[Climatic changes and their impact on agriculture]

Possible energy and water balance as well as crop changes in Slovakia are analysed to the year 2025, in connection with expected global warning due to greenhouse gases. Analysis of long-term trends (linear regression method) of potential (E0) and actual (E) evapotranspiration, precipitation (P) and evapotranspiration deficit (E0-E) for 1951-1990 as well as model computations lead to the following conclusions. 1. For the period from 1951 to 1990 potential evapotranspiration increased and precipitation decreased in the southern parts of Slovakia; in the northern half of Slovakia and in the mountaineous regions increasing precipitation and small decrease of potential evapotranspiration predominate. 2. Expected increase of air temperature and simultaneous decrease of precipitation (southern region of Slovakia) will decrease relative air humidity, resulting in increasing saturation deficit and potential evapotranspiration; decrease of the number of days with snow cover will result in increase of short wave radiation balance. 3. As a consequence of the above trends, actual evapotranspiration and soil moisture is expected to decrease in the lowlands of Slovakia. In the mountainous regions, with sufficient yearly precipitation, increase of air temperature, decrease of relative air humidity and decrease of number of days with snow cover will increase potential and actual evapotranspiration without substantial change of soil moisture conditions. 4. In the southern half of Slovakia for every model scenario, a decreasing trend of balance runoff and available soil moisture was recorded. In mountain areas increase of precipitation will increase annual runoff. Impacts of climate changes upon agriculture can be briefly summarised as follows: changes of air temperature assurance, of phenological conditions of plants, of solar radiation assurance of plants for photosynthesis, of agroclimatic production potential, of water (soil moisture) assurance, of winter condition of plants, of CO2 concentration and biomass production, of soil physical and soil chemistry characteristics, of diseases, and of pest and weed occurrence. Climatic changes impact upon agriculture are expected to be complex, partly positive and primarily negative. The projected adaptive measures are as follows: long term strategies in agricultural planning: change in crop cultivation technologies, in agroclimatic regionalisation, and structure of crops and varieties cultivated, in breeding objectives and in plant protection. Agricultural practice: regulation of the water supply considering the expected changes of the hydrological cycle, regulation of water and energy regimes of fields by mulching, improvement of soil fertility from the point of view of sustainable agriculture. The book is meant for agricultural experts, agrometeorologists, geographers, ecologists, teachers and students (higher education degree)