Turf on humus-containing substrates: water regime of turf-forming grasses in connection with their drought resistance
In the steppe zone, the success of growing turfgrass depends on the temperature and water conditions of the soil and air. In the Dnipropetrovsk region (Dnipro region), the average air temperature in January is -5.7°C, and in July, +22.2°C. In some years, the air temperature in summer rises to +35–40°C, and at the soil surface, to +63–65°C. On average, 240–280 mm of precipitation falls during the growing season, and 400–490 mm annually.
In dry years (2020, 2024), in June–August, soil moisture in drylands was at the level of dead reserves.
Therefore, the vegetation of turf-forming grasses occurs under severe hydrothermal conditions. During periods of intense meteorological factors (July–August), atmospheric drought in the steppe zone is typically accompanied by soil drought. Classic turf-forming grasses of the temperate zone, including red fescue ( Festuca rubra L ), meadow bluegrass ( Poa pratensis L ), creeping bentgrass ( Agrostis stolonifera L ), and several other grasses, are predominantly mesophilic. These grasses exhibit significant ecological plasticity and extensive phytocoenotic ranges, which opens the way to overcoming geographic and ecological imbalances and facilitates the successful expansion of these species into arid regions.
Research in the steppe zone
For several years , the Botanical Garden of Dnipro National University and the modern laboratories of Agro.Bio have been conducting research aimed at identifying native and introduced species that hold promise for creating long-term, drought-resistant turf-forming surfaces. Turf-forming grasses were grown on ordinary, low-humus, silty-light loamy chernozem with a natural moisture regime (Dnipro Botanical Garden), as well as on the third terrace of the leonardite sections of the Orel Canal (Peremoha farm in Dnipro district). The goal was to trace the relationship between the bioecology of promising turf-forming grasses and specific water regime elements.
Plant responses to changing environmental conditions during the summer (June–August) were determined through field observations and laboratory water regime studies. The water-holding capacity of lawn grass leaves was determined using standard specialist methods. Water deficit was calculated as a percentage of the total water content of the leaves after saturation.
Specialists from our laboratory have established that the water content of the leaf tissues of cereal grasses depended on the seasonal hydrothermal conditions and on the biological specificity of the species.
Average values of absolute leaf water content in seasonal dynamics for 2022-2023 and 2024-2025 are presented in Tables 1 and 2. The data show that the range of absolute water content in plants of different ecological groups differs significantly. The absolute minimum leaf water content of 40.7% was observed in the narrow-leaved xeromorphic bunchgrass fescue in August of the dry year 2022. The moisture content in fescue leaves decreased sharply in August of the less dry year 2023 (46.2%), which is associated with the preparation of plants for the summer period of "semi-dormant". The absolute maximum water content in fescue is 69.8%. In mesophytes and mesoxerophytes, the absolute maximum was 78% (white bentgrass) and 72.1–78.3% (crested wheatgrass), respectively. The absolute minimum water content in mesophytes was 52.8% (prairie bluegrass), and in mesoxerophytes, 50.8–56.8% (crested wheatgrass).
Table 1. Absolute water content of lawn grass leaves in seasonal dynamics
(Dnipro Botanical Garden, 2022-2023)
| Types | 2022 (V) | 2022 (VI) | 2022 (VII) | 2022 (VIII) | 2022 (IX) | 2023 (V) | 2023 (VI) | 2023 (VII) | 2023 (VIII) | 2023 (IX) |
|---|---|---|---|---|---|---|---|---|---|---|
| White bentgrass | 75.6 | 68.1 | 64.5 | 64.2 | — | 74.5 | 62.1 | 76.9 | 67.1 | 78.0 |
| Dog's bentgrass | 75.0 | 69.7 | 61.6 | 60.7 | 67.8 | 68.7 | 61.4 | 66.2 | 55.6 | 61.5 |
| Creeping bentgrass | 75.0 | 65.3 | 66.5 | 66.4 | 72.5 | 65.9 | 70.8 | 63.9 | 69.4 | 71.3 |
| Crested wheatgrass | 72.1 | 69.7 | 62.7 | 56.8 | 63.8 | 71.0 | 68.4 | 65.4 | 62.3 | 65.8 |
| Fescue | 66.0 | 57.0 | 55.7 | 40.7 | 69.8 | — | 62.0 | 65.6 | 46.2 | 54.0 |
| Red fescue | 66.9 | 70.6 | 64.0 | 64.0 | 63.0 | 66.0 | 71.7 | 71.7 | 65.3 | 62.9 |
| Meadow bluegrass | 72.0 | 71.0 | 68.5 | 62.8 | — | 68.4 | 66.1 | 66.0 | 51.3 | 66.9 |
| Perennial ryegrass | 77.5 | 76.8 | 74.8 | 69.7 | 76.2 | — | — | — | — | — |
Table 2. Water content of lawn grass leaves in seasonal dynamics
(agricultural enterprise “Peremoga”, 2024-2025)
| Types | Growing season | 2024 (May) | 2024 (June) | 2024 (July) | 2025 (May) | 2025 (June) | 2025 (July) |
|---|---|---|---|---|---|---|---|
| Meadow fescue | I | — | 60.0 | 57.6 | 74.5 | 67.7 | 72.0 |
| II | 84.5 | 58.2 | 49.5 | 61.8 | 50.0 | 66.9 | |
| III | — | — | — | 62.6 | 50.1 | 69.3 | |
| Red fescue | I | — | 57.3 | 67.1 | 72.5 | 70.0 | 73.0 |
| II | 78.0 | 61.7 | 65.2 | 66.4 | 50.0 | 73.7 | |
| III | — | — | — | 51.2 | 53.1 | 78.0 | |
| Crested wheatgrass | I | — | 64.7 | 65.0 | 78.3 | 60.0 | 71.9 |
| II | 61.8 | 61.5 | 50.8 | 60.6 | 55.5 | 72.5 | |
| III | — | — | — | 59.0 | 52.7 | 71.1 | |
| Awnless brome | I | — | 64.2 | 64.0 | 67.2 | 68.9 | 69.3 |
| II | 77.5 | 67.6 | 56.2 | 66.5 | 59.9 | 70.0 | |
| III | — | — | — | 61.8 | 42.1 | 76.3 |
With the onset of dry periods, most lawn grasses experience a greater or lesser reduction in leaf water content and, as a rule, increase it again with a decrease in hydrothermal stress, which coincides with the secondary resumption of vegetation in the fall. However, in 2023 and 2025, due to a sharp decline in stress in July (with precipitation during the month amounting to 87 and 63 mm, respectively), the reduction in leaf water content ceased, and in some cases, it increased.
The absolute water content of leaves in plants of the first year of vegetation is higher than in plants of the second and third years (Tables 2, 4).
Water loss and the use of anti-stress agents
A decrease in leaf water content in lawn grasses with increasing drought has some positive effects. It increases the tissue's suction force and reduces transpiration rates, which can be considered a means of preventing further wilting and drying of plants. As modern research shows, the use of the anti-stress growth regulator Amino Energy Agro.Bio (optimal rate: 2 l/ha) during this period allows plants to more effectively manage cellular respiration, mitigating the effects of severe air drought and maintaining hormonal balance.
The absolute water content is directly related to the water-holding capacity of leaves, which is determined by the colloidal-chemical properties of the protoplasm and the content of water-holding colloids and osmotically active substances. This capacity is directly dependent on the ecology of the plant's growing environment and the severity of meteorological factors during the growing season. Modern researchers point to the possibility of using water yield as an integral indicator of plant hydrophilicity and the water-holding capacity of the leaf plasma of a given species, which is essential for plant resilience in adverse environmental conditions.
A general trend in water yield has emerged in various ecological groups: as drought increases, plants reduce water yield to a greater or lesser extent.
The rate of water loss by isolated leaves, as well as absolute water content, changes with age (Tables 3, 4). Leaves of red fescue, dog bentgrass, orchardgrass, and sickle-leaved alfalfa plants in the first year of vegetation lost water more rapidly than plants in the second and third years (observations were conducted at the same time).
Table 3. Water yield from isolated leaves of perennial cereals of different ages
(June, agricultural enterprise “Peremoga”)
| Types | Growing season | Water loss in % after 1 hour | Water loss in % after 2 hours | Water loss in % after 4 hours | Water loss in % after 6 hours | Water loss in % after 8 hours |
|---|---|---|---|---|---|---|
| Meadow fescue (2024) | I | 22.8 | 34.3 | 45.6 | 54.0 | 55.7 |
| II | 21.8 | 35.4 | 42.4 | 47.8 | 49.0 | |
| III | — | — | — | — | — | |
| Meadow fescue (2025) | I | 12.5 | 37.5 | 39.6 | 48.0 | 66.4 |
| II | 25.0 | 37.5 | 37.5 | 37.5 | 50.0 | |
| III | 19.4 | 22.2 | 27.7 | 33.3 | 38.8 | |
| Red fescue (2024) | I | 9.1 | 16.1 | 19.5 | 33.7 | 49.3 |
| II | 16.1 | 22.5 | 35.8 | 47.6 | 59.3 | |
| III | — | — | — | — | — | |
| Red fescue (2025) | I | 12.5 | 50.2 | 59.3 | 68.4 | 69.7 |
| II | 16.6 | 33.3 | 33.3 | 33.3 | 50.0 | |
| III | 25.0 | 37.5 | 37.5 | 40.6 | 53.1 | |
| Crested wheatgrass (2024) | I | 10.9 | 15.4 | 19.9 | 24.6 | 51.8 |
| II | 13.6 | 22.1 | 29.1 | 48.5 | 59.0 | |
| III | — | — | — | — | — | |
| Crested wheatgrass (2025) | I | 20.8 | 35.4 | 41.6 | 48.9 | 60.0 |
| II | 12.6 | 30.9 | 34.4 | 49.9 | 49.9 | |
| III | 14.3 | 29.1 | 33.3 | 33.3 | 50.7 | |
| Awnless Bonfire (2024) | I | 20.6 | 28.6 | 38.0 | 44.8 | 58.8 |
| II | 14.9 | 28.7 | 37.3 | 40.4 | 56.3 | |
| III | — | — | — | — | — | |
| Awnless Bonfire (2025) | I | 29.3 | 48.9 | 58.7 | 60.7 | 68.9 |
| II | 14.9 | 33.9 | 41.4 | 42.9 | 59.9 | |
| III | 20.0 | 33.3 | 40.0 | 42.0 | 42.1 |
Table 4. Daily water yield from isolated leaves and total water content of lawn grasses of different ages
(June 2021, Dnipro, Botanical Garden)
| Types | Growing season | Water loss after 1 hour, % | Water loss after 2 hours, % | Water loss after 4 hours, % | Water loss after 6 hours, % | Water loss after 8 hours, % | Water loss after 24 hours, % | Total water content, % |
|---|---|---|---|---|---|---|---|---|
| Meadow fescue | I | 7.6 | 16.9 | 23.6 | 33.9 | 40.3 | 63.5 | 69.4 |
| III | 3.9 | 10.7 | 14.8 | 23.5 | 29.1 | 53.3 | 60.1 | |
| Dog's bentgrass | I | 24.4 | 38.3 | 46.0 | 56.1 | 68.6 | 71.1 | 75.0 |
| III | 14.9 | 19.9 | 29.4 | 37.9 | 41.9 | 47.6 | 87.1 | |
| Cocksfoot | I | 10.2 | 14.6 | 23.1 | 35.1 | 45.7 | 65.7 | 74.1 |
| III | 7.1 | 8.0 | 11.3 | 17.1 | 22.6 | 60.8 | 73.9 | |
| Sickle-leaved alfalfa | I | 8.9 | 11.6 | 15.6 | 20.8 | 26.0 | 49.0 | 76.4 |
| III | 5.2 | 10.2 | 14.8 | 19.9 | 25.1 | 46.3 | 67.3 |
Water deficiency in lawn grass leaves
This tendency is manifested to a greater extent in red fescue, crested wheatgrass and dog bentgrass, and to a lesser extent in orchardgrass and sickle-leaved alfalfa.
Hydrothermal conditions during drought cause water deficit in the assimilation apparatus of lawn grasses. The magnitude of water deficit in plants depends on the bioecology of the species, the climatic conditions of the area, the maintenance regime, and a number of other factors.
Tables 5 and 6 present data on water deficit determinations in lawn grass leaves during the dry months of July–August 2022 and June 2025. A significant increase in moisture deficit from June to August was observed for all lawn grasses, regardless of the bioecological specificity of the species, and amounted to 9.6–28.47 on chernozem and 6.8–35.0 on leonardite substrate. An increase in deficit from June to July was observed for dog bentgrass, fine fescue, fescue, narrow-leaved bluegrass, red fescue, meadow fescue, crested wheatgrass, and awnless brome. The increase in moisture deficit in native xerophytes is most likely associated with the specificity of their development rhythm.
Table 5. Water deficit of leaves of leading lawn grasses in seasonal dynamics
(Dnipro Botanical Garden, 2022)
| Types | Water deficit (June), % | Water deficit (July), % | Water deficit (August), % |
|---|---|---|---|
| White bentgrass | 12.13 | 14.06 | 8:30 PM |
| Dog's bentgrass | 19.50 | 20.42 | 25.90 |
| Creeping bentgrass | 13.13 | 14.06 | 8:30 PM |
| Crested wheatgrass | 10.23 | 14.98 | 19.60 |
| Fescue | 10.93 | 21.41 | 23:30 |
| Meadow fescue | 13.35 | 13.79 | 20.15 |
| Red fescue | 13.60 | 18.17 | 22.50 |
| Furrowed fescue (fescue) | 13.84 | 26.20 | 28.47 |
| Cocksfoot | 18.85 | 20.20 | 26.20 |
| Meadow bluegrass | 14.50 | 19.54 | 28.19 |
| Poa angustifolia | 14.50 | 25.29 | 26.10 |
| Perennial ryegrass | 9.70 | 19:45 | 28.19 |
| Horned lotus | 16.38 | 20.59 | 22.07 |
| White clover | 19.36 | 21.15 | 24.25 |
Table 6. Water deficit of leaves of perennial cereal grasses in seasonal dynamics
(farming enterprise "Peremoga", 2025)
| Types | Growing season | Water deficit, % (June) | Water deficit, % (July) | Water content, % (June) | Water content, % (July) |
|---|---|---|---|---|---|
| Meadow fescue | I | 14.2 | 20.0 | 63.0 | 72.0 |
| II | 12.0 | 30.9 | 51.4 | 66.9 | |
| III | 7.9 | 28.3 | 42.2 | 66.6 | |
| Red fescue | I | 13.0 | 20.8 | 63.3 | 73.0 |
| III | 7.9 | 14.2 | 51.3 | 75.0 | |
| Crested wheatgrass | I | 6.8 | 20.0 | 60.4 | 71.4 |
| II | 9.0 | 32.7 | 53.7 | 72.5 | |
| III | 16.6 | 30.3 | 46.0 | 70.0 | |
| Awnless brome | I | 12.7 | 35.0 | 66.2 | 71.4 |
| II | 20.0 | 29.5 | 62.0 | 71.0 | |
| III | 25.0 | 34.9 | 51.0 | 76.3 |
Plants have completed their reproductive cycle and the body has begun preparing for summer depression.
Grass groups according to drought resistance
Visual observations of turf-forming grasses directly in cultivated phytocenoses of various ecological regimes, as well as in natural meadow cenoses during 2022-2025, make it possible to judge the degree of their field drought resistance.
Along with representatives of xeromorphic native flora (fescue, narrow-leaved bluegrass, crested wheatgrass, awnless brome), we consider mesophytes of varying degrees of xerophytization (fine-leaved fescue, rough-leaved fescue, and red fescue) introduced from the temperate forest zone to be significantly drought-tolerant grasses. Under natural moisture conditions, these plants ceased growing in July and August; summer depression gave way to vigorous renewal of vegetation in the fall with a decline in hydrothermal stress. Under moderate watering conditions, vegetation continued throughout the summer. Leaf turgor was easily restored with moisture. These plants are fairly tolerant of soil drought but are less tolerant of airborne drought.
Moderately drought-tolerant grasses are predominantly mesomorphic. Mesophytic plants are more demanding of soil moisture and relatively resistant to aerial drought. Plants in this group require regular watering during the summer (bent grass, creeping bent grass, meadow fescue, perennial ryegrass, etc.).
Plants with low drought tolerance include mesophytes, which do not tolerate air and soil drought well. These turf grasses require abundant watering (white bentgrass, dog grass, bluegrass, white clover).
When comparing data on shoot formation and biomass of wild grasses grown on ordinary chernozem and on leonardite soil under similar conditions, an intensification of these processes was noted for a number of species in the latter case. The use of the organic stimulant Totem Agro.Bio (at an optimal rate of 2 l/ha) during the preparation of the leonardite substrate significantly activated the microflora and extended the growing season. Specifically, by the end of the first year of vegetation, the red fescue grass stand density in the leonardite soil was 141 shoots/dm2 , while on chernozem it was 124 shoots/dm2 . By the end of the second year of vegetation, 225 shoots/ dm2 were formed on leonardite , while on chernozem only 176.
Similar results were obtained for the biomass of sod-forming grasses, with the leonardite substrate primarily stimulating the development of vigorous turf. Red fescue grown on leonardite had a root mass of 1.33 kg/m2 by the end of the first growing season , compared to 0.63 kg/m2 on chernozem ; by the end of the second growing season, the respective values were 2.35 and 1.47 kg/m2 . Similar data were obtained for a number of other perennial sod-forming grasses.
Conclusions
- The degree of water saturation, water yield and water deficit of lawn grass leaves depend mainly on their bioecology and are associated with the hydrothermal environment and environmental conditions of the habitat of a given crop phytocenosis.
- The combination of laboratory determinations of the water regime with field observations of drought resistance of lawn grasses made it possible to identify groups of significantly drought-resistant (fescue, narrow-leaved bluegrass, red fescue, awnless brome grass, crested wheatgrass), moderately drought-resistant (meadow fescue, perennial ryegrass) and slightly drought-resistant (white and dog's bent grass, pine bluegrass) plants that can be recommended for turf coverings of various purposes and ecological regimes in the steppe zone.
- The most dense grass-turf cover, resistant to unfavorable meteorological factors of the steppe zone, is formed by red fescue and crested wheatgrass on a leonardite substrate.
Based on this fundamental scientific data, Agro.Bio offers modern, comprehensive solutions for the development of resilient lawns and the phytoremediation of challenging areas. The use of Ukrainian leonardite in synergy with Agro.Bio's innovative Amino Energy and Totem (2 l/ha) products reliably mitigate climate stress and water shortages. The development of these biotechnologies enables Ukrainian farmers to create high-quality, durable turf, even in the harsh conditions of the steppe drought.