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Assessing water content

Assessing water content

The complete drying Assessing water content of a soil sample in Aseessing conventional conten oven for twenty-four hours is the core of this standard. ASTM D defines a treatment method to squeeze pore water from fine-grained soils. Sacks 4.

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Moisture Content and Water Activity

Assessing water content -

The development of systems for monitoring different parameters to detect extreme hydrological situations and water stress is being attempted on several scales in Europe e.

For agriculture, information on soil moisture as well as temperature and precipitation conditions is important given that even at 70—cm-depth soil can get extremely dried out and influence vegetation growth. Instead, of providing volumetric water content, the calculation of appropriately selected soil moisture indices and anomalies can effectively support the agricultural stakeholders.

Effective crop production aims to optimise irrigation time and the amount of applied water to prevent losses and conserve water resources Datta et al. The aim of this study has been to analyse the effects of changes in soil moisture conditions on Arenosols, formed from blown sand in the Great Hungarian Plain and characterised by an unfavourable soil moisture regime.

These soils are highly exposed to fluctuating weather conditions, and, owing to their high permeability, they tend to dry out rapidly in drought periods; thus the impact of water shortage is relatively temporary.

Using a classification of AW content of the soil, we evaluated the rate, time and duration of water shortage for the period — and assessed its efficiency for integration with an online monitoring system.

The degree of a drought is characterised not only by meteorological parameters and measured soil moisture data but also by the relation between soil moisture and significant points along the pF curve. This study concerns only sandy soils, but the assessment can be extended to other soil textures, and how different soils behave under drought conditions could be compared objectively.

We investigated water availability for agriculture during — in two study areas in southern Hungary in Kelebia and Kiskundorozsma where Arenosols had developed from windblown sands Fig. They belong to the Köppen-Cf or Trewartha-D.

In past decades, these areas were hit by severe droughts about every three to five years e. In an earlier survey, farmers and decision makers in the region indicated concern about the adverse effects of drought and emphasised the significant role of sandy soils and the lowered groundwater table Blanka et al.

Location of soil moisture network in Hungary HU and two study areas Kelebia HU02 and Kiskundorozsma HU Both stations are on unnatural grasslands that are regularly managed by mowing. The grassland in the Kelebia study area was rainfed during —, whereas in the Kiskundorozsma area, it was regularly irrigated during — and was rainfed during — The Kelebia station is on the Danube—Tisza Interfluve and at a higher elevation m ASL compared to the Kiskundorozsma station 79m ASL.

The groundwater table was deeper than 2 m below the surface in the Kelebia case throughout the investigated period, whereas in the case of Kiskundorozsma, the groundwater or capillary zone could reach the subsoil in humid years.

The soil moisture data used in this study were provided by a hydrometeorological station network installed in Fig. We calculated daily averages from the available hourly data for the period — The dataset was almost continuous; data gaps were due to technical problems.

For FC, the measured pF2 value was applied, and for WP, the value pF4. The infiltration and drying-out processes were monitored on soil profiles of extreme water balance in years that experienced different hydrological conditions. For monitoring and characterising drought, the basic question always concerns where is the soil moisture positioned between FC and WP.

The classification thresholds were confirmed by previous research in the field. According to Datta et al. Using this classification, the time and durations of water-shortage periods were evaluated for the period — Drying-out and infiltration processes in the soil profile can also be studied by the soil moisture data from six depths.

By comparing soil moisture and precipitation data, the relation between precipitation and soil moisture changes can be identified. By multiplying the thickness of the given soil layer by the difference between FC and actual soil moisture, we estimated water scarcity mm and summarised the water deficit for the whole cm soil profile:.

Thus, quantification of water scarcity was done by calculating the necessary infiltration mm to reach FC. Because the upper sensors in the area are at cm distances and the lower ones are at cm distances, 1 and 1.

The differences in soil properties and management between the two study areas were quantified by duration curves for both soil profiles.

On the curves, water scarcity conditions exist toward the right; the lowest values at the extreme right may represent extreme water scarcity or data failure due to frost. To determine drought conditions, the duration and timing of high and extreme water shortage in the soil profile was evaluated.

We determined the number of days when soil-water shortage was high or extreme during the whole investigated profile, calculated their duration as a percentage of the vegetation period and compared their timing across the investigated years.

However, the upper two sensors experience extremely dry conditions and show more frequent fluctuations compared to the subsoil sensors, which show steadier water-condition changes. When we compared consecutive years, only could be characterised by somewhat-favourable soil moisture during the vegetation period, given that soil moisture increases several times while the upper-soil sensors are reaching the critical values owing to the more frequent rains and while the subsoil sensor values are generally fluctuating around the FC.

In all the other investigated years, extreme water scarcity is characteristic for a significant portion of the vegetation period, especially as measured by the subsoil sensors. We observed that water mostly reached only the upper 20—30 cm during the experienced rainfalls; also, subsoil sensors are near the WP after the first two months of the vegetation period and thus cannot help the vegetation survive.

The best example of such a winter anomaly was soil frost that occurred in a transition period during — and was readily observable in both the Kelebia HU02 and the Kiskundorozsma HU1 data. A major difference between the datasets of the two study areas is the impact of irrigation during — In Kiskundorozsma, because soil-water household was improved daily by irrigation, we find hardly any evidence of a long-lasting extreme water shortage in the soil profile.

Instead, the subsoil sensors were almost saturated or even oversaturated several times, which might mean that groundwater could be another reason for the constantly higher values.

Furthermore, during —, when there was no extra water supply from irrigation, subsoil sensors often showed higher values and steadier water conditions compared to the upper-soil sensors.

Without input from irrigation, these periodic changes possibly were caused by the seasonal lowering of the capillary zone groundwater table.

Figure 3 represents the infiltration of rainwater in the soil profile in Kelebia HU02 , and it is clearly visible how water shortage evolves in the subsoil layers in almost all vegetation periods. Because neither groundwater nor capillary water reaches the subsoil layers, soil moisture becomes only minimally available for vegetation for most of the period.

Therefore, agriculture and the inhabitants in the study area and also in the wider region with Arenosols become really vulnerable to the extreme water conditions. Up to the FC, this soil is able to store 90mm moisture in Kelebia HU It means that within the investigated period in this case one third of the storable water up to FC could be reached in a period of drought.

Daily precipitation mm and soil-water shortage at different depths through entire investigated soil profile in Kelebia HU02 [WS, water shortage]. The impact of irrigation on the soil-water household is readily observable in Fig.

During —, as a result of the lack of irrigation, the upper soil experienced extreme water shortage, but the subsoil was characterised by higher soil moisture content in the spring and early summer due to capillary water.

However, toward the end of summer, extreme water shortage was observed in the investigated profile. According to the summarised soil-water shortage based on the profile, it remained within 0—50 mm during — in the vegetation period.

However, based on the — data, the water from the soil profile reached and maintained 50 mm until the end of the vegetation period, comparable to the Kelebia site. However, comparing the two Arenosols shows higher vulnerability in Kiskundorozsma HU The difference between the soils is the humus content of the upper soil 0—10 cm , which is higher 2.

Daily precipitation mm and soil-water shortage at different depths through entire investigated soil profile in Kiskundorozsma HU The differences between the two stations that are due to the irrigation at HU01 are evident in the separate duration curves for the two time periods — and — Fig.

In the rainfed Kelebia HU02 station, the order of the sensors is almost the same in drought and wet years. The topsoil generally dries earlier than the subsoil, and in drought years second time period the subsoil also shows longer water-shortage periods, thus the sensors of the upper soils and subsoils show less difference.

In the years when irrigation was applied in the case of HU01 , the normal order of the duration curves changed, and the upper sensors showed the highest AW contents. In years without irrigation, the order of the sensors is similar for the two areas, and the lowest sensors show higher wetness for longer periods.

These data assume downward water input, but the soil may get wet by capillary rise. Also, the values near or below zero may reflect either soil frost or extreme drought.

Duration curves for Kelebia HU02 and Kiskundorozsma HU01 for periods — A and C and — B and D representing non-irrigated period for both stations. Horizontal axis represents duration days when soil moisture was higher than percentage shown. The duration and timing of high and extreme water shortage in the soil profile are important for determining drought conditions.

In all other investigated years Fig. Because this dry year was compensated in the Kiskundorozsma case by irrigation, no days occurred when the whole profile was under high or extreme water shortage.

Water was missing from the whole soil profile for long periods in the cases of rainfed sandy soil, which affected all types of plants and crops. Because the longer water-shortage period in the whole soil profile was shifted to the second part of the vegetation period in , those plants that require water in spring and early summer could survive; however, the long dry period significantly affected plants or other crops.

Our results of available soil-water content for two sandy soils in southern Hungary show that of the five investigated years, four were affected by high and extreme water shortage threatening agricultural production without irrigation.

For a significant part of the vegetation period, the whole soil profile down to 75 cm became dry, which cannot easily be reversed by single rainfall events; only durable autumn and winter precipitation can replace the water without irrigation. The study calls attention to detailed monitoring of environmental parameters and the assessment of inter-annual patterns.

The countrywide drought extent and county-scale crop-yield data Table 3 highlight only the extremes of and , which tends to mask territorial vulnerability. According to our investigations, was hit by an extreme drought, but owing to the higher AW in the soil as a result of the previous humid year, the period of high and extreme water shortage started later, thereby mitigating early spring conditions for the vegetation.

This confirms that soil moisture is an essential parameter to characterise drought conditions. In this study, total water shortage mm in the soil profile was given for both profiles, but the data are not comparable without the detailed knowledge of the soil parameters, given that they highly influence plant-water uptake.

The introduced classification of water shortage in the soil may better support agrarian water management. Because the rate and frequency of drought is predicted to increase and summer precipitation is expected to decrease in the future Bartoly et al.

As our study reflected, drought monitoring cannot be effective without monitoring of soil-moisture content.

Based on this method, a new national drought-monitoring system was put in place in Hungary starting in The novelty of this system is that the applied drought index Hungarian Drought Index, HDI can distinguish between different soil types even under the same meteorological conditions Fiala et al.

Detailed analysis of AW can be used in real-time drought monitoring and can precisely indicate the evolution of drought differentiated by various soil types, which can help us manage or prevent damage from drought.

The installed complex monitoring stations already exceeded in , and the provided data form the basis of daily updated drought information for the whole country ODWMS The authors confirm that the data supporting the findings of this study are available within the article or could be requested from the corresponding author, upon reasonable request.

ATIVIZIG Lower-Tisza District Water Directorate. Accessed 13 Dec Barta K, Crnojevic VB, Blanka V, Ladányi Zs, Fiala K, Vukobratovic D Possibilities of field measurement of soil moisture. In: Blanka V, Ladányi Zs eds Drought and water management in South Hungary and Vojvodina.

University of Szeged, Szeged, pp — Google Scholar. Bartholy J, Pongrácz R, Gelybó G, Szabó P Analysis of expected climate change in the Carpathian Basin using the PRUDENCE results Időjárás — Bilskie J Soil water status: content and potential.

Campbell Scientific, Inc. Accessed 12 Nov Blanka V, Mezősi G, Meyer B Changes in the drought hazard in Hungary due to climate change. Időjárás — Blanka V, Ladányi Z, Szilassi P, Sipos Gy, Rácz A, Szatmári J Public perception on hydro-climatic extremes and water management related to environmental exposure, SE Hungary.

Water Resour Manag — Article Google Scholar. Bucur A, Gregorič G, Grlj A, Kokalj Ž, Sušnik A Tool for drought monitoring in the Danube region — methods and preliminary developments.

J Environ Geol — Chaves MM, Costa JM, Madeira Saibo NJ Recent advances in photosynthesis under drought and salinity.

In: Turkan, I. Plant responses to drought and salinity stress. Developments in a Post-Genomic Era. Advances in Botanical Research — Datta S, Taghvaeian S, Stivers J Understanding soil water content and thresholds for irrigation management.

Oklahoma Cooperative Extension Service, BAE 1—8. Djordjević SV Temperature and precipitation trends in Belgrade and indicators of changing extremes for Serbia.

Geographica Pannonica — Dunay S, Kalmár E A talajvízszint szerepe a talajok vízháztartásában. Éghajlati és agrometeorológiai tanulmányok sorozat. Országos Meteorológiai Szolgálat, Budapest, pp 43— Fiala K, Blanka V, Ladányi Z, Szilassi P, Benyhe B, Dolinaj D, Pálfai I Drought severity and its effect on agricultural production in the Hungarian-Serbian cross-border area.

Fiala K, Barta K, Benyhe B, Fehérváry I, Lábdy J, Sipos Gy, Győrffy L Operatív aszály-és vízhiánykezelő monitoring rendszer. Hidrológiai Közlöny — HCSO Database of the Hungarian Central Statistical Office. Hatfield JL True Value of Carbon in Agricultural Soils. South Dakota No Till Association Annual Conference pp.

IPCC Global warming of 1. IPCC Special Report. Iglesias A, Garrote L, Flores F, Moneo M Challenges to manage the risk of water scarcity and climate change in the Mediterranean. Iglesias A, Santillán D, Garrote L On the barriers to adaption to less water under climate change: policy choices in Mediterranean Countries.

Weighed samples are placed under reduced pressure typically mm Hg in a vacuum oven for a specified time and temperature and their dried mass is determined. The thermal energy used to evaporate the water is applied directly to the sample via the metallic shelf that it sits upon.

There is an air inlet and outlet to carry the moisture lost from the sample out of the vacuum oven, which prevents the accumulation of moisture within the oven.

The boiling point of water is reduced when it is placed under vacuum. Drying foods in a vacuum oven therefore has a number of advantages over conventional oven drying techniques.

If the sample is heated at the same temperature, drying can be carried out much quicker. Alternatively, lower temperatures can be used to remove the moisture e.

A number of vacuum oven methods are officially recognized. Microwave oven. Weighed samples are placed in a microwave oven for a specified time and power-level and their dried mass is weighed.

Alternatively, weighed samples may be dried until they reach a constant final mass - analytical microwave ovens containing balances to continuously monitor the weight of a food during drying are commercially available.

The water molecules in the food evaporate because they absorb microwave energy, which causes them to become thermally excited. The major advantage of microwave methods over other drying methods is that they are simple to use and rapid to carry out.

Nevertheless, care must be taken to standardize the drying procedure and ensure that the microwave energy is applied evenly across the sample. A number of microwave oven drying methods are officially recognized. Infrared lamp drying.

The sample to be analyzed is placed under an infrared lamp and its mass is recorded as a function of time. The water molecules in the food evaporate because they absorb infrared energy, which causes them to become thermally excited. One of the major advantages of infrared drying methods is that moisture contents can be determined rapidly using inexpensive equipment, e.

This is because the IR energy penetrates into the sample, rather than having to be conducted and convected inwards from the surface of the sample.

To obtain reproducible measurements it is important to control the distance between the sample and the IR lamp and the dimensions of the sample. IR drying methods are not officially recognized for moisture content determinations because it is difficult to standardize the procedure.

Even so, it is widely used in industry because of its speed and ease of use. The water that is released by this reaction is not the water we are trying to measure and would lead to an overestimation of the true moisture content. On the other hand, a number of chemical reactions that occur at elevated temperatures lead to water absorption, e.

Foods that are particularly susceptible to thermal decomposition should be analyzed using alternative methods, e.

chemical or physical. Distillation Methods. Basically, distillation methods involve heating a weighed food sample M INITIAL in the presence of an organic solvent that is immiscible with water.

The water in the sample evaporates and is collected in a graduated glass tube where its mass is determined M WATER. Distillation methods are best illustrated by examining a specific example: the Dean and Stark method.

A known weight of food is placed in a flask with an organic solvent such as xylene or toluene. The organic solvent must be insoluble with water; have a higher boiling point than water; be less dense than water; and be safe to use. The flask containing the sample and the organic solvent is attached to a condenser by a side arm and the mixture is heated.

The water in the sample evaporates and moves up into the condenser where it is cooled and converted back into liquid water, which then trickles into the graduated tube. When no more water is collected in the graduated tube, distillation is stopped and the volume of water is read from the tube.

There are a number of practical factors that can lead to erroneous results: i emulsions can sometimes form between the water and the solvent which are difficult to separate; ii water droplets can adhere to the inside of the glassware, iii decomposition of thermally labile samples can occur at the elevated temperatures used.

Chemical Reaction Methods. Reactions between water and certain chemical reagents can be used as a basis for determining the concentration of moisture in foods.

In these methods a chemical reagent is added to the food that reacts specifically with water to produce a measurable change in the properties of the system, e. Measurable changes in the system are correlated to the moisture content using calibration curves. To make accurate measurements it is important that the chemical reagent reacts with all of the water molecules present, but not with any of the other components in the food matrix.

Two methods that are commonly used in the food industry are the Karl-Fisher titration and gas production methods. Chemical reaction methods do not usually involve the application of heat and so they are suitable for foods that contain thermally labile substances that would change the mass of the food matrix on heating e.

spices and herbs. The Karl-Fisher titration is often used for determining the moisture content of foods that have low water contents e.

dried fruits and vegetables, confectionary, coffee, oils and fats. It is based on the following reaction:. This reaction was originally used because HI is colorless, whereas I 2 is a dark reddish brown color, hence there is a measurable change in color when water reacts with the added chemical reagents.

Sulfur dioxide and iodine are gaseous and would normally be lost from solution. For this reason, the above reaction has been modified by adding solvents e.

The food to be analyzed is placed in a beaker containing solvent and is then titrated with Karl Fisher reagent a solution that contains iodine. While any water remains in the sample the iodine reacts with it and the solution remains colorless HI , but once all the water has been used up any additional iodine is observed as a dark red brown color I 2.

The volume of iodine solution required to titrate the water is measured and can be related to the moisture content using a pre-prepared calibration curve. The precision of the technique can be improved by using electrical methods to follow the end-point of the reaction, rather than observing a color change.

Relatively inexpensive commercial instruments have been developed which are based on the Karl-Fisher titration, and some of these are fully automated to make them less labor intensive. Commercial instruments are also available that utilize specific reactions between chemical reagents and water that lead to the production of a gas.

For example, when a food sample is mixed with powdered calcium carbide the amount of acetylene gas produced is related to the moisture content. The amount of gas produced can be measured in a number of different ways, including i the volume of gas produced, ii the decrease in the mass of the sample after the gas is released, and iii the increase in pressure of a closed vessel containing the reactants.

A number of analytical methods have been developed to determine the moisture content of foods that are based on the fact that water has appreciably different bulk physical characteristics than the food matrix, e. density, electrical conductivity or refractive index. These methods are usually only suitable for analysis of foods in which the composition of the food matrix does not change significantly, but the ratio of water-to-food matrix changes.

For example, the water content of oil-in-water emulsions can be determined by measuring their density or electrical conductivity because the density and electrical conductivity of water are significantly higher than those of oil.

If the composition of the food matrix changes as well as the water content, then it may not be possible to accurately determine the moisture content of the food because more than one food composition may give the same value for the physical property being measured.

In these cases, it may be possible to use a combination of two or more physical methods to determine the composition of the food, e. Spectroscopic methods utilize the interaction of electromagnetic radiation with materials to obtain information about their composition, e.

The spectroscopic methods developed to measure the moisture content of foods are based on the fact that water absorbs electromagnetic radiation at characteristic wavelengths that are different from the other components in the food matrix.

The most widely used physical methods are based on measurements of the absorption of microwave or infrared energy by foods. The analysis is carried out at a wavelength where the water molecules absorb radiation, but none of the other components in the food matrix do.

A measurement of the absorption of radiation at this wavelength can then be used to determine the moisture content: the higher the moisture content, the greater the absorption.

Instruments based on this principle are commercially available and can be used to determine the moisture content in a few minutes or less. It is important not to confuse infrared and microwave absorption methods with infrared lamp and microwave evaporation methods.

The former use low energy waves that cause no physical or chemical changes in the food, whereas the latter use high-energy waves to evaporate the water. The major advantage of these methods is that they are capable of rapidly determining the moisture content of a food with little or no sample preparation and are therefore particularly useful for quality control purposes or rapid measurements of many samples.

The overall water content of a food is sometimes not a very reliable indication of the quality of a food because the water molecules may exist in different environments within foods, e. Here "bound water" refers to water that is physically or chemically bound to other food components, whereas "free water" refers to bulk, capillary or entrapped water.

For example, the microbial stability or physicochemical properties of a food are often determined by the amount of free water present, rather than by the total amount of water present.

For this reason, it is often useful for food scientists to be able to determine the amount of water in different molecular environments within a food. A variety of analytical methods are available that can provide this type of information.

A physical parameter that is closely related to the amount of free water present in a food is the water activity:. where, P is the partial pressure of the water above the food and P 0 is the vapor pressure of pure water at the same temperature. Bound water is much less volatile than free water, and therefore the water activity gives a good indication of the amount of free water present.

A variety of methods are available for measuring the water activity of a sample based on its vapor pressure. Usually, the sample to be analyzed is placed in a closed container and allowed to come into equilibrium with its environment.

The water content in the headspace above the sample is then measured and compared to that of pure water under the same conditions.

Thermogravimetric techniques can be used to continuously measure the mass of a sample as it is heated at a controlled rate.

The temperature at which water evaporates depends on its molecular environment: free water normally evaporates at a lower temperature than bound water. Thus by measuring the change in the mass of a sample as it loses water during heating it is often possible to obtain an indication of the amounts of water present in different molecular environments.

Calorimetric techniques such as differential scanning calorimetry DSC and differential thermal analysis DTA can be used to measure changes in the heat absorbed or released by a material as its temperature is varied at a controlled rate.

The melting point of water depends on its molecular environment: free water normally melts at a higher temperature than bound water. Thus by measuring the enthalpy change of a sample with temperature it is possible to obtain an indication of the amounts of water present in different molecular environments.

The electromagnetic spectrum of water molecules often depends on their molecular environment, and so some spectroscopy techniques can be used to measure the amounts of water in different environments.

One of the most widely used of these techniques is nuclear magnetic resonance NMR. NMR can distinguish molecules within materials based on their molecular mobility, i. The molecular mobility of free water is appreciably higher than that of bound water and so NMR can be used to provide an indication of the concentrations of water in "free" and "bound" states.

Determination of Moisture and Total Solids 3. It is important to food scientists for a number of different reasons: Legal and Labeling Requirements.

There are legal limits to the maximum or minimum amount of water that must be present in certain types of food. The cost of many foods depends on the amount of water they contain - water is an inexpensive ingredient, and manufacturers often try to incorporate as much as possible in a food, without exceeding some maximum legal requirement.

Microbial Stability. The propensity of microorganisms to grow in foods depends on their water content. For this reason many foods are dried below some critical moisture content. Food Quality. The texture, taste, appearance and stability of foods depends on the amount of water they contain.

Food Processing Operations. A knowledge of the moisture content is often necessary to predict the behavior of foods during processing, e. mixing, drying , flow through a pipe or packaging. The water molecules in these different environments normally have different physiochemical properties: Bulk water.

Bulk water is free from any other constituents, so that each water molecule is surrounded only by other water molecules.

It therefore has physicochemical properties that are the same as those of pure water, e. Capillary or trapped water. Capillary water is held in narrow channels between certain food components because of capillary forces.

Trapped water is held within spaces within a food that are surrounded by a physical barrier that prevents the water molecules from easily escaping, e. The majority of this type of water is involved in normal water-water bonding and so it has physicochemical properties similar to that of bulk water.

Physically bound water. A significant fraction of the water molecules in many foods are not completely surrounded by other water molecules, but are in molecular contact with other food constituents, e.

proteins, carbohydrates or minerals.

Determination of Moisture and Total Solids. Moisture content contnet one Assessing water content the most commonly measured properties of wter materials. It is important to Website performance optimization tools scientists for wqter number of different reasons:. It Assessing water content therefore important for food scientists to be able to reliably measure moisture contents. A number of analytical techniques have been developed for this purpose, which vary in their accuracy, cost, speed, sensitivity, specificity, ease of operation, etc. The choice of an analytical procedure for a particular application depends on the nature of the food being analyzed and the reason the information is needed. Assessing water content In Assessing water content future, according to regional climate-model simulations, Fuel your Day with Nuts Assessing water content Asseseing Assessing water content Central Europe is contentt to be exposed to intensifying weather extremes Asaessing will exert a growing pressure Assessing water content water resources. In recent past decades, water already has Assesding a significant limiting Assessing water content for the natural Assexsing and many agro-economic sectors in the southern Carpathian Basin. Therefore, there are increasing attempts to develop monitoring systems to detect water stress. In this study, changes in soil moisture conditions were monitored within two Arenosol profiles of extreme water balance during years characterised by different hydrologic conditions and under the impact of irrigation in the Great Hungarian Plain. Hourly data series of hydrometeorological parameters and soil moisture from six different soil depths during — were provided by on-site monitoring stations; humus, carbonate content, porosity, field capacity and wilting point were measured in the laboratory. The results show that drought monitoring cannot be effective without investigation of soil moisture content.

Assessing water content -

The grassland in the Kelebia study area was rainfed during —, whereas in the Kiskundorozsma area, it was regularly irrigated during — and was rainfed during — The Kelebia station is on the Danube—Tisza Interfluve and at a higher elevation m ASL compared to the Kiskundorozsma station 79m ASL.

The groundwater table was deeper than 2 m below the surface in the Kelebia case throughout the investigated period, whereas in the case of Kiskundorozsma, the groundwater or capillary zone could reach the subsoil in humid years.

The soil moisture data used in this study were provided by a hydrometeorological station network installed in Fig. We calculated daily averages from the available hourly data for the period — The dataset was almost continuous; data gaps were due to technical problems.

For FC, the measured pF2 value was applied, and for WP, the value pF4. The infiltration and drying-out processes were monitored on soil profiles of extreme water balance in years that experienced different hydrological conditions.

For monitoring and characterising drought, the basic question always concerns where is the soil moisture positioned between FC and WP. The classification thresholds were confirmed by previous research in the field. According to Datta et al.

Using this classification, the time and durations of water-shortage periods were evaluated for the period — Drying-out and infiltration processes in the soil profile can also be studied by the soil moisture data from six depths.

By comparing soil moisture and precipitation data, the relation between precipitation and soil moisture changes can be identified. By multiplying the thickness of the given soil layer by the difference between FC and actual soil moisture, we estimated water scarcity mm and summarised the water deficit for the whole cm soil profile:.

Thus, quantification of water scarcity was done by calculating the necessary infiltration mm to reach FC. Because the upper sensors in the area are at cm distances and the lower ones are at cm distances, 1 and 1.

The differences in soil properties and management between the two study areas were quantified by duration curves for both soil profiles. On the curves, water scarcity conditions exist toward the right; the lowest values at the extreme right may represent extreme water scarcity or data failure due to frost.

To determine drought conditions, the duration and timing of high and extreme water shortage in the soil profile was evaluated. We determined the number of days when soil-water shortage was high or extreme during the whole investigated profile, calculated their duration as a percentage of the vegetation period and compared their timing across the investigated years.

However, the upper two sensors experience extremely dry conditions and show more frequent fluctuations compared to the subsoil sensors, which show steadier water-condition changes. When we compared consecutive years, only could be characterised by somewhat-favourable soil moisture during the vegetation period, given that soil moisture increases several times while the upper-soil sensors are reaching the critical values owing to the more frequent rains and while the subsoil sensor values are generally fluctuating around the FC.

In all the other investigated years, extreme water scarcity is characteristic for a significant portion of the vegetation period, especially as measured by the subsoil sensors.

We observed that water mostly reached only the upper 20—30 cm during the experienced rainfalls; also, subsoil sensors are near the WP after the first two months of the vegetation period and thus cannot help the vegetation survive. The best example of such a winter anomaly was soil frost that occurred in a transition period during — and was readily observable in both the Kelebia HU02 and the Kiskundorozsma HU1 data.

A major difference between the datasets of the two study areas is the impact of irrigation during — In Kiskundorozsma, because soil-water household was improved daily by irrigation, we find hardly any evidence of a long-lasting extreme water shortage in the soil profile. Instead, the subsoil sensors were almost saturated or even oversaturated several times, which might mean that groundwater could be another reason for the constantly higher values.

Furthermore, during —, when there was no extra water supply from irrigation, subsoil sensors often showed higher values and steadier water conditions compared to the upper-soil sensors.

Without input from irrigation, these periodic changes possibly were caused by the seasonal lowering of the capillary zone groundwater table. Figure 3 represents the infiltration of rainwater in the soil profile in Kelebia HU02 , and it is clearly visible how water shortage evolves in the subsoil layers in almost all vegetation periods.

Because neither groundwater nor capillary water reaches the subsoil layers, soil moisture becomes only minimally available for vegetation for most of the period. Therefore, agriculture and the inhabitants in the study area and also in the wider region with Arenosols become really vulnerable to the extreme water conditions.

Up to the FC, this soil is able to store 90mm moisture in Kelebia HU It means that within the investigated period in this case one third of the storable water up to FC could be reached in a period of drought. Daily precipitation mm and soil-water shortage at different depths through entire investigated soil profile in Kelebia HU02 [WS, water shortage].

The impact of irrigation on the soil-water household is readily observable in Fig. During —, as a result of the lack of irrigation, the upper soil experienced extreme water shortage, but the subsoil was characterised by higher soil moisture content in the spring and early summer due to capillary water.

However, toward the end of summer, extreme water shortage was observed in the investigated profile. According to the summarised soil-water shortage based on the profile, it remained within 0—50 mm during — in the vegetation period. However, based on the — data, the water from the soil profile reached and maintained 50 mm until the end of the vegetation period, comparable to the Kelebia site.

However, comparing the two Arenosols shows higher vulnerability in Kiskundorozsma HU The difference between the soils is the humus content of the upper soil 0—10 cm , which is higher 2. Daily precipitation mm and soil-water shortage at different depths through entire investigated soil profile in Kiskundorozsma HU The differences between the two stations that are due to the irrigation at HU01 are evident in the separate duration curves for the two time periods — and — Fig.

In the rainfed Kelebia HU02 station, the order of the sensors is almost the same in drought and wet years. The topsoil generally dries earlier than the subsoil, and in drought years second time period the subsoil also shows longer water-shortage periods, thus the sensors of the upper soils and subsoils show less difference.

In the years when irrigation was applied in the case of HU01 , the normal order of the duration curves changed, and the upper sensors showed the highest AW contents.

In years without irrigation, the order of the sensors is similar for the two areas, and the lowest sensors show higher wetness for longer periods. These data assume downward water input, but the soil may get wet by capillary rise.

Also, the values near or below zero may reflect either soil frost or extreme drought. Duration curves for Kelebia HU02 and Kiskundorozsma HU01 for periods — A and C and — B and D representing non-irrigated period for both stations. Horizontal axis represents duration days when soil moisture was higher than percentage shown.

The duration and timing of high and extreme water shortage in the soil profile are important for determining drought conditions. In all other investigated years Fig. Because this dry year was compensated in the Kiskundorozsma case by irrigation, no days occurred when the whole profile was under high or extreme water shortage.

Water was missing from the whole soil profile for long periods in the cases of rainfed sandy soil, which affected all types of plants and crops. Because the longer water-shortage period in the whole soil profile was shifted to the second part of the vegetation period in , those plants that require water in spring and early summer could survive; however, the long dry period significantly affected plants or other crops.

Our results of available soil-water content for two sandy soils in southern Hungary show that of the five investigated years, four were affected by high and extreme water shortage threatening agricultural production without irrigation.

For a significant part of the vegetation period, the whole soil profile down to 75 cm became dry, which cannot easily be reversed by single rainfall events; only durable autumn and winter precipitation can replace the water without irrigation.

The study calls attention to detailed monitoring of environmental parameters and the assessment of inter-annual patterns. The countrywide drought extent and county-scale crop-yield data Table 3 highlight only the extremes of and , which tends to mask territorial vulnerability.

According to our investigations, was hit by an extreme drought, but owing to the higher AW in the soil as a result of the previous humid year, the period of high and extreme water shortage started later, thereby mitigating early spring conditions for the vegetation.

This confirms that soil moisture is an essential parameter to characterise drought conditions. In this study, total water shortage mm in the soil profile was given for both profiles, but the data are not comparable without the detailed knowledge of the soil parameters, given that they highly influence plant-water uptake.

The introduced classification of water shortage in the soil may better support agrarian water management. Because the rate and frequency of drought is predicted to increase and summer precipitation is expected to decrease in the future Bartoly et al.

As our study reflected, drought monitoring cannot be effective without monitoring of soil-moisture content. Based on this method, a new national drought-monitoring system was put in place in Hungary starting in The novelty of this system is that the applied drought index Hungarian Drought Index, HDI can distinguish between different soil types even under the same meteorological conditions Fiala et al.

Detailed analysis of AW can be used in real-time drought monitoring and can precisely indicate the evolution of drought differentiated by various soil types, which can help us manage or prevent damage from drought. The installed complex monitoring stations already exceeded in , and the provided data form the basis of daily updated drought information for the whole country ODWMS The authors confirm that the data supporting the findings of this study are available within the article or could be requested from the corresponding author, upon reasonable request.

ATIVIZIG Lower-Tisza District Water Directorate. Accessed 13 Dec Barta K, Crnojevic VB, Blanka V, Ladányi Zs, Fiala K, Vukobratovic D Possibilities of field measurement of soil moisture.

In: Blanka V, Ladányi Zs eds Drought and water management in South Hungary and Vojvodina. University of Szeged, Szeged, pp — Google Scholar. Bartholy J, Pongrácz R, Gelybó G, Szabó P Analysis of expected climate change in the Carpathian Basin using the PRUDENCE results Időjárás — Bilskie J Soil water status: content and potential.

Campbell Scientific, Inc. Accessed 12 Nov Blanka V, Mezősi G, Meyer B Changes in the drought hazard in Hungary due to climate change. Időjárás — Blanka V, Ladányi Z, Szilassi P, Sipos Gy, Rácz A, Szatmári J Public perception on hydro-climatic extremes and water management related to environmental exposure, SE Hungary.

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In: Turkan, I. Plant responses to drought and salinity stress. Developments in a Post-Genomic Era. Advances in Botanical Research — Datta S, Taghvaeian S, Stivers J Understanding soil water content and thresholds for irrigation management.

Oklahoma Cooperative Extension Service, BAE 1—8. Djordjević SV Temperature and precipitation trends in Belgrade and indicators of changing extremes for Serbia. Geographica Pannonica — Dunay S, Kalmár E A talajvízszint szerepe a talajok vízháztartásában.

Éghajlati és agrometeorológiai tanulmányok sorozat. Országos Meteorológiai Szolgálat, Budapest, pp 43— Fiala K, Blanka V, Ladányi Z, Szilassi P, Benyhe B, Dolinaj D, Pálfai I Drought severity and its effect on agricultural production in the Hungarian-Serbian cross-border area.

Fiala K, Barta K, Benyhe B, Fehérváry I, Lábdy J, Sipos Gy, Győrffy L Operatív aszály-és vízhiánykezelő monitoring rendszer. Hidrológiai Közlöny — HCSO Database of the Hungarian Central Statistical Office. Hatfield JL True Value of Carbon in Agricultural Soils. South Dakota No Till Association Annual Conference pp.

IPCC Global warming of 1. IPCC Special Report. Iglesias A, Garrote L, Flores F, Moneo M Challenges to manage the risk of water scarcity and climate change in the Mediterranean. Iglesias A, Santillán D, Garrote L On the barriers to adaption to less water under climate change: policy choices in Mediterranean Countries.

Kirkham MB Principles of soil and plant water relations. Elsevier Academic Press, Cambridge, p. Krüzselyi I, Bartholy J, Horányi A, Pieczka I, Pongrácz R, Szabó P, Szépszó G, Torma C The future climate characteristics of the Carpathian Basin based on a regional climate model mini-ensemble.

Adv Sci Res — Ley TW, Stevens RG, Topielec RR, Neibling WH Soil water monitoring and measurement. A Parcific Northwest Publication, Washington State University. Mezősi G, Blanka V, Bata T, Ladányi Zs, Kemény G, Meyer BC Assessment of future scenarios for wind erosion sensitivity changes based on ALADIN and REMO regional climate model simulation data.

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The halogen moisture analyzer performs by determining the initial weight of the sample. The internal halogen dryer heated the sample quickly until causing water content to vaporize. The drying time is shorter than a conventional oven, and once the drying procedure finishes, it automatically opens the cap, and a record of the moisture content is displayed on the screen monitor.

The sample's maximum weight in the halogen moisture analyzer is 50 g, and its weighting precision is 0. The maximum sample mass in the moisture analyzer is limited to 50 g for the halogen moisture analyzer used in this research.

For this study, the mass of the dry soil was limited to 30 g for sand and 20 g for clay. The detailed information is stored on the moisture analyzer's internal memory and can be exported to a computer for further analysis.

Tests were performed using several schemes: first, the same soil material with different water content was developed, and second, the same water content using different portions of soils. Table 1 shows definition for the specimen names.

The primary goal of this research is to compare the performance and reliability of a halogen moisture analyzer results with the results of a conventional lab oven. The results show that drying time and oven temperature have such a significant effect on the soil moisture content.

Figure 4 shows the moisture content versus time for the 10 sand specimens SCO stands for Sand specimen in the Conventional Oven. The number after SCO refers to water added to the specimen as a percentage of the dry sand mass.

As it is shown in Figure 4, the soil moisture content is reduced with time until the specimen weight remains constant. The results of the experiments demonstrate that the required time to complete the moisture content test by using the regular oven varies.

It depends on several different factors, including oven temperature, initial water content, and type of soil, assuming that the temperature of the oven is constant. Figure 5 shows that the halogen moisture analyzer dries the sand specimens completely within 32 minutes to 55 minutes depend on the specimen moisture content.

The drying time increases with the specimen moisture content. However, the required time to dry a sand specimen by using a conventional lab oven in comparison to a halogen moisture analyzer is significantly more. Table 2, Table 3 and Table 4 indicate the results of two measuring methods. The correlation coefficient indicates the closeness of fit of the halogen moisture analyzer values versus drying oven values.

It signifies that the results obtained from the conventional oven and halogen moisture analyzer have a perfect positive relationship. Similar tests were performed on the clay specimens to investigate the effect of soil type on drying time using both the conventional oven and the halogen moisture analyzer.

Figure 6 shows changes in the moisture content of the clay specimens for different initial water contents. While the total drying time for the clay specimen in the conventional oven is almost the same as for the sand specimens, the rate of losing moisture seems to be slightly slower for the clay specimens for the first 60 minutes, but the rate of losing moisture increases after an hour.

The rate of losing moisture increases with an increase in the surface area of the specimen after forming the shrinkage tensile cracks after about an hour Figure 6. Figure 7 shows the drying time for the clay specimens in the halogen moisture analyzer. Table 5, Table 6 and Table 7 indicate the results of two measuring methods.

The correlation coefficient is 0. Also, the closeness of fit of the halogen moisture analyzer values versus drying oven values is proved. Figure 8 shows the required time to dry the sand and clay specimens for a moisture content test by using the halogen moisture analyzer.

The characteristic of the clay minerals can explain the higher drying time for the clay specimens. More thermal energy or more heating time is required to overcome the forces holding the water molecules due to the negative electrical charges on the surface of clay particles and the polarity of the water molecules.

Similar results were achieved for specimens made of sand and clay. Figure 9 shows specimen moisture versus drying time for the specimens made of different percentages by dry weight of sand and clay in a conventional oven. Similar results were obtained for a mixture of sand and clay Figure 7 in the halogen moisture analyzer.

The drying time rises with increasing moisture content, and the maximum drying time for the highest moisture content is less than an hour Figure A comparison of the two methods oven-dry method and halogen moisture analyzer method to determine the soil's moisture content, along with advantages and disadvantages is presented in the following table.

The maximum amount of soil the moisture analyzer is limited to specimen holder size; this specific equipment is limited to 50 g.

therefore, for this investigation, the maximum water content that was applied was 60 percent Table 8. In this study, moisture content for soil specimens of silica sand, Kaoline clay, and mixtures of sand and clay were measured by the traditional method by using a conventional lab oven as a basis.

The moisture contents of these specimens were measured by using a halogen moisture analyzer as well, and the results of the two methods were compared.

The drying time depends on several different factors, including the moisture content of the soil, soil type, specimen size, and oven temperature. A soil specimen made of silica sand or Kaoline clay or a mixture of both should stay in a conventional lab oven for at least five hours to lose its entire pore water following the ASTM D The drying time for the same soil specimen in a halogen moisture analyzer is as low as 60 minutes or less, depends on the initial moisture content of the specimen and soil type, which is significantly less than the drying time of a conventional lab oven.

The statistics analysis result indicates that the halogen moisture analyzer provides comparable results to the drying oven method.

The specimen size of a halogen moisture analyzer, however, is small, and it is limited to the specimen holder size. Measurement of the soil moisture content using a halogen moisture analyzer is an automated process that minimizes user errors and mistakes. Besides, a halogen moisture analyzer is energy efficient as it stops the drying process once no significant changes in the specimen weight are detected.

Therefore, a halogen moisture analyzer provides a reliable and relatively fast method to determine soil water content when the number and size of specimens are relatively small.

A drying oven can estimate several samples' moisture content simultaneously. It can handle many samples and larger masses; however, the drying time is significantly more, and additional instruments, such as a precise measuring scale and sample containers, are required.

The halogen moisture analyzer is a portable automated unit suitable for measuring soil water content quickly.

Department of Mineral Engineering at New Mexico Institute of Mining and Technology provided the project funding for this research. The support of the department is acknowledged with many thanks. Arezou Rasti, Department of Mineral Engineering, New Mexico Institute of Mining and Technology, Leroy Pl, Socorro, NM, , Po Box , USA.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Figure 8: Required time to obtain soil moisture content halogen moisture analyzer-clay specimens. Figure 9: Required time to obtain soil moisture measurement by using a halogen moisture analyzer.

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Department of Mineral Engineering, New Mexico Institute of Mining and Technology, Socorro, USA. Article Abstract References PDF Assessment of Soil Moisture Content Measurement Methods: Conventional Laboratory Oven versus Halogen Moisture Analyzer Abstract Moisture content is a critical factor that affects the engineering behavior of soils, especially cohesive soils.

Keywords Moisture content, Drying oven, Halogen moisture analyzer, ASTM D Introduction A conventional laboratory oven has been strongly used for a variety of applications in the industry. Oven-dry method procedure In this study, two different processes were carried out.

The results were used as a reference for the results of the other Method halogen moisture analyzer. Halogen moisture analyzer Halogen moisture analyzers have been used to determine the moisture content of different materials.

Results and Discussion Tests were performed using several schemes: first, the same soil material with different water content was developed, and second, the same water content using different portions of soils.

Conclusions In this study, moisture content for soil specimens of silica sand, Kaoline clay, and mixtures of sand and clay were measured by the traditional method by using a conventional lab oven as a basis.

Funding Department of Mineral Engineering at New Mexico Institute of Mining and Technology provided the project funding for this research.

References ASTM Standard D Standard test methods for laboratory determination of water moisture content of soil and rock by mass. ASTM International, West Conshohocken, PA.

Cooper JD Soil water measurement: A practical handbook. Wiley Blackwell. Reynolds SG The gravimetric method of soil moisture determination part I?

J Hydrol. Visvalingam M, Tandy JD The neutron method for measuring soil moisture content - A Review. J Soil Sci Gee GW, Dodson ME Soil water content by microwave drying: A routing prodedure. Soil Sci Soc Am J Mohamed AM, Paleologos E Fundamentals of geoenvironmental engineering.

Butterworth- Heinemann. Benedetto A, Benedetto F Remote sensing of soil moisture content by GPR signal processing in the frequency domain. IEEE Sens J Dean TJ, Bell JP, Baty AJB Soil moisture measurement by an improved capacitance technique, Part I. Sensor design and performance.

J Hydrol Min L, Bing Cheng S, Wei H, et al. Ren T, Ochsner TE, Horton R, et al. Standard specification for reagent water. ASTM International. Corresponding Author Arezou Rasti, Department of Mineral Engineering, New Mexico Institute of Mining and Technology, Leroy Pl, Socorro, NM, , Po Box , USA.

Copyright © Rasti A, et al. Abstract Moisture content is a critical factor that affects the engineering behavior of soils, especially cohesive soils.

Download PDF View PDF. Views and Downloads Article views PDF downloads Figure 1: Digital photographs of the soil samples: a Silica sand and b Kaolinite. Figure 2: Oven-dry technique procedure.

Moisture analysis plays Assessnig vital clntent in Assessing water content areas of the food industry, contemt goods-in inspections, wateg Assessing water content, production, and storage to developing new products. Moisture content Macronutrient Balancing Strategies determines the Citrus aurantium for appetite suppression of materials Assessing water content often Asseszing the financial margin of finished goods. In nearly all cases, the prepared and raw ingredients have an optimum moisture content that provides the best possible recipe, taste, consistency, appearance, and shelf-life. Substances that are too dry may cause static discharge problems in production or affect the end product's consistency. On the other hand, substances that are too moist may agglomerate and clog pipes and machinery or lead to reduced shelf life. Moisture determination ensures consistent product quality.

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