Search

According to prognoses milder winters with more precipitation, warmer and dry summers, and extreme fluctuations in the precipitation should be expected in the Pannonian region from the 2nd decade of the 21st century. The first aim of this study was to discuss the predicted climate phenomena endangering regional soils and deploying methods of measures in the alleviation steps. Further purposes were presenting examples of soils deterioration to be typical in seasons and to confirm that tillage should be an important tool realising soil preservation solutions in the practice. Considering the predicted climate extremes most of classical beliefs are to be supervised. The effects of the rain stress e.g. washing dust and clay colloids down, surface siltation, soil settlement, extension of the existing compact layer and deteriorating crumb fraction in regional soils are demonstrated. Negative impacts of the drought stress on soils are also presented, among others soil desiccation, unutilised water below serious pan layers, crumb reduction and increased dust and crust formation. The first evidence of the investigation is that climate will more incalculable in the next decades, and for this reason applying mitigation methods is really urgent. The second evidence refers to the soil tillage which could take part in the degree of climate induced damages through soil condition modification.

Determination of soil temperature regimes is important to establish the diagnostic horizons that are used for classification of soils. Temperature regimes are determined according to Soil Taxonomy, and soils are allocated into six regimes. From the agricultural aspect, Croatia is divided into three regions: Pannonian, Mountainous and Adriatic and into nine sub- regions. The present analysis shows the average annual cycle of soil temperatures in the period 1981 - 2010 at depths of 10 and 50 cm. According to the average annual soil temperatures, the soils in Middle and South sub-region of the Adriatic region belong to the category of soils with the Thermic temperature regime, and the soils in other seven sub- regions are classified as soils with the Mesic temperature regime. Furthermore, differences between air temperature and soil temperature have been established. Theory that states that the average annual soil temperature can be roughly determined by adding 1°C to the average annual air temperature, was tested on depths of 10 cm and 50 cm and has not proven to be entirely correct.

Soil reaction is a basic soil parameter, since many processes in the soil depend on it, such as the growth and development of plants. Therefore, the monitoring of soil reaction is very important. Natural and anthropogenic factors have influence on the soil reaction. In this paper the values of soil reaction obtained by measurement the samples in three media: H2O, KCl and CaCl2 are shown. The sampling was conducted at 18 locations on eleven soil types and fifteen lower systematic units. The repetition of measurement in the water solution, expressed through the relative standard deviation, was in the range from 0, 21% to 3, 87%. The minimal repetition of measurement in the KCl solution was 0, 19% and maximal 7, 74%. The repetition of measurement in the CaCl2 solution, expressed through the relative standard deviation, was in the range from 0, 25% to 4, 19%. Values of correlation coefficients belong to the classes: strong, very strong and absolute. The values of correlation coefficients for all measured area are: r=0, 96 for the pH(1M KCl) / pH(H2O) ; r=0, 97 for the pH(1M KCl) / pH(0, 01M CaCl2) and r=0, 99 for the pH(H2O) / pH(0, 01M CaCl2) (absolute correlation). The values of correlation coefficients determined in the acid soils are: r=0, 97 for the pH(1M KCl) / pH(0, 01M CaCl2) and pH(H2O) / pH(0, 01M CaCl2) ; r= 0, 91 for the pH(1M KCl) / pH(H2O) (absolute correlation). In the neutral soils, the correlation coefficient for the pH(1M KCl) / pH(0, 01M CaCl2) is r=0, 69 – strong correlation. The correlation coefficient for the pH(1M KCl) / pH(H2O) is r=0, 80 – very strong correlation. The correlation coefficient for the pH(H2O) / pH(0, 01M CaCl2) is r=0, 92 – absolute correlation. In the alkaline soils, the correlation coefficient for the pH(1M KCl) / pH(0, 01M CaCl2) and pH(1M KCl) / pH(H2O) is r=0, 66 – strong correlation. The correlation coefficient for the pH(H2O) / pH(0, 01M CaCl2) is r=0, 88 – very strong correlation. Differences between pH values measured in KCl and CaCl2 are far more stable in acid soils, than in neutral and alkaline ones, where their variability is very high. Differences between pH values measured in KCl and H2O are more stable than in the first case, and on average are the largest in acid soils, and equal one in neutral and alkaline soils. Differences between pH values measured in H2O and CaCl2 are on average equal, with the lowest variability relative to the other media.

All phases of oil exploitation, from the start of oil-drilling works to construction of the transport system (underground pipeline network) are accompanied by interventions and procedures hazardous to the environment. Although the state-of-the-art technical solutions and modern materials used by INA in all exploitation phases warrant a high level of safety, the possibility of different incidents is unfortunately not fully excluded. Incidents endanger natural resources, primarily soil and water, and may, depending on their severity, jeopardize for a certain length of time the intended use of the land on which the incident occurred, that is, rule out the possibility of its use for plant or livestock production. In the last two decades, the staff members of the Faculty of Agriculture Department of General Agronomy participated in the number of studies dealing with the evaluation of the extent of contamination of soil on which an oil incident occurred and drew up studies and plans for remediation of such soils. The paper presents the results of threeyear-long research on growing winter wheat (Triticum aestivum L.), winter barley (Hordeum vulgare L.) and soybean (Glycine hyspida L.) in pots under different degrees of soil contamination by oil. Research involved monitoring of changes in the soil chemical complex (pH, changes in plant available phosphorus and potassium, content of organic matter); also monitoring of number of plants, achieved yields and studying chemical changes in plant material caused by different degrees of soil contamination.