Потенціал біопродуктивності осушуваних земель України

The purpose of the work is based on the generalization of the results of long-term researches of scientific institutions of the NAAN in the Livoberezhnyy, Pravoberezhnyy, Western Polissya, as well as on intrazonal soils of river floodplains to substantiate the need to restore the effective use of melioration arable land and natural forage lands of the humid zone on the basis of evaluation of their potential bioproductivity for optimization of water -air, nutrient regimes, crop rotation and other factors.   In the conditions of the floodplain of the rivers in the vegetation specialization of agrarian production, the maximum productivity of the crop rotation: 1, 2 - corn for grain, 3 - soybeans, buckwheat on the background of the mineral fertilizer system will reach the level of 9 t f.unit / ha. For livestock specialization in crop rotation, which provides close to optimal ration of feeding of milk cattle: 1, 2 - corn for grain, 3 - soybeans, 4 - corn for silage, perennial grasses, sylvia permeated leaves, productivity of arable land under optimal conditions of moisture and nutrition will be 10 tons of f. units per hectare. According to the bioenergy specialization of production activity, it may be most expedient to grow Salix triandra L. with a difference in terms of planting in 1 year - 40 t / ha of dry matter. Regarding the conditions of the Left Bank Polissya for well-cultivated sod-  podzolic soils in the conditions of humidity and nutrition, which are close to optimal ones, it is possible to recommend 4-field crop rotation: 1 - winter and spring crops, 2 - clover, lupine, 3 -  milk-waxy corn or grain and 4 - potatoes with an expected productivity of 12 t f.unit / ha. Such crop rotation, which involves the production of coarse and juicy fodder, is suitable for introduction in the presence of a developed livestock industry. In the absence of livestock breeding with a purely planting crop specialization, it is possible to recommend a 3-fiel crop rotation with the production of only commercial crop production: 1 - winter and spring crops, 2 - potatoes, 3 - maize for grain and productivity level of 12 t f. unit / hа.         In the Right-bank Polissya, the highest yield was observed at the cultivation of a mixture of grass (Phléum praténse L. + Bromus inermis + Agropyrum glaucum R.) - 9 t / ha of dry matter. In the meliorationed arable lands of the region, the expected level of productivity of crop rotation: 1 - cereals 2 - milk-waxy corn, 3 - lupine, 4 - clover will be at level of 11 t / ha of dry matter. The bioenergy trend of agrarian production is the productivity of crop rotation: 1 - maize for silage, 2 - clover can reach 13 t / ha of dry matter.    In Western Polissya, the grass-mixed Galega oritalis L.50% + Bromus inermis 50% provide at a level of 10 t f. unit / ha. On organic soils - feed  crop rotation: 1 - Rhaponticum Transbaikal, 2 - Galega oritalis L., 3 - Raphanus sativum d., 4 – Echinochloa flumentacea will be able to receive 17 t f.unit / ha, on sod-podzolic soils of crop rotation: 1 - Rhaponticum Transbaikal, 2 - Lotus corniculatus, 3 - Raphanus sativum d., 4 - Echinochloa flumentacea will be able to receive at the level of 12 t f. unit / ha. From one-year grassy energy crops, sugar sorghum produces - 22 t / ha of dry matter, from perennial herbaceous Miscánthus  - 24 t / ha of dry matter, Salix triandra L. provides 55 t / ha for the 3rd year, Salix viminalis L. of domestic selection -   52 t / ha, Swedish selection - 84 t / ha of dry matter.У статті узагальнено результати багаторічних досліджень, спрямованих на розробку технологій підвищення біопродуктивності осушуваних територій річкових заплав, лівобережного, правобережного та західного Полісся на органогенних і мінеральних ґрунтах, на орних землях і кормових угіддях. Встановлено, що за оптимізації водно-повітряного, поживного режиму ґрунту та складу культур у сівозмінах очікувана продуктивність орних земель становить 10-12 т к. од./га. У сприятливих умовах вирощування традиційні багаторічні трави і травосумішки забезпечують до 15 т к. од./га. На органогенних ґрунтах перевагу мають малопоширені нетрадиційні кормові і трав’янисті енергетичні культури з максимальною продуктивністю відповідно 27 та 29 т/га сухої речовини. З дерев’янистих енергетичних культур максимальний вихід сухої речовини дає верба прутовидна шведської селекції – 84 т/га сухої речовини. Проведені дослідження свідчать про доцільність відновлення ефективного використання осушуваних земель Україн

Band structure of CuMnAs probed by optical and photoemission spectroscopy

The tetragonal phase of CuMnAs progressively appears as one of the key materials for antiferromagnetic spintronics due to efficient current-induced spin-torques whose existence can be directly inferred from crystal symmetry. Theoretical understanding of spintronic phenomena in this material, however, relies on the detailed knowledge of electronic structure (band structure and corresponding wave functions) which has so far been tested only to a limited extent. We show that AC permittivity (obtained from ellipsometry) and UV photoelectron spectra agree with density functional calculations. Together with the x-ray diffraction and precession electron diffraction tomography, our analysis confirms recent theoretical claim [Phys. Rev. B 96, 094406 (2017)] that copper atoms occupy lattice positions in the basal plane of the tetragonal unit cell

Local structure of relaxor ferroelectric SrxBa1-xNb2O6 from a pair distribution function analysis

Pair distribution function analysis of neutron-scattering data and of ab initio molecular dynamics results have been employed to study short-range structural correlations and their temperature dependence in a heavily disordered dielectric material SrxBa1-xNb2O6 (x = 0.35, 0.5, and 0.61). Intrinsic disorder caused by a partial occupation of the cationic sites by differently sized Sr and Ba atoms and their vacancies introduces important local strains to the structure and directly influences the Nb-O-6 octahedra tilting. The resulting complex system of tilts is found to be both temperature and Sr-doping sensitive with the biggest tilt magnitudes reached at low temperatures and high strontium contents, where ferroelectric relaxor behavior appears. We find evidence for two Nb-O-6 subsystems with different variations of niobium-oxygen bond lengths, distinct dynamics, and disparate levels of deviation from macroscopic polarization direction. These findings establish a detailed picture of the local structure of SrxBa1-xNb2O6 and provide a deeper insight into the origins of the materials dielectric properties.This work was supported by the Czech Science Foundation (Project No. 16-09142S). The computational part of this research was undertaken on the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government.

Structural analysis of strained LaVO 3 thin films

International audienceWhile structure refinement is routinely achieved for simple bulk materials, the accurate structural determination still poses challenges for thin films due on the one hand to the small amount of material deposited on the thicker substrate and, on the other hand, to the intricate epitaxial relationships that substantially complicate standard x-ray diffraction analysis. Using both electron and x-ray diffraction, we analyze the crystal structure of epitaxial LaVO3 thin films grown on (1 0 0)-oriented SrTiO3. Transmission electron microscopy study reveals that the thin films are epitaxially grown on SrTiO3 and points to the presence of 90° oriented domains. The mapping of the reciprocal space obtained by high resolution x-ray diffraction permits refinement of the lattice parameters. We finally deduce that strain accommodation imposes a monoclinic structure onto the LaVO3 film. The reciprocal space maps are numerically processed and the extracted data computed to refine the atomic positions, which are compared to those obtained using precession electron diffraction tomography