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В статье представлена методика определения степени водообеспеченности растениеводства в заданных почвенных, растительных в водных условиях, а также расчет дефицита осадков любой вероятности. В методике использовали многолетние метеорологические материалы и эмпирические коэффициенты для расчетов испарения, предложенные Остроменцким. В работе представлены результаты исследований для метеостанции Бялысток (рис. 1,2,3), а также другие примеры использования.
Application of irrigations to the farmland depends to a large extend on the course of plant transpiration in relation to soil humidity and evaporation conditions of the atmosphere. The values of the water stress index (ISW) in relation to the level of transpiration (ETm) have been determined in the conducted here physical-physiological investigations. It allows for the evaluation of the level of soil useful retention in its dynamic aspect, and for the more accurate computer simulation of transport processes in the unsaturated soil media.
This paper describes the method of determination of soil hydraulic conductivity using a new measuring system SP-86. The system cooperates with the IBM PC-86 XT/AT computer in an analog- digital disposition. The results obtained from testing of particular elements of the system and the programme have pointed out that the method for determination of conductivity K(h) can be widely applied in designing and exploitation of drainage systems.
W pracy przedstawiono wyniki badań zużycia wody przez rośliny w warunkach rekultywowanych składowisk odpadów komunalnych. Badania prowadzono w lizymetrach stosując metodę bilansową oraz w warunkach polowych stosując bezpośredni system pomiaru transpiracji. Uzyskane wyniki obejmują cały sezon wegetacji i mogą być zastosowane do sterowania nawodnieniami metodą bilansową.
The maximum time between, irrigations (T max) was estimated for the two high-yielding grass-lands in field experiments. The intensity of water utilization process was conditioned by the amount of water stored in the beginning of the studied period, and by the 24-hour insufficient air-humidity levels in the studied period. The period of time during which the amount of available water stored was used up was not constant and ranged from 17 days in April to 7 days in July in case of loamy soil (the experimental stand no. 1), and from 15 to 7 days in case of sandy soil.
В работе представлена методика определения необходимости орошения в данном районе страны на основании анализа атмосферных и почвенных засух, а также определения допустимого промежутка времени между атмосферными осадками или отдельными поливами (Тmax). Методика позволяет также определять для данного периода Тmax величины снижения урожая и возможности экономического анализа для оценки районирования орошения сельскохозяйственных культур.
This study concerns the determination of soil moisture content at field capacity (PPW) and at the point limiting biomass production (PHWR) as well as the relationships between water stress index (ISW) and evaporative demand of the atmosphere. The results obtained have shown that calculation of irrigation norms deciding upon the hydraulic parameters of irrigation networks should include a dynamic character of available soil water both at the designing stage and at the conditions of exploitation. Some problems of microirrigation, in which the role of soil water retention in water management is very important, are also discussed. Water retention might be especially important when using microsprinklers, while during drip irrigation such retention might even be harmful.
A number of factors are known to influence the hydraulic conductivity (K) of soils. While a large number of laboratory and field methods have been developed over the years, most of them are applicable mainly for the measurement of hydraulic properties in saturated soils. Moreover, those methods omit such factors affecting hydraulic conductivity as soil volume changes (swelling or shrinkage) and external load simulating the location of the soil tested. The purpose of this paper is to present direct and simple methods for estimation of hydraulic properties, mainly conductivity of unsaturated soils. The methods proposed are based on evaluation of soil-water potential and water outflow from a soil sample. The test methods allow the 1- and 3-dimensional stress states of the soil and pore-fluid to be monitored. The procedure allows also to monitor the changing soil moisture using the TDR technique. The modified apparatus (triaxial apparatus, consolidometer and tempe pressure cell), soils and procedures are described first, and then the results of tests are presented and reviewed. Interpretation of test results is made using the Multi-step method. Results obtained showed that the stress states simulating the location of soil affected the hydraulic parameters significantly. The test results confirmed the usefulness of the methods proposed for testing the porous medium with the geometrical changes of soil (swelling/shrinkage) considered.
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