Csilla Farkas

Seasonal changes of hydraulic properties of a Chromic Luvisol under different soil management

In the present work the effect of five tillage methods on the hydraulic properties and water regime of a brown forest soil was studied. In each treatment, measurements of bulk density and soil water retention characteristics were carried out 3 times (March, June and August) within the vegetation period. Near-saturated hydraulic conductivity and soil water content measurements were performed five and eight times, respectively. Statistically valuable differences were obtained between the soil properties, measured in different tillage treatments. The effect of the tillage treatments on the water retention curves was significant in the low suction range (pF < 2.0) only. Differences between the soil water retention curves, measured at the end of the vegetation period reflected the indirect effect of different tillage systems on soil hydraulic properties. The seasonal variability of both the soil hydraulic functions was proofed. Saturated hydraulic conductivity values, evaluated in the ploughing treatment at the beginning and end of the vegetation period differed up to 4-times. The near-saturated hydraulic conductivity values measured in March were nearly two times higher in all the treatments, except no till, than those, measured in August. The applied tillage systems did not influence the potential amount of water available for the plant; still, valuable differences between the soil water contents were measured. According to the soil hydraulic properties and measured soil water regime, ploughing and deep loosening created the most favourable soil conditions for the plants. The biological activity, however, was the highest in the no till treatment. Further studies on the application of the soil conserving tillage systems under Hungarian conditions are recommended.

Modelling impacts of different climate change scenarios on soil water regime of a Mollisol

The increase in atmospheric CO2, along with increase in other greenhouse gases, is believed to be changing the earths energy balance (Haskett et al, 2000). There has been recent confirmation of anthropogenic changes in earths climate related to this increase (IPCC, 2001). Climate, hydrology and vegetation are closely linked at local, regional and global scales. Hence, climate and atmospheric composition are likely to have important effects on agriculture (Kovacs and Dunkel, 1999). Consequently, studies on the influence of possible climate change scenarios on the water balance of a stand are important. Simulation models that are able to integrate the influence and relationship of different factors (Flachner et al., 2004) play an important role in studying the effect of different climate and atmospheric gas composition change scenarios on soil water regime and crop development. These studies,

Soil tillage systems to reduce the harmful effect of extreme weather and hydrological situations

Soil as the largest potential natural water reservoir in the Carpathian Basin has increasing importance under conditions of predicted climate change resulting in increase of probability of extreme hydrological events. Soil management changes soil structure and has a major effect on soil water, heat and nutrition regimes. In this study the effect of four tillage treatments in combination with catch crop management was studied on soil hydraulic properties and water regime under semi-arid conditions. Investigations were carried out in a long-term soil tillage experiment established on Calcic Chernozem soil in Hungary. Tillage variants comprised mouldboard ploughing, disking, loosening combined with disking and direct drilling. The crop sequence between September 2003 and September 2004 comprised maize (main crop), rye (catch crop) and pea (forage). In May 2004, disturbed samples and undisturbed soil cores were collected from each tillage treatment/catch crop combination. The main soil physical and hydrophysical properties were determined in laboratory. In each treatment, capacitive soil moisture probes were installed up to 80 cm depth to ensure continuous measurement of soil water content. Total soil water amounts of chosen soil layers and soil water content dynamics as a function of depth were evaluated for selected periods in order to quantify the effect of the studied management systems on soil water regime. The main conclusion from the experiment is that under such (or similar) ecological conditions, the uniform, „over-standardized“ adaptation of tillage methods for soil moisture conservation is rather risky, their application needs special care and the future is for site-specific precision technologies. These are, in combination with catch crop application can be efficient measures of environmental protection and soil structure and water conservation.

Impact of expected climate change on soil water regime under different vegetation conditions

A mathematical model was applied for the Bükk Mountains (Hungary) to evaluate the effects of climate change on soil water balance elements and soil water regime. Model runs using SWAP model were performed for combinations of four distinctive soil types and three land use systems of arable land, grassland, and forest. The temporal variation of soil water regime under changing climatic conditions was examined considering no land cover change occurring in the future. The climate data consisted of the predictions of two regional climate models, the Swiss CLM and the Swedish RCA. The RCA results showed 45% to 50% and the CLM showed 5% to 14% higher future precipitation outlook compared to present conditions. Considering different land use types, the projected number of days with soil moisture deficit was the highest in forest ecosystems for both the upper 50 cm soil layer and the whole soil profile, which could be as high as 61% of days below optimal soil water content range. Our results showed increased water fluxes, especially in deep percolation in far future period and a strong influence of soil properties on the changes in the climate model results, indicating significant long-term effects of climate change on soil water regime.

Water cycle of different wheat genotypes under different water stresses

Introduction Plants are exposed to a large variety of biotic and abiotic stress effects, which limit their productivity (Hegedus et al., 2004). In vitro selection for stress tolerance has a significant importance in the strategy of establishing plant systems with optimal stress reaction and productivity. In the glasshouse stress diagnostic systems a large number (hundreds) of pots are used, therefore the precise and continuous monitoring of soil water content and the other elements of soil water balance would be very expensive and time-consuming. In Hungary, drought is one of the most important constrains of biomass production (Varallyay, 2005, Varallyay, 2006). Hence, it is essential to generate drought stress tolerant wheat genotypes to ensure sustainable and productive wheat production under changed climate conditions. The aim of the present study was to develop a complex stress diagnostic system based on water balance calculation with smaller pot number to obtain supplementary data that would help the operation of the glasshouse stress diagnostic system operated at the Cereal Research Non-Profit Company and the evaluation of the obtained data. This paper presents the results of the first drought stress experiment that was carried out on two wheat genotypes.

Effects of Land Use and Management on Soil Hydraulic Properties

Abstract Soil hydraulic properties are among the most important parameters that determine soil quality and its capability to serve the ecosystem. Land use can significantly influence soil properties, including its hydraulic conditions; however, additional factors, such as changes in climate (temperature and precipitation), can further influence the land use effects on soil hydraulic properties. In order to develop possible adaptation measures and mitigate any negative effects of land use and climatic changes, it is important to study the impact of land use and changes in land use on soil hydraulic properties. In this paper, we summarize recent studies examining the effect of land use/land cover and the associated changes in soil hydraulic properties, mainly focusing on agricultural scenarios of cultivated croplands and different tillage systems.

Soil carbon dioxide efflux determined from large undisturbed soil cores collected in different soil management systems

The aim of this study was to evaluate a measuring technique for determining soil CO2 efflux from large soil samples having undisturbed structure under controlled laboratory conditions. Further objectives were to use the developed measuring method for comparing soil CO2 efflux from samples, collected in three different soil management systems at various soil water content values. The experimental technique was tested and optimised for timing of sampling by taking air samples after 1, 3 and 6 hours of incubation. Based on the results, the incubation time was set to three hours. The CO2 efflux measured for different soil management systems was the highest in the no-till and the lowest in the ploughing treatment, which was in accordance with measurements on accessible organic carbon for microbes. An increase in CO2 efflux with increasing soil water content was found in the studied soil water content range. Our results indicate that soil respiration rates, measured directly after tillage operations, can highly differ from those measured long after.

Prediction of soil properties with field geo-electrical probes.

The need for more precisely located and measured soil data is increasing because of the importance of plant production and environmental threats affecting lands. There is a wide selection of field instruments available for fast assessment of soil properties. Our objectives were to test different instruments measuring soil electrical properties and to study their ability to predict soil physical and chemical properties. For predictions, multiple regression analyses were used. Prediction certainty was estimated using a jackknifing procedure. According to the results, soil electrical conductivity (EC) could be used as predictor of both soil physical and chemical properties, whereas bulk soil dielectric permittivity or soil water content could predict soil texture only. The determination coefficients between the estimated and measured values were 0.87–0.97 for EC and pH, 0.54–0.62 for humus and water contents, and 0.60–0.88 for texture. We concluded that the contemporary technical achievements provide remarkable opportunity for fast and reliable assessment of soil properties.

Climate sensitivity of soil water regime of different Hungarian Chernozem soil subtypes

In this study the possible effects of two predicted climate change scenarios on soil water regime of Hungarian Calcic Chernozem soils has been investigated. Soil profiles classified as Calcic Chernozem — in total 49 — were selected from the MARTHA soil physical database that incorporates soil data at national scale. These profiles were subdivided into three groups (sandy loam, loam and clayey loam) in accordance with their mechanical composition. Soil water retention curves were scaled separately for each of the three textural groups, using similar media scaling in order to represent the variability of soil hydrophysical data with one parameter, the scaling factor (SF). Reference soil profiles were chosen according to the cumulative distribution function of the scaling factor, six for each textural group. Daily downscaled meteorological data from A2 and B2 climate scenarios of the Hadley Centre (2070–2100) and data from a reference period (RF, 1961–1990) were used in this study to characterize different climatic situations. Nine representative years were selected in case of all the three scenarios, using the cumulative probability function of the annual precipitation sum. Scenario analyses were performed, validating the SWAP soil water balance simulation model for the 18 reference soil profiles and 27 representative years in order to evaluate the expected changes in soil water regime under different from the present (RF) climatic conditions (A2 and B2 scenarios). Our results show that the scaling factor could be used as a climate sensitivity indicator of soil water regime. The large climate sensitivity of the majority of Chernozem soil subtypes water regime has been proven.

Modeling runoff from a small artificially drained agricultural catchment in norway, using the drainmod model

The Skuterud catchment is a small artificially drained agricultural catchment, located in south eastern Norway. The total area of the catchment is 4.5 km2 of which agriculture covers 2.7 km2, forest 1.3 km2 while the rest is occupied by urban area. The main agricultural crops are wheat, barley and oat. Climate change can potentially lead to an increase in the number of freeze/thaw cycles which in addition to the predicted increase in precipitation during the period after the growing season from September – April, might lead to an increase in both the amount of runoff and its intensity, with subsequent adverse effects on erosion and nutrient loss. Models are indispensable tools in the prediction of climate change effects on runoff generation. In this respect, the Drainmod model has been tested on the Skuterud catchment concerning its ability to predict runoff from an artificially drained agricultural catchment under prevailing winter conditions. The results are presented in this paper. If proven successful, the model can be used to predict the long term hydrologic impacts of climate change for the Norwegian conditions.