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1

Dynamic process and model simulation of soil water content during citrus growth period

Zhu Shijiang, Li Hu, Xu Wen, Zhang Tao, Liu Caihong, Peng Yuqiang

Acta Geophysica

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2023

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Vol. 71, no. 3

1525--1537

EN

The change of soil water content in crop root system is the basis for the designing of water-saving irrigation scheduling. In order to explore the dynamic changes of soil water content, our study carried out long-term monitoring on the soil content at different depths in a typical citrus orchard. In this concern, water contents, salinities, and nitrate concentrations were measured weakly and were compared with the model predictions. One of the important perspectives is the growth restricting factor in the soil water, yield, and fruit quality of citrus. Combined with the meteorological data, the changing characters of soil water content and its responses to evapotranspiration and precipitation during the whole growth period were investigated. And then the changing process of soil moisture was simulated through the soil water balance model. The results showed that during the whole growth period of the citrus, the soil water content buried at 40 cm depth had the best correlation with that in the main active layer of citrus root system (0–60 cm), between which the correlation coefficient reached 0.988. Therefore, the depth of 40 cm could be used as the representative depth of soil water content monitoring. Under the combined effects of precipitation and evapotranspiration, soil depth could influence the changing process of soil water content, of which the effect weakened with the increase in depth. The water balance model within 1-week timescale was appropriate to simulate the changing process of soil water content.

2

Spatial Scale Analysis of Soil Water Content in Agricultural Soils of the Nitra River Catchment (Slovakia)

Tárník Andrej, Igaz Dušan

Journal of Ecological Engineering

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2020

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Vol. 21, nr 1

112--119

EN

Determining the soil water content (SWC) in a soil profile is very important task for agriculture and also for a wider ecological context. The spatial and temporal variability of SWC is a elementary issue for agricultural practice, irrigation management, or landscape management globally. Various methods are used for obtaining the SWC data. Every method has some advantages and also disadvantages. Many of them are focused only on one dimension but modern precise agriculture needs the information about SWC in spatial scale. This study is focused on the spatial scale analysis of SWC in the Nitra river catchment for years 2013 and 2014. The HYDRUS 1D hydrological model and GIS tools were used for the creation maps of SWC. Combination of the measured and simulated data was used for the creation of the unique spatial maps of soil moisture in 0–30 and 30–60 cm soil horizons. Validation of our method shows trustworthy results. Soil water storage and fulfillment of maximum soil water storage were analysed with using the created maps.

3

Decomposition of Fine Woody Debris from Main Tree Species in Lowland Oak Forests

Ostrogović M. Z., Marjanović H., Balenović I., Sever K., Jazbec A.

Polish Journal of Ecology

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2015

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Vol. 63, nr 2

247--259

EN

Decomposition is an important carbon flux that must be accounted for in estimates of forest ecosystem carbon balance. Aim of this research is to provide estimate of fine woody debris decomposition rates for different tree species and sample sizes also taking into account the influence of specific microsite meteorological conditions on decomposition rates. In this paper we present results of the first two years of the experiment designed to last six years. Study was conducted in managed lowland oak forest in central Croatia. Decomposition rates (k) of fine woody debris (diameter 0.5–7 cm) for four species (Querus robur L., Carpinut betulus L., Alnus glutinosa Gaernt., Fraxinus angustifolia L.) in four size classes were estimated using litter bag method and mass loss equation of Olson (1963). Overall average k in our study was 0.182 ± 0.011 year-1. Results indicate that decomposition rate is affected by the size of the debris, with the smallest diameter branches (<1 cm) decomposing is significantly faster (k = 0.260 ± 0.018, P <0.05) than the larger one. Tree species from which debris had originated also affected decomposition, although to a lesser extent, with hornbeam samples having significantly (P <0.05) higher average decomposition rate (0.229 ± 0.028), compared to that of ash samples (0.141 ± 0.022). Proportion of variability in k explained by variables ‘species’ and ‘size class’ was assessed with general linear model (R2 = 0.644) also taking into account variables like soil temperature and soil water content. Sample size class explained 22.2%; species explained only 9.4%, while soil water content and temperature combined explained 32.8% of the variance of k. Rate constants obtained within this study might be useful in modelling ecosystem carbon balance for similar lowland forest ecosystems in Europe.

4

Ocena zmienności zasobów retencji glebowej w parku południowym we Wrocławiu

Orzepowski W., Kowalczyk T., Pokładek R., Pęczkowski G., Faron S.

Inżynieria Ekologiczna

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2015

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Nr 43

160--165

PL

W pracy przedstawiono charakterystykę stosunków wodnych i ocenę zmienności zasobów retencji glebowej na terenie Parku Południowego we Wrocławiu. Oceny tej dokonano na podstawie pomiarów uwilgotnienia gleby wykonanych w roku 2012 i 2013 oraz wyników badań prowadzonych na tym terenie w latach wcześniejszych. Pomiary wilgotności przeprowadzono metodą TDR w powierzchniowej warstwie gleby 0–25 cm oraz 25–50 cm, w kilkudziesięciu punktach (ok. 60) na terenie całego parku. Pozwoliło to na wygenerowanie map przestrzennego rozkładu uwilgotnienia gleby. Na ich podstawie stwierdzono, że na powierzchni parku występuje zauważalne zróżnicowanie zasobów retencji gromadzonych w glebie. Wyraźnie wyższe wartości uwilgotnienia obserwowano w pobliżu stawu parkowego. Przeprowadzone badania i analizy wskazują, że nadmierne uwilgotnienie w badanych profilach glebowych na terenie parku występuje zazwyczaj w okresie wiosennym i po nawalnych deszczach. Największy wpływ na kształtowanie zasobów retencji glebowej ma wielkość oraz rozkład opadów atmosferycznych.

EN

The paper presents the characteristics of water relations and assessment of changeability of soil retention resources in the Southern Park in Wrocław. The assessment was done on the basis of measurements of soil water content in 2012 and 2013 also the results of field investigations from earlier years were taken into account. The measurements of soil water content were done using TDR method in the upper soil layers 0–25 cm and 25–50 cm in several dozen points (about 60) on the area of Park. It allowed to generate the maps of spatial distribution of soil water content. It was found that on the area of park there was observable diversity of retention resources accumulated in soils. Explicitly higher values of moisture were observed in the vicinity of park pond. The researches and analyses showed that excessive water content in analyzed soils in the area of Park occurred usually in spring and after torrential rains. The value and distribution of precipitation had the highest influence on soil retention resources forming.

5

Dynamics of water content in light bare soil in summer half-year in the period of 2003–2012 and its agro-meteorological determinants

Biniak-Pieróg M.

Journal of Water and Land Development

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2014

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no. 22

41--50

EN

The objective of the study was the estimation of decade variation of water content in layers with thickness of 0–10, 0–20, 0–40 and 0–60 cm of a bare light brown soil in the summer half-year (May–October) in the 10- year period of 2003–2012 against the background of agro-meteorological conditions. The study was based on results of measurement of the moisture of a bare soil with the use of the TDR method, sums of atmospheric precipitations and ground water levels, conducted in the area of the Agro- and Hydrometeorology Observatory of the Wrocław University of Environmental and Life Sciences, situated in Wrocław-Swojec. The analyses revealed slight variation of mean decade values of water content in the bare soil in the summer half-year during the ten-year period under analysis. Irrespective of the thickness of the soil layer, precipitation in the 10-year period of 2003–2012 had a highly significant effect on the water content in the 2nd decade of July. In the case of soil layers with thickness down to 0–20 cm a statistically significant relation between soil water content and ground water levels was noted for the 3rd decade of May, July, and in the 3rd decade of September. In the layer with thickness of 0–60 cm the relations were statistically significant almost throughout the summer half-year, with the exception of the 1st and 2nd decades of May. Analysis of trends of mean water content of the bare soil over the 10-year period of 2003–2012 indicated their statistically significant increase in the case of most of the decades of the summer half-year only in soil layers with thickness of 0–10 and 0–20 cm.

PL

Celem pracy była ocena dekadowej zmienności zasobów wody w glebie lekkiej brunatnej nieporośniętej w półroczu letnim (maj–październik) w dziesięcioleciu 2003–2012 w warstwach miąższości 0–10, 0–20, 0–40 i 0–60 cm na tle warunków agrometeorologicznych. W pracy wykorzystano wyniki pomiarów wilgotności gleby nieporośniętej z zastosowaniem metody TDR, sum opadów atmosferycznych i stanów wody gruntowej, prowadzonych na terenie Obserwatorium Agro- i Hydrometeorologii Uniwersytetu Przyrodniczego we Wrocławiu- Swojcu. Przeprowadzone analizy wykazały nieznaczne wahania średnich dekadowych wartości zasobów wody gleby nieporośniętej w półroczu letnim w przyjętym do analiz 10-leciu. Bez względu na miąższość warstwy gleby opady atmosferyczne w okresie 2003–2012 istotnie wpływały na zasoby wody w 2. dekadzie lipca. W warstwach gleby o miąższości do 0–20 cm stwierdzono istotną statystycznie zależność zasobów wody w glebie i stanów wody gruntowej w 3. dekadzie maja, lipcu oraz 3. dekadzie września. W warstwie miąższości 0–60 cm relacje te były istotne statystycznie niemal w całym półroczu letnim, z wyjątkiem 1. i 2. dekady maja. Na podstawie analizy tendencji średnich zasobów wody w glebie nieporośniętej w okresie 10-lecia 2003–2012 stwierdzono ich istotny statystycznie wzrost w większości dekad półrocza letniego jedynie w warstwach gleby miąższości 0–10 i 0–20 cm.

6

In-situ measurements of moisture using surface TDR probes

Suchorab Z.

Rocznik Ochrona Środowiska

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2012

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Tom 14

107--122

EN

Problem of building barriers moisture is a well known phenomenon for almost all users of the buildings. Its presence is inevitable in moderate climate and its balanced states are acceptable. On the other hand, extended values of moisture are disadvantageous and may be caused by many factors like water vapor condensation inside the barriers, capillary rise of ground water, rainwater, inundations or sanitary systems failures. This phenomenon is also a factor which limits the object functionality both from the construction and sanitary-hygienic reasons. Extended moisture content problem is particularly visible in the historical buildings which were set up without the suitable horizontal water-proof isolations. In this cases, ground water has the unlimited access to the groundwork and then, due to the capillary forces to the internal parts of the walls. Increased amounts of water lead to the material structure destruction by melting and thawing processes during winter season, wood decay, and accelerated corrosion of steel reinforcement elements and crystallization of dissolved salts in transported water. Also it should be mentioned here, that indirectly, water negatively influences the indoor environment providing good conditions for harmful microorganisms and mould development which may consequently run to the respiratory system diseases, infections, allergies, eyes and skin irritations. All above presented negative consequences of water presence inside the building envelopes are the reason for constant development moisture detection techniques.

PL

Zjawisko zawilgocenia przegród budowlanych jest znane w zasadzie wszystkim użytkownikom obiektów budowlanych. Występowanie tego zjawiska jest praktycznie nie uniknione w warunkach klimatycznych w jakich znajduje się Polska. Jego zrównoważona obecność polegająca na ciągłym pochłanianiu wilgoci i jej odparowywaniu jest jak całkowicie akceptowalna. Szkodliwym jest natomiast zjawisko nadmiernej zawartości wilgoci, które może być wywołane wieloma czynnikami do których zaliczamy kondensację pary wodnej wewnątrz przegrody, podciąganie kapilarne wód gruntowych, wody rozbryzgowe z deszczy, wody powodziowe czy też awarie instalacji sanitarnych. Zjawisko powyższe jest niekorzystne z punktu widzenia budowli i jest czynnikiem ograniczającym funkcjonalność obiektu zarówno ze względów konstrukcyjnych, jak i higieniczno-sanitarnych. Problem nadmiernej zawartości wody w murach jest szczególnie widoczny w budynkach historycznych wznoszonych bez zastosowania właściwych izolacji poziomych. Wówczas woda gruntowa posiada nieograniczony dostęp do fundamentów budynku, a następnie przy udziale sił kapilarnych do wnętrza murów. Nadmierna ilość wody w zewnętrznych przegrodach budowlanych prowadzi do zniszczenia struktury materiału poprzez wielokrotne procesy zamarzania i rozmarzania w okresie zimowym, rozkład drewna, przyspieszoną korozja stalowych elementów zbrojeniowych oraz krystalizacja soli rozpuszczonych w transportowanej wodzie. Istotnym problemem jest również fakt, że woda pośrednio negatywnie oddziałuje na środowisko wewnętrzne pomieszczeń, przyczyniając się tym samym do rozwoju szkodliwych mikroorganizmów oraz grzybów pleśniowych. Może w konsekwencji przyczyniać się do chorób dróg oddechowych, infekcji, alergii oraz podrażnień oczu i skóry. Przedstawione powyżej negatywne skutki obecności wody w przegrodach budowlanych są podstawą do rozwoju i ciągłego opracowywania i udoskonalania technik detekcji wilgoci w przegrodach budowlanych. W niniejszym artykule przedstawiono możliwość przeprowadzenia badań in-situ przy zastosowaniu techniki pomiarowej TDR (Time Domain Reflectometry). Technika ta od wielu lat stosowana była do pomiarów wilgotności ośrodków gruntowych. Od początku XXI wieku trwały prace nad zastosowaniem techniki TDR do oceny zawilgocenia twardszych od gruntu materiałów i przegród budowlanych. Jednak inwazyjny charakter metody w większości przypadków uniemożliwiał jej praktyczne wykorzystanie lub był przyczyną wielu problemów technicznych. W ramach części badawczej artykułu przedstawiono pomiary wilgotności muru z cegły ceramicznej pełnej pokrytej warstwą tynku wapiennopiaskowego. Badany obiekt znajduje się na Lubelskiej starówce i jest to ściana bramy przy ul. Ku Farze. Jest to przegroda dotknięta zjawiskiem podciągania kapilarnego wynikającego z braku właściwych izolacji poziomych. Badania przeprowadzono w trzech terminach pomiarowych przy pomocy opracowanych na Politechnice Lubelskiej sond powierzchniowych TDR, umożliwiających bezinwazyjne pomiary wilgotności. W celu wykonania pomiarów, badaną przegrodę podzielono na charakterystyczne fragmenty tworzące siatkę pomiarową o określonych wymiarach. W trakcie eksperymentu w charakterystycznych punktach przegrody umieszczano czujnik i odczytywano parametry dielektryczne ośrodka, automatycznie przeliczając je na wilgotność objętościową. Wyniki przeprowadzonych badań naniesiono na siatkę pomiarów różnicując je kolorami w zależności od odczytanej wilgotności. Rezultatem powyższych zabiegów było uzyskanie tzw. map wilgotności przegrody budowlanej w trzech różnych terminach pomiarowych. Przedstawione w artykule mapy wilgotności potwierdzają fakt podwyższonej wilgotności przegrody i jednocześnie pozwalają na ukazanie jego rozkładu w pionie oraz poziomie. Przeprowadzone badania wyraźnie ukazują, że badana przegroda wykazuje nadmierną wilgotność w swych dolnych partiach, natomiast wyższe partie są nieco mniej wilgotne. Świadczy to o tym, że przyczyną nadmiernego zawilgocenia są wody gruntowe podciągane kapilarnie do wewnątrz struktury materiału. Wyniki badań przedstawione w artykule dowodzą skuteczności rozwijanych powierzchniowych sond TDR do bezinwazyjnego pomiaru wilgotności materiałów i przegród budowlanych oraz wskazują na przyczyny tego zjawiska w obiektach rzeczywistych.

7

Variation of sexual and clonal reproduction in Eremosparton songoricum (Litv.) (Fabaceae) on drought in arid regions : an experimental approach

Wang J., Shi X., Yin L., Zhang D.

Polish Journal of Ecology

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2012

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Vol. 60, nr 1

145-152

EN

Clonal plants combine sexual and clonal reproduction, which contribute differently to plant fitness. We investigated the consequence of natural selection on the two reproductive modes and the ecological factors that affect the reproductive modes of Eremosparton songoricum (Litv.) Vass. in order to understand the reproductive strategies of a clonal plant and the relationship between sexual and clonal reproduction. Morphological characteristics and biomass allocation patterns were m easured and compared at the clonal fragment level in two natural populations (riverside population A and hinterland population B) in the Gurbantunggut Desert, China. The flowering plant ratio, inflorescence number per plant, flower number per raceme, fruit number, mass of 100 seeds, root biomass, fruit biomass and ramet height were significantly higher, whereas fruit set, ramet density, rhizome biomass and length, and root number were significantly lower, in population A compared with those in population B. We estimated that the importance of clonal reproduction varies in two populations of E. songoricum, and the investment adjustment in the two reproductive modes may be based on cost required for each new plant to generate the more survival progeny in the plant life time.

8

Identyfikacja błędów pomiaru niskich wartości wilgotności gleby sondą reflektometryczną TDR

Skierucha W., Wilczek A.

Pomiary Automatyka Kontrola

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2010

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R. 56, nr 8

875-878

PL

W pracy podjęto próbę identyfikacji źródeł błędu pomiaru małych wartości wilgotności gleby sondą reflektometryczną TDR, które powstają na skutek efektu splotu sygnałów. Wykazano, że wybór mediów kalibracyjnych o wartościach przenikalności elektrycznej bliskich dolnemu i górnemu zakresowi pomiarowego przenikalności elektrycznej mierzonej gleby zmniejsza błąd pomiaru tej wielkości i w konsekwencji błąd pomiaru wilgotności gleby oraz umożliwia użycie sond TDR o różnych długościach prętów.

EN

Reflectometric TDR sensors working in time domain (TDR - Time Domain Reflectometry) are successfully used for laboratory and field measurements of the soil bulk dielectric permittivity and, indirectly, the soil water content. Commonly applied methods for calibrating these sensors use two media, in which the respective parallel waveguides of the TDR sensor are inserted into: air - for low and water - for high values of dielectric permittivity. However, the variability range of the soil bulk dielectric permittivity is much smaller than the one associated with these calibration media. Application of air to calibration of short TDR sensors causes output waveform overlapping errors of the pulse reflected from the rods beginning with the pulses reflected from the rods open termination, which results in a relative time shift of these pulses. In the paper there is shown the way how to minimise these errors, called convolution effect errors, by application of other than air and water calibration media. The authors try to identify the error sources of low soil water content values measured by a TDR reflectometric sensor caused by the convolution effect. It is shown that the proper choice of calibration media having dielectric permittivity values close to low and high limits of the measurement range of the measured porous medium (soil) decreases the dielectric permittivity measurement error and, consequently, the measurement error of water content as well as enables application of variable length TDR sensors.

9

Remediation of soils contaminated with trichloroethylene

Albergaria J. T., Alvim-Ferraz M. C. M., Delerue-Matos C. M.

Environmental Biotechnology

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2010

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Vol. 6, No. 2

37-41

EN

Soil contamination is a common problem in our society. Several activities introduce contaminants in soils affecting their quality and future utilization. In order to invert this situation and to avoid further spreading of the contaminant several remediation technologies could be used. For soils contaminated with trichloroethylene (TCE), Soil Vapor Extraction (SVE) can be an efficient remediation technology. It involves the application of vacuum to the soil matrix creating an airflow that conduce the volatized contaminant to extraction wells that lead them to the exterior of the soil where they are properly treated. This work presents the results obtained in the soil vapor experiments performed in a laboratory using soils with different water contents contaminated with TCE. These experiments aimed the study of the influence of soil water content and the airflow used in the remediation time and on the process efficiency. The results showed that in sandy soils contaminated with TCE: a) for similar levels of contamination, the increase of the soil water content from 0 to 4% created an increase of the concentration of TCE in the gas phase of the soil, in some cases by almost 50%; b) the influence of water content is not significant being overlapped by influence of the airflow rate; c) SVE performed with higher airflow rates had shorter remediation times (in some cases four times shorter) without any significant impact on the process efficiencies (fluctuations of 1 to 3%); and d) for the experimented soils, the utilization of higher airflow rates led to shorter and consequently cheaper remediation.

10

Altitudinal variability of the soil water content in natural and managed beech (Fagus sylvatica L.) forests

Pichler V., Durkovic J., Capuliak J., Pichlerova M.

Polish Journal of Ecology

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2009

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Vol. 57, nr 2

313-319

EN

European beech (Fagus sylvatica L.) ranks as one of the most adaptive species among European indigenous trees. Variable interactions between the trees and soil water depend on both phenotypic plasticity of the species and natural conditions. They are controlled through stomatal regulation and the ability of beech trees to accelerate quickly their growth if available resources increase. However, the effect of forest density at various altitudes on the soil water content in beech stands has been studied rather scarcely. Therefore, we monitored soil moisture by means of Time Domain Reflectometry in series of natural and managed stands located on sites representing the lower altitude (200-550 m a.s.l.), middle altitude (550-1050 m a.s.l.) and higher altitude (1050-1300 m a.s.l.) zones of the natural beech belt in the Western Carpathians, Slovakia. Forest stand density, expressed in terms of basal area, i.e. the sum of cross section areas of the tree stems at 1.30 m height, was unchanged in natural stands, but it was reduced by 60% in the shelterwood stands. In the clear-cuts, all trees were removed. Total soil water content (SWC) under forest stands was calculated in mm as the product of soil moisture and soil depth, the latter acquired by electrical resistivity tomography. SWC differences between natural and shelterwood stands of the lower altitude, middle altitude and higher altitude zones averaged 18 mm, 36 mm and -3 mm, respectively. According to the Friedman test on ranks, followed by post-hoc multiple comparison testing, the difference was only significant within the middle altitude zone. In it, soil water consumption by the natural stand was limited only by the hormonally controlled seasonal regulation. The comparatively low water loss in the shelterwood stand resulted from a small rainfall interception by forest canopy and a decreased soil water uptake due to reduced basal area, leaf area index and simple age-size forest structure. In the lower altitude zone, the precipitation deficit and limited extractability of soil water were responsible for the absence of larger SWC differences. As opposed to that, low potential evapotranspiration prevented any noticeable SWC differences within the higher altitude zone.

11

Design, construction and performance of a pressure chamber for water retention curve determination through traditional and nuclear methods

Pires L., Bacchi O.

Nukleonika

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2006

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Vol. 51, nr 4

225-230

EN

We present in this work a detailed design of a small low-pressure chamber outfitted with a ceramic porous plate for evaluating the soil water retention curve (SWRC) in the water potential range from 0 to -100 kPa. The chamber is made of acrylic and permits the use of one unique soil sample each time. The use of this chamber allows quick measurements of soil moisture using nuclear (based on gamma-ray attenuation) and conventional methods and SWRC determinations made with the designed chamber are in agreement with those obtained using a commercial low-pressure chamber. The chamber was designed especially for testing the use of the nuclear method as an auxiliary tool for SWRC determinations but it can be easily adapted for routine investigations and a practical alternative for the conventional SWRC method.

12

Characteristics of diurnal water loss of five adjacent ecosystems at Changbai Mountains in Northeast China

Chen X., Li B.

Polish Journal of Ecology

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2004

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Vol. 52, nr 3

323-331

EN

Changes in ecosystem water consumption and hydrological processes following ecosystem alterations are important for environmental management and regional water supply. In this study on relatively dry days, the temporal dynamics of diurnal soil water contents at different soil depths were investigated within five adjacent ecosystems (primary forest and four ecosystems changed from the primary forest after human disturbance - clear-cut, grassland, shrub and secondary forest) at the altitude around 700 m a.s.l. at Changbai Mountain in Northeast China. On July 17, 2001 the diurnal water loss in the clear-cut was the highest among the five ecosystems and reached about 3.74x10^5 kg ha^-1, and it was lowest and about 1.07x10^5 kg ha^-1 in the primary forest of mixed broadleaved Korean pine forest. The temporal dynamics of soil water contents at different depths in the studied ecosystems were complicated but there were some common characteristics. First, soil water contents were higher at soil surface (about 0-10 cm) and then decreased with the soil depths. Second, soil moisture fluctuations were most rapid in the depths of 0-10 cm and 10-20 cm, and were comparatively slow and more moderate at the greater depths. The spatial and temporal changes of soil water content might be related with aboveground plants. Therefore, after the primary forest was converted to other ecosystems the hydrological characteristics of the ecosystem were changed, which would potentially affect regional hydrological processes.

13

Impact of quantity and intensity of rainfall on soil water content in an orchard located in the central part of Poland

Treder W., Konopacki P.

Journal of Water and Land Development

|

1999

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no. 3

47-58

EN

The measurement of water used by plants is a decisive factor for calculation of irrigation rates, and generally the need of irrigation. Quantity, intensity and seasonal distribution of precipitation have an indubitable impact on soil moisture. Precipitation water could be used by plants only when percolates into soil and is retained as capillary water. Unfortunately, in case of excessive amount or intensity of rain, part of water percolates below the root system range or runs off at soil surface. During three years of experiment (1995-1997) quantity and intensity of precipitation were observed and weekly measurements of soil moisture at different orchard layouts were done. On the basis of collected data, the analyses of impact of quantity and intensity of precipitation on soil moisture changes in orchard were conducted. The results indicate low efficiency of small rains (smaller than daily potential evapotranspiration). Relatively small efficiency was found also for stormy rains, whose contribution to the total amount of precipitation during vegetative period was from 20 % up to 36 %. Efficiency of precipitation depended also on initial soil moisture, which was the reason of high differences in influence of precipitation amounts on changes of water content in soil profile in irrigated and non-irrigated orchards.

PL

Pomiar zużycia wody przez rośliny uprawne ma decydujące znaczenie dla określenia wielkości i celowości nawadniania. Ilość i intensywność oraz rozkład opadów mają niewątpliwy wpływ na wilgotność gleby. Woda opadowa może być wykorzystywana przez rośliny tylko wtedy gdy wsiąknie do gleby i jest w niej retencjonowana jako woda kapilarna. Niestety, w przypadku obfitości lub nadmiernej intensywności opadów część wody może przesiąkać poza zasięg systemu korzeniowego lub odprowadzana jest z pola poprzez spływ powierzchniowy. W trakcie trzyletnich badań (1995-1997) prowadzono pomiary wielkości i intensywności opadów oraz cotygodniowe pomiary wilgotności gleby w różnych nasadzeniach sadowniczych. Na podstawie otrzymanych wyników przeprowadzono analizę wpływu wielkości i intensywności opadów na zmiany wilgotności gleby w sadzie. Wyniki tych analiz wskazują na małą efektywność opadów niskich (poniżej wysokości dziennej ewapotranspiracji potencjalnej). Stosunkowo małą efektywnością charakteryzują się także opady burzowe których udział w całkowitej ilości opadów w okresie wegetacji stanowił aż 20 do 36%. Efektywność opadów zależna była także od początkowej wilgotności gleby, co było powodem znacznych różnic we wpływie wielkości opadów na zmiany bilansu wodnego profilu glebowego sadów nawadnianych i kontrolnych.