The creation of artificial meadows and pastures by sowing suitable grasses or grass mixtures is resorted to when the main objective is to improve low-productive natural meadows and pastures, to create grass fields in forage and specialised field rotations, to grass wasteland and to reclaim areas used for industrial purposes.
Artificial meadows and pastures exceed low-productive natural meadows and pastures by a factor of 3 to 10 in terms of yields of green mass, feed units and digestible protein. At the same time, they are distinguished from other forages by the significantly lower cost of the resulting production.
Choice of types. The selection of grass species is crucial for the success of the grassing. Suitable mixtures of perennial leguminous and cereal grasses are most often used, and in some cases pure crops are preferred - in cases of excessive wetting, severe drought, etc. Perennial grass mixtures in most cases give higher yields, better tolerate adverse climatic conditions, resist weed infestation better, are less attacked by diseases and pests.
According to the duration of use, grass mixtures are short-lived, with a duration of use of 2-3 years, medium-long-lived - 4-6 years and long-lived, which are used for 8- 10 years and more. However, long-lived grasses are maintained by overseeding.
According to the number of species of which they are composed, they are simple, simple and complex. The simple ones consist of 2-3 components, the simplified ones of 4-6 and the complex ones of more than 7.
According to the use, grass mixtures are hay, pasture and combined use. When determining the composition of grasses, certain conditions must be taken into account, such as the longevity of the mixture, the purpose for which it was created, the method of use, the ecological characteristics of the area (soil type, soil pH, altitude, rainfall, temperature), the biological and ecological characteristics of the individual species and the relationships between them when grown in a mixed crop.
The short duration mixtures include tall, fast growing, relatively short duration species which have a positive effect on soil fertility and ensure high hay yields. These mixtures are dominated by leguminous grasses, which account for 80 % and cereals for 20 %.
In medium duration mixtures legumes contribute 30-50 % and cereals 50-70 %. Of the cereals, suitable species are ryegrass, tall ryegrass, timothy, meadow fescue, and of the legumes, alfalfa, sainfoin, common bird's-foot trefoil.
Cereal species predominate in long-lived mixtures. Medium-duration, fast-growing and long-duration, slower-growing species are included to ensure uniformly high yields throughout the period of use. Suitable species include festuca rubra, common meadow-grass, bromus inermis, dactylis glomerata and timothy. Legumes contribute 10-20 %. Suitable species are white clover, common bird's-foot trefoil, sainfoin. The sowing rate of the finished mixtures is specified by their manufacturer.
FEATURES IN AGROTECHNICS
Perennial grasses require well tilled, settled, nutrient-rich and weed-free soil. When artificial grass stands are established on arable land, the tillage is as for alfalfa.
The timing and method of sowing have a strong influence on the development of perennial grass mixtures and are therefore determined by the biological characteristics of the species, the specific climatic conditions and irrigation possibilities. Under irrigated conditions, grass mixtures are preferably sown in the summer-autumn period, but no later than mid-September, in order to germinate and root well before the onset of winter.
Grass mixtures can also be sown early in spring to use the moisture from winter and spring rainfall for good germination, good rooting and grass development until drought occurs.
Pre- and post-emergence rolling are mandatory measures to facilitate moisture flow to the seed and promote friendly germination.
Grass mixtures can be sown alone or under a cover of annual crops . Cover cropping is suitable for wetter areas, with relatively even rainfall distribution during the growing season, with which conditions cover cropping does not suppress grasses as much as under moisture deficient conditions.
The sowing of grass mixtures is carried out at a spacing of 10-12 cm. If the mixture includes seeds of different sizes and is not factory-mixed, they are sown in groups according to their size, usually in a perpendicular direction.
The small seeds (bird's-foot trefoil, timothy, common meadow-grass) are sown at 0.5-1 cm, the medium-sized ones (alfalfa, red clover, meadow fescue, dactylis glomerata, perennial ryegrass) at 1.5-2 cm, and the large ones (sainfoin, bromus, tall ryegrass) at 2-4 cm.
Manufacturers of ready-mixtures give an indication of the sowing depth. We recommend sowing at about 2 cm depth, no more.
Fertilisation should be tailored to the species composition, growing conditions and use of the mixture. Phosphorus and potassium fertilisers are applied with the main tillage, storing for the whole period of use in
an amount of 6-8 kg active substance per hectare.
Under non-irrigated conditions, nitrogen fertiliser is applied early in the spring and under irrigated conditions, the prescribed amount of nitrogen fertiliser is applied several times, in the spring and after each use, to ensure a more even
distribution of the yield among sub-growths. Where cereal grasses predominate in the grass mixture, the nitrogen rate is higher at 10-14 kg/dcaa. Where the legume component is high, 6-8 kg of nitrogen per dcaa is adequate.
Care during the growing season is mainly limited to weed control using herbicides which do not destroy the more sensitive leguminous grasses. Basagran is used at 300 ml/dcaa when legumes have formed 2-4 true leaves.
USE OF MEADOWS AND PASTURE
Meadow use: The yield and quality of hay from natural and artificial meadows, the duration of use and their variability depend largely on the timing of mowing. The timing of cutting of natural meadows is determined specifically for each type, taking into account the development phase of the main species.
For cereals, the most appropriate time is the beginning of heading, for legumes the beginning of flowering. Depending on the degree of weed infestation, the characteristics of the individual species (degree of roughening, characteristics of the various species) and weather conditions, mowing may be hastened or delayed. Both late and early mowing of meadows can cause deformation of the meadow vegetation and one-sided development of the plant community. In order to avoid this, some authors recommend the introduction of the so-called 'grassland' hay rotation.
In the case of artificial meadows, due to their simpler composition, mowing is carried out according to the characteristics of the species included in the grass mixture.
The grass from the meadows is used to make hay, and in some wetter years for haylage. Artificial meadows dominated by leguminous grasses can also be used to make hay flour. The technology for making hay, haylage and silage is the same as for pure legume crops (alfalfa, clover, etc.).
Use of pastures: the way and intensity of use of both natural and artificial pastures is important for their productivity and longevity. Under (free) rough grazing, soil compaction leads to changes in the physical properties of the soil, which affect grass development. Species that require better aeration quickly drop out of the grassland and are replaced by more resistant grasses that are less productive and of lower quality. Under free grazing, only 40% of the grass vegetation is used.
In artificial pastures, the sward is established over several years, and therefore suffers more from soil compaction. As a result of the widespread application of free grazing, the available grasslands in the country are low-productive, with a severely deteriorated species composition. The maintenance of natural and artificial grasslands requires regulated use through plot grazing and its new modifications, such as portion grazing, frontal grazing, strip grazing, etc. In plot grazing, areas are divided into plots which are used in sequence. In determining the number of plots, account is taken of the time required for grass to grow and the days of grazing in each plot. Under favourable conditions, grass recovers more quickly, while under unfavourable conditions it recovers more slowly. This requires 1-2 reserve plots.
The following principles should be observed in the systemic grazing:
1. The number and type of animals should be adapted to the productive possibilities and characteristics of the pasture.
2. The grazing of each plot should start when the grass reaches 'pasture maturity', i.e. at the end of tillering and at the beginning of spindling.
3. Livestock to remain in each plot for up to 6 days and grazing to cease when approximately 75% of the grass has been used.
4. After each use, provide the necessary rest period during which time appropriate grassland care should be applied.
With the aid of electro-pastures it is possible to use the most perfect variants of plot grazing, such as ration, frontal and strip grazing.
The principle of ration grazing consists in measuring out an area of pasture whose grass cover will be able to satisfy the daily or half-day ration of green matter of the animals. The use of this type of grazing is highly efficient only in the presence of grass stands with good species composition and high productivity.
The material is based on Bulgarian and foreign publications.
January, 2016.
Еng. Evelina Marinova