Water holding capacity

Several physicochemical properties of dietary fiber contribute to its physiological role. Water-holding capacity, ion-exchange capacity, solution viscosity, density, and molecular kiteractions are characteristics determined by the chemical stmcture of the component polysaccharides, thek crystallinity, and surface area. 

Water-Holding Capacity (WHC). AU polysaccharides are hydrophilic and hydrogen bond to variable amounts of water. HydratabUity is a function of the three-dimensional stmcture of the polymer (11) and is kifluenced by other components ki the solvent. Fibrous polymers and porous fiber preparations also absorb water by entrapment. The more highly crystalline fiber components are more difficult to hydrate and have less tendency to sweU. Stmctural features and other factors, including grinding, that decrease crystallinity or alter stmcture, may iacrease hydratioa capacity and solubUity. 

Vj = The actual water holding capacity of the drum between the normal water level and the level at which tubes would be critically exposed, gal. 

Vp, = The minimum water holding capacity required to replace all of the steam bubbles in the risers, gal. 

The left-hand part represents the useful fraction of water which is the difference between its input in the form of precipitations (Pr) or irrigation (Ir) and losses via evaporation (Ev) and gravitational flow (FI). In terms of Eq. (4.1), the role of hydrogels is mainly determined by their ability to increase the water-holding capacity of the soil (W) by decreasing all the losses. 

In terms of energetics, soil water is classified into several categories [134] gravitational (pF < 2), hygroscopic (pF > 4.2-4.5), and capillary (2 < pF < 4.2), where the potential is expressed as pF = lg (n, cm H20). The curves of the water-holding capacity as functions of pF(w) which are the basic hydrophysical characteristic of certain soils determine the relationship between these main kinds of water various types of these curves are available from the literature [135]. 

The previous analysis of SAH behavior in the soil clearly shows that their application for improving the water-holding capacity is not universal. Hydrogel swelling in a porous, partially salinized medium is affected by numerous factors, most often negative, and therefore a rational application of SAH demands an accurate consideration of these factors. It is evident that certain principles for adjustment of hydrogels to physical and chemical soil parameters, as well as appropriate laboratory tests and calculation algorithm systems should be worked out. 

A positive feedback between vegetation and atmospheric CO2 will occur if biomass declines. This will happen to the extent that climatic warming causes increased water stress, either through decreased precipitation or increased evap-otransporation, particularly on soils of low water-holding capacity. Decreases in soil nutrient availability, either directly caused by drought or indirectly caused by replacement with taxa with more recalcitrant litter, may further decrease the net release of carbon from the biosphere to the atmosphere. Positive feedback will also arise if the current standing biomass of trees is replaced by small trees, shrubs, and herbs that store less carbon. 

More sophisticated methods that actually measure volumetric water content can also be used, such as time domain reflectometry (TDR). In Figure 14, an example of TDR results is presented. Both the calculated and measured (i.e., TDR) volumetric water contents provide a similar picture of the profile water status by depth with time. Proper soil characterization data, such as those shown in Table 6, are necessary for these calculations and improve understanding of the test system. The determination of water-holding capacity (WHC) at 0.03 MPa field capacity (FC) and 1.5 MPa... 

Soil strength Water-holding capacity Field capacity/wilting point Hydraulic conductivity Fertility... 

Agricultural interests have amended existing soil properties to improve productivity their experience demonstrates the power of knowledge of soil properties and the ability to control them.14 A primary benefit of these amendment efforts was improvement in soil-water-holding capacity and increased rate of water removal from all soil layers by plants. The benefits of soil modification remain effective for decades. There is opportunity for similar improvements in soil during ET landfill cover design and construction. Control of ET cover soil properties has potential to enhance cover performance and should add little to construction cost. 

As shown in Figure 25.8, an increase in soil thickness from the design thickness (A) by 50% to (B) may result in only a small increase in plant-available water-holding capacity during a single... 

Base the design on reduced plant-available water-holding capacity (e.g., 10% reduction). 

The density of soil may control the presence, absence, or density of roots found in a particular soil layer. The density of plant roots in a soil layer determines how much water plants can remove from the layer and its rate of removal. Soil compaction, in addition to inhibiting root growth, reduces soil-water-holding capacity. A model that does not consider the effect of soil density on water balance may produce significant errors in water balance estimates. 

Meat quality is most affected by the length of the fattening period, meat from older animals is tighter, darker, more aromatic and has lower water-holding capacity. 

Water-holding capacity (WHC). WHC includes the ability of fresh pork to retain water and bind extra water. The higher the WHC, the more valuable the pork will be for use in highly processed products. Drip loss is an ongoing... 

The rock rose (Cistus ladanifer L.) is a typical Mediterranean plant well adapted to thin soils with low nutritional characteristics and water holding capacity as some of those found in the Iberian Pyrite Belt (IPB) (Carvalho Cardoso, 1965). This metallogenetic province is renowned by the existence of important polymetallic massive sulfide deposits and because was exploited for base metals since pre-Roman times. 

Clay soils have high water-holding capacity, and therefore will work the best for water storage reservoirs. 

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