Soil factors of floodplain soils that limit growth of energy crops
Authors: Kholodna A. S. 
Published: February 2020

Nowadays it is hard to find a country with a big number of lands, which are non-used in any sphere of production. Taking into account hard ecological situation on the planet, each year more and more countries join to zero waste production. The agricultural branch is not an exception. Searching and creation of renewable energy sources are the main subjects of study for scientists in many fields of science. Starting from the 70s in Sweden government implemented the production of renewable energy. That energy based on burning the products of plant origin. At this period on the planet oil crises was increasing. This fact motivated scientists and businessmen for searching chip and effective energy sources. One of such sources is the biomass of fast-growing plant species which can be successfully recycled into biofuel. Renewable energy production in Ukraine is only on the first phase of development. A major limiting factor is the issue of determining the eligibility criteria of soils on which one can place the plantation of energy crops. It is noted that there is a possibility of growing energy crops on hydromorphic soils of floodplains, which are not used in traditional farming and forestry. Determining of soil limiting factors that can affect the growth of energy crops was conducted in the floodplain of river Vilhovatka, Novo-Vodolazhskiy district, Kharkiv region in 2016. Researches of the development and growth of energy crops (energy willow and giant miscanthus) were held on the meadow alluvial hard loamy soil and on meadow-marsh alluvial hard loamy soil. These soils by their genesis belong to azonal ones. High developed accumulative processes, which serve for organic and both macro and microelements conglomeration, are the specialty of their soil formation. Specific acid-base regime is inherent for hydromorfic soils. It’s caused by their periodical or constant water logging. For both soils the parent rock is an oxbow alluvium. The level of ground water occurrence was installed by drilling in spring, summer and fall. Energy willow – is one of the willow species that is processed for solid fuel. The usage of hydromorphic soils for willow planting has good perspectives. These soils can’t be used in agriculture without drainage. Here lies a clear parallel and duality of energy willow – the nature of its cultivation is more similar to food crops, but in contrast, willow grows on typical forest soils. In addition it can be mentioned that willow plantations have been used as a factor of preventing erosion for a long time already. The plants develop strong root system that allows consolidating river banks, gullies and ravines. Giant miscanthus – is a perennial grass that in botanical features reminds cane. The benefits of growing this crop lie not only in its growing for energy needs. Giant miscanthus has the following characteristics: tolerance to almost all types of soils; resistance to salinity (which is important in terms of its possible growth on alluvial-meadow saline soils); ability to grow on heavy soils; the ability to produce large amounts of biomass, which is relatively easy to collect and process with the existing technology and, of course, it’s ability for significantly improving of the environmental situation in forest landscapes. The paper presents the results of studies of the establishment of factors that affect the growth of energy crops in flooded soils. It was found that the main limiting factors are: the level of occurrence of groundwater and the concentration of heavy metals. Depending on the type of floodplain soils the level of groundwater occurrence varies considerably. This factor generally determines the character of the growth of the studied crops. Once again it was confirmed that the floodplain soils contain high concentrations of iron, including ferrous (Fe2 +) and oxide (Fe3+) forms. It is shown that the form of ferrous iron in high quantities is a limiting factor for normal growth and development of energy plants. On the meadow alluvial soil of the central floodplain energy crops grew much better (especially energy willow) than in the meadow-marsh soil of the terrace floodplain. Giant Miscanthus showed better stability, compared to energy willow, to its growing conditions. Also the article deals with the issue of energy willow phytoremediation ability, through which it is possible to partially solve the problem of some soils’ contamination with heavy metals.