour of Leonardite standard HA. The relationships between the fluorescence indexes, colour indexes, aromatic indexes, humification degree, and elemental composition were evaluated by correlation analysis.

Soil microbial communities involved in the cycling of nitrogen (N) are essential to maintaining and improving soil fertility, productivity and functionality of natural and agricultural ecosystems. However, some compounds generated during the metabolic processes performed by nitrifying (NB) and denitrifying (DB) bacteria are associated with the production of greenhouse gases, groundwater pollution and acidification. Therefore, the study of these bacteria is essential for economic and environmental sustainability. This study evaluated the effect of different land uses in two river basins (La Vieja and Otún) on NB and DB densities. Two sampling events (SE) were conducted by selecting the most representative land uses. Physicochemical (T °, pH, moisture and nitrate) and microbiological properties (NB and DB densities) were evaluated. In both SEs, significantly higher densities of NB and DB were observed in the land uses: pasture, guadua (DB only) and unshaded coffee (La Vieja) and onion (Otún). These land uses, excluding guadua, are dependent on nitrogen fertilizers, which together with the activities of grazing livestock on pastures may lead to greater availability of substrates for the NB. The use of agricultural machinery and overgrazing in pasture and onion uses generate compacted soil and other physical disturbances, encouraging the growth of DB. Forests had the lowest densities of NB and DB possibly due to a reduced availability of N and the releasing of allelopathic compounds from certain plants. Finally, the densities of ammonium-oxidizing bacteria had the greatest differences between the land uses evaluated, demonstrating its high sensitivity to agricultural management practices and livestock. We suggest that changes in the abundance of this community could serve as a relevant and cost-effective bioindicator for soil monitoring. Key words: nitrifying bacteria, denitrifying bacteria, land use, Colombian coffee region, ammonia oxidizing bacteria. Las comunidades microbianas edáficas involucradas en el ciclaje de nitrógeno (N) son fundamentales para el mantenimiento y mejoramiento de la fertilidad, productividad y funcionalidad de los ecosistemas naturales y agrícolas. Sin embargo, algunos compuestos generados durante los procesos realizados por bacterias nitrificantes (BN) y desnitrificantes (BD), se asocian con la producción de gases efecto invernadero, contaminación de aguas subterráneas y acidificación. Por lo tanto, el estudio de estas bacterias resulta esencial para la sostenibilidad económica y ambiental. El presente estudio evaluó el efecto de diferentes usos de suelo en dos cuencas hidrográficas (la Vieja y Otún) sobre la densidad de BN y BD. Se realizaron dos eventos de muestreo (EM) seleccionando los usos de suelos más representativos. Se evaluaron propiedades fisicoquímicas (T°, pH, porcentaje de humedad y nitratos) y microbiológicas (densidad de BN y BD-Número más probable). En los dos EM se observaron densidades significativamente mayores de BN y BD en los usos de pastizal, guadual (solo BD) y cafetal sin sombrío (la Vieja), así como en cebolla (Otún). Estos usos de suelo, excluyendo guadual, son dependientes de fertilizantes nitrogenados, lo cual en conjunto con las actividades de pastoreo del ganado en los pastizales, podrían generar una mayor disponibilidad de sustratos para las BN. El uso de maquinaria agrícola y sobrepastoreo en cebolla y pastizal generan disturbios físicos en el suelo y lo compactan favoreciendo el crecimiento de BD. Los bosques presentaron las densidades más bajas de BN y BD posiblemente por una menor disponibilidad de N y la liberación de compuestos alelopáticos. Finalmente, las densidades de bacterias oxidadoras de amonio fueron quienes presentaron mayores diferencias entre los diferentes usos de suelo evaluados, demostrando su alta sensibilidad frente a prácticas de manejo agrícola y pecuario. Palabras clave: bacterias nitrificantes, bacterias desnitrificantes, usos de suelo, ecorregión cafetera colombiana, bacterias oxidadoras de amonio.

Soil phosphorus (P) can exist in various inorganic (Pi) and organic forms (Po). Specific determination of Pi can be obtained by fractionate methods. However, the discrimination between the chemically different forms of Po in soil is not simple. Nowadays, the method of choice for the determination of various soil inorganic and organic P compounds is 31P NMR. In this paper, the determination of various phosphorus forms (available P, total P, Pi and Po fractions) in arable and mountain soils is presented. Besides, the detailed characterisation of P compounds in humic acids (HA) is also shown. The results obtained show that the highest content of the available P can be found in arable soils with a high input of fertilisers, and that the predominant part of Pi is included in hardly soluble fractions, mainly in the soil types with neutral soil reaction. Our data also show the correlation between total P and Po, the dominant form of P in the topsoil of mountain soils. Phosphomonoesters represent the major types of P in HA structure. The correlations between phosphomonoesters of type I and some humification parameters of HA and qualitative parameters of soil organic matter suggest that higher amounts of more recalcitrant monoesters can be found in more mature soil organic matter with a higher humification degree.