ADAPTING THE PENMAN-MONTEITH METHOD TO TRASPLANTED TOMATO CROP IN PRODUCTION CONDITIONS WHEN APPLYING DRIP IRRIGATION

The relevance of the research. Tomato is considered to be a strategic vegetable crop in Ukraine. This crop is cultivated in a large area covering more than 80 thousand hectares, and the gross annual harvest is more than 1.5 million tons. The largest producer of tomatoes in Ukraine is Agrofusion Company, which grows 600 thousand tons in the area of 5600 hectares. The fields of the company are equipped with drip irrigation systems; therefore the issue of efficient management of soil water regime in these conditions is relevant. The purpose of the research is to investigate the features and to adapt the existing Penman-Monteith method for determining total evaporation to the conditions of the Steppe of Ukraine under drip irrigation. Research methods: field short-term experiments, conventional analytical methods; methods of dispersion, correlation, regression and variation analyses were used. The scientific-methodical approaches were substantiated and the need for adapting the «Penman-Monteith» method to the tomato crop was proved. Research results. Using the modern tools (internet weather-stations iMETOS®, soil moisture stations iMetos® ECOD2) the benchmark ETo was determined and the actual values of total evaporation ЕТс were calculated. Based on the results of field experiments the adjustment of crop coefficient Kc was carried out by the development phases of tomato plants using the deviations from the standard conditions. The regime of drip irrigation and the parameters of tomato ETс in the production conditions of the Steppe of Ukraine were determined. The actual coefficients of tomato Kc were calculated, in view of the climatic conditions of the Steppe zone of Ukraine. It was proved that the actual values Kc are lower by 40,9-43,5 % than Kc provided by FAO. It is recommended in the future to use the adjusted crop coefficient for determining ETc and operative management of drip irrigation regime for tomato crops. Conclusions. The features were investigated and the existing Penman-Monteith method for determining total evaporation when applying drip irrigation in the Steppe of Ukraine was adapted.