Energy value of biomass produced on various land uses in a sandy loam Haplic Luvisol Energijos sukaupimas biomasėje taikant įvairias žemėnaudas priesmėlio paprastajame išplautžemyje (Haplic Luvisol)

The article discusses the changes in energy accumulation in the biomass during a 21-year arable land renaturalisation process. The relevance of renaturalisation studies in South-Eastern Lithuania is determined by the low-productivity of the soil covers in this area and low energy production obtained from traditional agricultural crops grown on lowproductivity agricultural soils. The aim of this study is to evaluate various methods of sandy loam Haplic Luvisol renaturalisation by comparing the total energy accumulated on pine afforested land use, unmanaged and managed grasslands against the productivity of the traditional agricultural systems. The accumulation of the total energy under various land uses was governed by the plants and their cultivation period. Downward trend of productivity during the period of 1995–2015: forest plants (195%) → fertilized managed grassland (162%) → fertilized cropland (100%) → unfertilized managed grassland (95%) → unfertilized cropland (61%) → unmanaged grassland (50%). When comparing the plant biomass production during the entire study period, it was established that mineral NPK fertilization significantly (by 1.63 times) increased the energy productivity of the cropland. It is expedient to preserve and expand the managed grasslands typical of the traditional Lithuanian landscape and crucial for the conservation of biodiversity. Furthermore, the productivity of unfertilized managed grassland is adequate to the productivity of the fertilized cropland, or exceeds it by 67% if NPK fertilizers are applied. Mineral NPK fertilization significantly (by 1.71 times) increased the accumulated total energy of the managed grassland. The accumulation of energy changes significantly in the fallowing fields. Natural vegetation plants of non-cultivated sandy loam are not productive; they produce only half the amount of the total energy compared with the cropland plants or fertilized managed grasslands.