Soil enhancements such as biochar (BC) are gaining attention as tools to mitigate climate change and also to promote crop growth. However, biochar use can disrupt soil ecosystems by changing the soil’s physical, chemical, and biological properties. The study aimed to determine how biochar influences soil physical changes such as specific surface area (SSA) and water vapor sorption, and how these conditions affect arbuscular mycorrhizal fungal (AMF) hyphae growth and glomalin production. The study analyzed these factors at different plant phenological phases (i.e., flowering, development of fruit, and ripening of fruit and seed) to better understand the changes within the system while varying biochar amounts. The study also investigated the effect of different soil physical and chemical parameters on mycorrhizal hyphae growth and glomalin production. Four treatments were investigated: 0, 0.5%, 2.5%, and 5.0% (w/w) biochar amended silt loam soil planted with pepper. Soil samples were taken at the beginning and weeks 6, 10, and 12 of the study. The amount of adsorbed water vapor increased with an increasing amount of biochar added to the soils. Compared to control, SSA was significantly higher in all biochar amended treatments based on adsorption data, and only in the highest biochar amended soils for the desorption data at the end of the experiment. The presence of AMF in the roots appeared at week 6 of the experiment and the intensity of AMF root colonization increased with the age of plants. The AMF colonization parameters were significantly lower in BC2.5 compared to all other biochar amended soils. The abundance of intraradical AMF structures was highly correlated with several physicochemical soil parameters, such as SSA, the geometric mean diameter of soil aggregate, soil aggregate sizes, or pH. Glomalin production was negatively correlated with SSA, water vapor adsorption, aggregate stability, aggregate size, total nitrogen, potassium, and organic carbon content of the soil, while positive correlation was observed with bulk density. Increased biochar amount resulted in a significant decrease in glomalin production, concurrent with the age of the plants. Our results highlight the great complexity of interactions between soil physicochemical and biological parameters, and the importance of the time of sampling when biochar is used in soil, as the effects of biochar additions on the plant, soil physical characteristics, and soil microsymbionts vary over time.

This work presents point pedotransfer function (PTF) models of the soil water retention curve. The developed models allowed for estimation of the soil water content for the specified soil water potentials: –0.98, –3.10, –9.81, –31.02, –491.66, and –1554.78 kPa, based on the following soil characteristics: soil granulometric composition, total porosity, and bulk density. Support Vector Machines (SVM) methodology was used for model development. A new methodology for elaboration of retention function models is proposed. Alternative to previous attempts known from literature, theν-SVM method was used for model development and the results were compared with the formerly used theC-SVM method. For the purpose of models’ parameters search, genetic algorithms were used as an optimisation framework. A new form of the aim function used for models parameters search is proposed which allowed for development of models with better prediction capabilities. This new aim function avoids overestimation of models which is typically encountered when root mean squared error is used as an aim function. Elaborated models showed good agreement with measured soil water retention data. Achieved coefficients of determination values were in the range 0.67–0.92. Studies demonstrated usability ofν-SVM methodology together with genetic algorithm optimisation for retention modelling which gave better performing models than other tested approaches.

Optimal water supply of plants is key to high yields. However, irrigation in drier regions must be accompanied by soil conservation. Nationwide planning of irrigation needs spatially exhaustive, functional soil maps, which may support proper recommendations for the different areas. For supporting the Hungarian national irrigation strategy, a series of countrywide functional soil maps was created, which reveal the pedological constraints, conditions and circumstances of irrigation by the spatial modelling of the relevant functional features of the soil mantle. Irrigation can improve productivity, while its negative effects may lead to soil degradation. This paper focuses on threats, the spatial identification of potentially affected areas. The thematic maps spatially model the irrigability and vulnerability of soils. Estimation of salt accumulation hazard, and soil structure degradation risks were targeted. The salinization hazard assessment was carried out by two ways. We applied the steady state concept of critical water-table depth and a more dynamic, process-based method. To estimate soil structural degradation hazard, class-based relationships were developed based on soil profile data of MARTHA 1.0 (Hungarian Detailed Soil Hydraulic Database). Soil type, organic matter content, carbonate content, soil reaction and texture class (USDA) were taken into consideration to develop pedotransfer functions for modelling the correlations between primary soil properties and threats indicators. The new maps can help decision makers to improve land use management, and sustainable agronomy.

The diminishing number, extent and degradation of soda lakes were reported from the lowland area of the Carpathian Basin in the past two decades due to anthropogenic impact and climate change. This study provides a detailed spatio-temporal assessment of a degrading alkaline sodic lake ecosystem (13.5 ha) in Southeast Hungary. It discusses the results of spatially detailed topsoil and vegetation surveys from 2009 and 2018 to understand the changes among the current natural and anthropogenic conditions to support a future possible ecological water management. Habitat mapping and laboratory measurement of EC2.5, soda and calcium carbonate content from 199 topsoil samples provided the basis for the assessment. In 2009 the degradation of the naturalness was observed according to the vegetation survey, and the topsoil parameters reflected steppification, leaching and desalinization. Between 2009 and 2018 the loss in extent of Puccinellia swards and the spread of salt meadow species along the channel continued due to the changing salt content. According to the 2018 snapshot of the topsoil, higher salt (from 0.7 to 1.3 mS/cm) and soda content (from 0.08 to 0.12%), furthermore decreasing CaCO₃ content (from 25.89 to 20.08%) were characteristic, meaning that there was a changing water and salt regime in the lakebed. The past decade was partly favourable in the point that humid years could rehabilitate the natural conditions in certain parts of the lakebed, but they did not prove to be enough to sustain this alkaline sodic lake.