Yield and quality of switchgrass in a long-term experiment on low-productive soils in the Right Bank Forest Steppe of Ukraine
Authors: Prysiazhniuk O. I. , Musich V. V. , Kostyna T. P. , Kononiuk N. O. , Cherniak M. O. , Honcharuk O. M. , Kachura Ye. V. 
Published: June 2024

Purpose. To establish the influence of the elements of the cultivation technology on the yield and quality of switchgrass biomass.
Methods. The research was conducted in 2019–2022 at the Uladivske-Liulyntsi Experimental and Breeding Station of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Agrarian Sciences according to generally accepted methods. Switchgrass variety ‘Morozko’ was grown according to a three-factor field experiment design: factor A: soil deoxidation: 1) without liming, 2) application of lime, 1.6 t/ha; factor B: adsorbent: 1) without adsorbent, 2) application of MaxiMarin granulated, 30 kg/ha; factor B: foliar feeding: 1) without feeding, 2) foliar application of Humifield, 50 g/ha, 3) Gumifield, 50 g/ha + AminoStar, 1.0 l/ha. The adsorbent was introduced two weeks before sowing the crop locally in the rows. Foliar application of fertilizers was carried out in the tillering stage and repeated after two weeks.
Results. According to the results of research on the productivity of switchgrass plantations, it was established that the plants reached their peak productivity in the fourth year of vegetation. If in the third year of cultivation, productivity increased by 60% compared to the second year. In the fourth year, the increase was only 8.94%. This makes it possible to obtain a yield of dry matter of 6.25 t/ha. Soil liming was most effective in the first year of vegetation, when the root system of plants was in the lime application zone, which contributed to the formation of an additional 0.12 t/ha of dry matter. In the fourth year, measures to deoxidize the soil had a more significant impact, increasing the yield by 0.14 t/ha. This effect can be explained by an increase in the level of soil moisture in the last two years, when the amount of precipitation increased to the level of the multi-year rate. In the fourth year of vegetation, the influence of all agrotechnical measures on the productivity of switchgrass plantations increased significantly. The root system of plants actively used the upper soil layers to uptake moisture and nutrients, which increased the effect of liming and the adsorbent.
Conclusions. It was found that combined application of lime and adsorbent MaxiMarin to the soil and foliar application of Humate potassium (Humifield) and the anti-stressor AminoStar, the yield of switchgrass was 6.87 t/ha. In the treatment with soil liming (25% of the need), adsorbent and foliar application of fertilizers, the yield of energy from biomass reached 116.2 GJ/ha. Regarding fiber content, the best results were obtained in the treatment with lime, adsorbent, and foliar feeding: 37.1% in leaves and 44.7% in stems. In the treatment with soil liming, the ash content in the leaves of switchgrass was 9.54%, and in the stems, it was 2.87%, which is 1.91 and 1.41% less than in the treatment without liming. Other factors also provided a decrease in ash content; however, within experimental error. A multiple regression equation was established for predicting the yield of switchgrass depending on the photosynthetic potential and the net productivity of photosynthesis: y = −3.25 + 1.34 PP + 21.0 NPP. All coefficients of the equation are significant at the 5% level of significance, and it explains almost 98% of the variation in the dependent variable.