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Water Capacity (water + capacity)

Distribution by Scientific Domains

Earth and Environmental Science	50%

Selected Abstracts

Online Particle Size Measurement in Microgel Particle Suspensions: Principles and Data Analysis

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 10 2010
Prof. Dr.-Ing.
Abstract If a gelled system is subjected to shearing or the concentration of reactive components is low, microgel particles are formed. Since labile microgel particles with high water capacities can often be found in food systems, and as they are important for the textural properties, particle size measurement is relevant for fundamental research and control of industrial processes. A chord length measurement system was tested for online particle sizing. [source]

Organic carbon additions: effects on soil bio-physical and physico-chemical properties

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2009
A. Bhogal
Summary The effects of organic carbon (OC) additions from farm manures and crop residues on selected soil bio-physical and physico-chemical properties were measured at seven experimental sites, on contrasting soil types, with a history of repeated applications of farm manure or differential rates of inorganic fertilizer nitrogen (N). Repeated (> 7 years annual additions) and relatively large OC inputs (up to 65 t OC ha,1) were needed to produce measurable changes in soil properties, particularly physical properties. However, over all the study sites, there was a positive relationship between OC inputs and changes in total soil OC and ,light' fraction OC (LFOC), with LFOC providing a more sensitive indicator of changes in soil organic matter status. Total soil OC increased by an average of 3% for every 10 t ha,1 manure OC applied, whereas LFOC increased by c. 14%. The measured soil OC increases were equivalent to c. 23% of the manure OC applied (up to 65 t OC ha,1 applied over 9 years) and c. 22% of the crop residue OC applied (up to 32 t OC ha,1 over 23 years). The manure OC inputs (but not crop residue OC inputs) increased topsoil porosity and plant available water capacity, and decreased bulk density by 0.6%, 2.5% and 0.5% with every 10 t ha,1 manure OC applied, respectively. Both OC sources increased the size of the microbial biomass (11% increase in biomass C with 10 t OC ha,1 input), but only manure OC increased its activity (16% increase in the soil respiration rate with 10 t OC ha,1 input). Likewise, the potentially mineralizable N pool only increased with manure N inputs (14% increase with 1 t manure total N ha,1). However, these soil quality benefits need to be balanced with any potential environmental impacts, such as excessive nutrient accumulation, increased nitrate leaching and phosphorus losses and gaseous emissions to the atmosphere. [source]

Late prehistoric soil fertility, irrigation management, and agricultural production in northwest coastal Peru

GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2004
Lee Nordt
The Pampa de Chaparrí (Pampa) in hyperarid northwest coastal Peru is an ideal area to study late prehispanic agricultural technology and production because irrigation canals and furrowed fields have been preserved since abandonment approximately 500 years ago. We collected 55 samples for soil characterization, fertility, and micromorphic analyses and compared these results to a noncultivated control soil previously sampled in an adjacent valley. Natural soil fertility levels for maize, cotton, and bean production were generally high during late prehispanic cultivation in the Pampa. Maintaining adequate nitrogren levels for production, however, would have required external inputs from livestock manure, guano, or leguminous plants. The management of low soil salinity levels was possible because of rapidly permeable soils and irrigation waters low in salt. Based on available water capacity and climate conditions, the Blaney-Criddle Equation yields evapotranspiration rates indicating that irrigation frequency was necessary in a range of every 10,16 days during the growing season. © 2004 Wiley Periodicals, Inc. [source]

Simulating daily soil water under foothills fescue grazing with the soil and water assessment tool model (Alberta, Canada)

HYDROLOGICAL PROCESSES, Issue 15 2004
Emmanuel Mapfumo
Abstract Grazing is common in the foothills fescue grasslands and may influence the seasonal soil-water patterns, which in turn determine range productivity. Hydrological modelling using the soil and water assessment tool (SWAT) is becoming widely adopted throughout North America especially for simulation of stream flow and runoff in small and large basins. Although applications of the SWAT model have been wide, little attention has been paid to the model's ability to simulate soil-water patterns in small watersheds. Thus a daily profile of soil water was simulated with SWAT using data collected from the Stavely Range Sub-station in the foothills of south-western Alberta, Canada. Three small watersheds were established using a combination of natural and artificial barriers in 1996,97. The watersheds were subjected to no grazing (control), heavy grazing (2·4 animal unit months (AUM) per hectare) or very heavy grazing (4·8 AUM ha,1). Soil-water measurements were conducted at four slope positions within each watershed (upper, middle, lower and 5 m close to the collector drain), every 2 weeks annually from 1998 to 2000 using a downhole CPN 503 neutron moisture meter. Calibration of the model was conducted using 1998 soil-water data and resulted in Nash,Sutcliffe coefficient (EF or R2) and regression coefficient of determination (r2) values of 0·77 and 0·85, respectively. Model graphical and statistical evaluation was conducted using the soil-water data collected in 1999 and 2000. During the evaluation period, soil water was simulated reasonably with an overall EF of 0·70, r2 of 0·72 and a root mean square error (RMSE) of 18·01. The model had a general tendency to overpredict soil water under relatively dry soil conditions, but to underpredict soil water under wet conditions. Sensitivity analysis indicated that absolute relative sensitivity indices of input parameters in soil-water simulation were in the following order; available water capacity > bulk density > runoff curve number > fraction of field capacity (FFCB) > saturated hydraulic conductivity. Thus these data were critical inputs to ensure reasonable simulation of soil-water patterns. Overall, the model performed satisfactorily in simulating soil-water patterns in all three watersheds with a daily time-step and indicates a great potential for monitoring soil-water resources in small watersheds. Copyright © 2004 John Wiley & Sons, Ltd. [source]