World Congress of Soil Science Logo 18th World Congress of Soil Science
July 9-15, 2006 - Philadelphia, Pennsylvania, USA
International Union of Soil Sciences

Friday, 14 July 2006

This presentation is part of 99: 1.2B Soil System Behavior in Time - Theater

Country-Scale Changes in Salinity/Sodicity/Alkalinity of Hungarian Soils as Shown by the National Soil Monitoring Network.

Tibor Tóth1, Dalma Kovacs1, and Péter Marth2. (1) Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences, Herman O. u. 15., Budapest, 1022, Hungary, (2) Central Service for Plant Protection and Soil Conservation, Budaörsi út 141-145, Budapest, 1118, Hungary

Soil salinization is one of the major degradation forms. Occurring in natural conditions and also on intensively cropped areas as well, it is a remarkable process that affects some 5-10% of the total surface area of the continents. To follow-up the tendencies of soil degradation processes, monitoring systems have been established in many countries. Soil salinization is a process that might be best characterized by soil monitoring networks, since salt concentration of soils can change rather fast. In this study we used the Hungarian soil monitoring system in order to decide what is the overall tendency of salinization in Hungary in recent years: is there an increase or decrease of soil salt concentration? The first period of monitoring in the system was carried out between 1992 and 2000 by successive sampling of the genetic horizons of the soils. Out of the 1236 sampled soil profiles of the ”Soil Protection Information and Monitoring system” , only the salt-affected soils were selected for this study, making up between 55 and 70 profiles depending on the year. For this study, the 19 national “county-level” administrative units were used to provide the yearly background meteorological (sum of precipitation, average, minimum and maximum temperature, irradiation) and groundwater depth data to accompany the monitored soil salinity data. The study period was characterized by a small average rise of groundwater level all over the country. At a yearly time scale the following significant correlations were found between the soil salt concentration and the background variables of yearly precipitation, temperature, irradiation, groundwater depth: The salt concentration of the first, third and fourth soil horizons showed negative correlation at the 0.05 level with the groundwater depth of the previous year. The salt concentration of the first soil horizon showed positive correlation with the irradiation of the current year at the 0.05 level. The second soil horizon showed positive correlation with the irradiation of previous year at the 0.05 level. Strongest response regarding soil salinity was shown by the second genetic horizon, which is either the second horizon of „1.SOLONCHAK”, or the ”B” horizon of „2.SOLONCHAK-SOLONETZ”, „3.MEADOW SOLONETZ”, „4.MEADOW SOLONETZ TURNING INTO STEPPE FORMATION” „5.SOLOD” and „6.SOLONETZIC MEADOW” soils, where the maximum intensity of salt accumulation is found. Based on the salinity, three groups were distinguished, the group of „SOLONCHAK”-type soils, including the first and second soil types, the group of „MEADOW SOLONETZ” soils, including the third type and the group of „SOLONETZIC” soils including types 4-6. There were differences in the tendency of salinity between the groups, calculated by correlation analysis. Soils belonging to „SOLONCHAK” group showed a decrease of soil salinity by time in their second genetic soil horizon. In the group of „MEADOW SOLONETZ” there was no significant tendency shown by any soil depth. In the group of „SOLONETZIC” soils there was an increase in the soil salinity of the whole profile. These results indicate the strong atmospheric control over soil salinity (the groundwater depth is correlated to the precipitation of the previous year). There are no immediate effects, but rather retarded ones when the salinization is being related to yearly average and cumulative meteorological and groundwater data. Salinization is an active process, the most extreme salt-affected soils are becoming less saline, but the least salt-affected soils showed increasing salt concentration parallel to an increase in groundwater level.

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