The effect of growth stimulants based on humic acids from Ukrainian lignite and biochar from agricultural residues on the growth and development of lettuce (Lactuca sativa)

M. Zhylina¹²*, P.P. Karnozhytskyi³, D. Miroshnichenko³⁴, V. Konohrai⁵, V. Sterna² and J. Ozolins¹

¹Riga Technical University, Faculty of Natural Sciences and Technology, Institute of Biomaterials and Bioengineering, Paula Valdena Street 3, K-1, LV-1048 Riga, Latvia
²Institute of Agricultural Resources and Economics, Stende Research Centre, Dizzemes, Dizstende, Libagu parish, Talsu County, LV-3258, Latvia
³Department of Oil, Gas and Solid Fuel Processing Technology, National Technical University Kharkiv Polytechnic Institute, 2, Kyrpychova Str., UA 61002 Kharkiv, Ukraine
⁴Coal Department, State Enterprise Ukrainian State Research Institute for Carbochemistry (UKHIN), UA 61023 Kharkov, Ukraine
⁵Education-Scientific Institute of Natural and Agrarian Sciences, the Bohdan Khmelnytsky National University of Cherkasy, 81 Shevchenko Boulevard, UA 18031 Cherkasy, Ukraine
*Correspondence: maryna.zhylina@gmail.com

Abstract:

Significant amounts of plant-based waste are generated annually in the agricultural and food industries, including straw, corn residues, nutshells, and fruit pits. Disposing of this waste often relies on basic methods that avoid further processing, presenting an urgent environmental challenge. One efficient solution is converting biomass into biochar, which serves as a soil amendment. Developing cost-effective recycling methods has become critical with the increasing scarcity and rising cost of raw materials. The Dnipro Lignite Coal Basin in Ukraine offers extensive lignite reserves, enabling the production of affordable, high-quality humates for soil enhancement. In this study, wheat and barley straw were pelletized with barley bran at a 90:10 ratio. Pyrolysis was conducted at 500 °C with a heating rate of 5 °C·min⁻¹ and a one-hour holding time. The resulting biochar was added to a lettuce cultivation substrate at a 1:10 biochar-to-peat ratio. Humic substances derived from lignite were applied in 3% and 9% aqueous solutions, and environmental conditions, such as humidity and temperature, were monitored throughout the 35-day trial. Results showed that granulated biochar increased lettuce rosette diameter by 7.5% compared to perlite substrates and by 11.6% compared to peat. Additionally, 3% humate solutions enhanced rosette diameter by 11.6% and biomass weight by 25.77%. These findings confirm that biochar from agricultural residues and lignite-derived humates effectively boost lettuce yield and quality.

Key words:

agricultural residues, Agro-ecology, biochar, biomass, carbon cycle, crop, growth stimulants, Lactuca sativa, lignite-derived humates, renewable resources, soil quality

Influence of organic and inorganic fertilization on soil properties and water infiltration

M. Stehlík¹²*, A. Czako¹, M. Mayerová¹ and M. Madaras¹

¹Division of Crop Management Systems, Crop Research Institute, Drnovská 507, CZ 16106 Prague, Czech Republic
²Department of Agricultural Machines, Czech University of Life Sciences, Kamýcká 129, CZ 16521 Prague, Czech Republic
*Correspondence: martin.stehlik@vurv.cz

Abstract:

Soil aggregate stability (SAS) belongs to the most important parameters determining the quality of soil and fertilizer influence on soil aggregation. We evaluated the relationship between SAS, hydro–physical soil properties and infiltration rates in three long–term field experiments founded in 1956 on different soils. Soil properties under three fertilization regimes–no fertilization, farmyard manure, farmyard manure and mineral fertilization–were evaluated at silty loam Chernozem, silty loam Phaeozem and sandy loam–loam Cambisol. A significant impact of fertilization on SAS was found, even though the differences in SAS were rather low. The lowest SAS was recorded at plots with manure and mineral fertilization (25.1%) compared with plots without fertilization (28.7%) and plots with manure–only fertilization (28.2%). The highest SAS (36.5%) and the highest semi–capillary porosity (SP; 11%) were observed at sandy loam–loam soil. Hydro–physical soil properties were more favourable at fertilized plots (SP 9.6% and bulk density ρ_b 1.31 g cm^-3) compared with unfertilized ones (SP 8.8% and ρ_b 1.35 g cm^-3). The lowest SP (8.32%) and the highest ρ_b (1.37 g cm^-3) were recorded at Phaeozem, which corresponded with the lowest SAS (19.4%). Chernozem had similar soil texture to Phaeozem, but SAS (24.7%), SP (9%) and ρ_b (1.27 g cm^-3) were more favourable. Despite the low level of statistical significance due to the large variation of infiltration measurements, a higher infiltration rate was recorded at fertilized plots (45 mm hour^-1) compared to unfertilized ones (35 mm hour^-1).

Key words: