PATTERNS OF ENERGY-MASS EXCHANGE IN SOIL-PLANT-ATMOSPHERE ENVIRONMENT UNDER CURRENT CLIMATIC AND ECONOMIC CONDITIONS FOR IRRIGATION
Under climate change it is necessary to review existing approaches to irrigation planning based on the criterion of humidity in the active soil layer in the optimal range and to take into account the regularities of energy-mass exchange processes both in soil and in crops for controlling the microclimate.
In order to achieve this goal, special integrated research was conducted. Two study polygons with a total area of 1012.5 hectares were arranged in the farm in the Kakhovka district of the Kherson region. Polygon №1 - traditional irrigation planning with soil moisture regulation in the range of 75-80-75% FC and 13 waterings with the rate 200-400 m3/ha. Polygon №2 - intensive irrigation with 36 waterings at a rate of 100-200 m3/ha with soil moisture keeping at the level of 80-90% FC.
As a result of research, the following indicators were assessed: weather conditions; microclimatic effect of irrigation; the effect of irrigation on the components of the thermal balance (radiation of the earth's surface, radiation balance of the earth's surface); the dynamics of total evaporation; the dynamics of soil moisture, the state of development of agricultural crops; efficiency of irrigation water use.
The following results were obtained:
- in conditions of prolonged drought at maximum daily air temperatures of 28-36 ° C, the use of an intensive irrigation management scenario provides a more favorable microclimatic effect on crops;
- under intensive irrigation, the humidity of the active soil layer decreases and fluctuates in the range of 82-100% FC. The plant roots absorb moisture mainly to a depth up to 50-centimeter soil;
- regardless of the irrigation management scenario an increase is observed in the absorption of solar energy by the earth's surface and vegetation. It can be explained by the decrease of the soil albedo and the increase in the heat capacity of the soil after watering;
- as a result of irrigation, additional heat flux reaches the earth's surface in the form of effective atmosphere radiation - at the first study polygon up to 13%, at the second – up to 14% of incoming radiation;
- frequent irrigation with small watering rates under intensive irrigation management scenarios contributes to increase the productivity of irrigation water, which is due to the creation of optimal conditions for water use and heat resources.
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