Simulation of lucerne green mass productivity on non-irrigated and irrigated lands under climatic changes

Abstract

Goal. TTo evaluate the results of mathematical modeling of the productivity of crops and yield of green mass of lucerne on southern heavy-clay chornozem according to the RCP8.5 scenario of climatic changes in non-irrigated and irrigated conditions of the Southern Steppe of Ukraine. Methods. The RCP8.5 scenario of climate change — to predict the water-thermal regime, mathematical modeling — to conduct numerical calculations, and analysis of the research results. Results. They expect that during the research period in 2031 – 2050 on non-irrigated lands of the Southern Steppe in the I hay crop period, there will be good agro-climatic conditions that will contribute to the formation of green mass yields at the level of 27.9 t/ha. In the II hay crop period, due to an increase in air temperature (average maximum temperature — 30.3 versus 21.8 °C), and a decrease in precipitation (65 versus 113 mm), the yield will be 16.4 tons/ha. Very hot conditions (an increase in the average maximum temperature to 34.6 °C, a decrease in precipitation to 20 mm) of the III hay crop period will contribute to a yield of only 2.3 tons/ha. On irrigated lands, with the maintenance of productive moisture reserves at the level of 75% of NV in the soil layer of 0 – 100 cm thick, the yield in all 3 periods will increase: 1st hay crop — up to 30.0 t/ha, 2nd — up to 32.8 t/ha, 3rd — up to 10.6 t/ha. Conclusions. In the Southern Steppe of Ukraine, on the southern chornozem under the RCP8.5 scenario of climate change in the agro-climatic conditions of the spring-summer growing season of lucerne on non-irrigated lands, there will be losses of the yield of green mass because of severe drought in the II inter-mowing period and very severe drought in the III inter-mowing period (50% and 78% respectively). Growing lucerne on irrigated lands will increase the yield of green mass by 1.5 times; in general, for vegetation, it will be 73.4 tons/ha.