<p>The influence of long-term use of mineral and organic fertilizers, crop rotations, plant residues, soil treatment systems on humus content of common chernozems and stabilization of productivity of field crops in the arid conditions of the Middle Volga region is considered on the example of researches in the Samara area. The zone climate of field experiments is characterized as extremely continental. The sum of the active temperatures (above 10°C) is 2,800-3,000°C. The average annual rainfall is 454.1 mm with fluctuations over the years from 187.5 mm to 704.6 mm. At some years, precipitation does not happen within a month or more. Hydrothermal index in May-August is 0,7, the duration of the frost-free period is 149 days. If the humus content in the region is 4.35-4.52%, then, it is necessary to introduce 6.7-8.0 t/ha of manure per year to maintain the balance of the deficit. The introduction of biological methods for the conservation and reproduction of soil fertility (green fertilizers, perennial grasses, straw as fertilizer) reduces the loss of humus by 0.15-0.24 t/ha. This makes it possible to increase the payback of mineral fertilizers, which must be taken into account when developing fertility reproduction systems for soils. In the variants with minimal and differentiated cultivation of the soil during crop rotation in 30 years of the study, the loss of humus in the 0-30 cm layer decreased by 0.04 - 0.73% (43-789 kg per year with maximum values in the combination of direct seeding of spring crops with deep loosening for a number of crop rotations is 4.14%, significantly exceeding the control (by 0.54%). The decrease in soil fertility in the variants with constant plowing and minimal tillage contributed to an increase in the conjugation of productivity of crops with humus. Based on the research, in order to preserve the fertility of the soil of ordinary chernozem, it is necessary to use green fertilizer, leguminous perennial grasses. In the regional rotations of crop production, new generation technologies are recommended, the basis of which is differentiated tillage with the use of crushed straw as fertilizer.</p>
The results of studies on the study of six variants of sunflower cultivated by production system ExpressSun (predecessor barley), on ordinary Chernozem during 2013-2018 are presented. Research on hybrid P63LE10 showed the promise of deep loosening of the soil as the main soil tillage. It ensures, the yield of 2.2-2.5 t/ha of oilseeds after the application of fertilizers. It is established that one of the main quality indicators of oilseeds – oil content – depends on the mass of 1000 seeds, while the highest value detected on the maximum level of intensity of 51.3-51.5 g, that is 1.6-2.6 g (3,2-5,3 %) more than the rest of the studied variants. The maximum oil content is on natural fertility background – 47.8-49.2 %, which was 1.3 and 1.9 % more than in the fertilized variants. In the study of the nature of oilseeds they are revealed trends of dependence on the used means of intensification similar to the oil content of seed at a positive relationship with the crop yield (r= 0.71-0.92*). Application of mineral fertilizers in a dose NPK30 provides stabilization of productivity and quality of oil seeds in any climatic conditions year. On the basis of the obtained data they are revealed manufacturing operations that provide high productivity and quality of seeds: the fertilizer dose NPK30, deep loosening to 25-27 cm (PCH-4.5), spring harrowing (BZSS-1.0), pre-sowing cultivation (OPO-4.25), consolidation of the soil (3kksh-6), sowing (SSTV-6), the harrowing on shoots in one track (BZSS-1.0), treatment with herbicide (Express, 50g/ha).
The results of the study of five seeding rates (variants) in the cultivation of spring durum wheat Bezenchukskaya Niva with seed treatment with Scenic Combi preparation (1.4 l/t) in order to identify the optimal rate are presented. On ordinary chernozem for 2017-2020 in the arid conditions of the Volga region, it was found out that when growing a crop for winter wheat, a decrease in seeding rates contributed to an increase in the coefficient of total and productive bushiness, the weight of grain from the ear and plant, the number of grains from the ear. On average, over the years of research, the yield of spring wheat grain at seeding rates of 2.0-5.0 million/ha was 2.00-2.22 t / ha. Under favorable weather conditions, the yield advantage was the norm of 4.0-5.0 million/ha by 6.2-37 %, in the acutely arid 2.0-3.0 million / ha by 3.4-16.4 % more, compared to other options. Wheat yield was most affected by the air temperature during the growing season (r=-0.97* to -0.99*). Of the elements of the structure, the maximum conjugacy with the yield at the norms of 1.0-4.0 is noted with the number and weight of grain from the ear and plant, the height of the plants (r=0,97*-1,0**). On average, over the years of research, the highest net income was established on the variants with the norm of 3.0-4.0 million / ha-17100.4-17442.8 rubles / ha, which is 761.9-1704.7 rubles/ha (4.7-10.8 %) more than the variants with the norm of 2.0 and 5.0 million/ha. The maximum level of profitability was revealed at the rate of 1.0 million / ha-194.6 %, which is 9.6-41.3% more than the options with the rate of 2.0-4.0 million / ha. Based on the conducted research, the seeding rate of 2.0-4.0 million/ha is recommended for the cultivation of spring durum wheat for commercial purposes. In the original seed production – 1.0 and 2.0 million/ha, providing a multiplication factor of up to 57.8 kg/kg of grain.
In our work, the governing system of equations consists of a mass conservation equation, a momentum equation and an equation for the drug concentration in the brain tumor. This system describes the penetration of drugs into the brain tumor (there is a cavity after surgical removal of a cancer tumor), which fill up the cavity after a surgery. We use techniques of computational fluid dynamics (CFD) to get a solution of the derived partial differential equations (Navier-Stokes equation with additional scalar equations and force terms) and obtain a saddle point problem after discretization of the governing system of equations with finite elements such that we can use modern CFD tools and software like FEATFLOW to get numerical solutions of this problem.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.