Quantification of Available Water Capacity Comparing Standard Methods and a Pedostructure Method on a Weakly Structured Soil

2019 ◽  
Vol 62 (2) ◽  
pp. 289-301
Author(s):  
Amjad T. Assi ◽  
Rabi H. Mohtar ◽  
Erik F. Braudeau ◽  
Cristine L. S. Morgan

Abstract. The purpose of this study was to evaluate the use of the pedostructure concept to determine the soil available water capacity, specifically the field capacity (FC). Pedostructure describes the soil aggregate structure and its thermodynamic interaction with water. Specifically, this work compared the calculation of soil water-holding properties based on the pedostructure concept with other standard methods for determining FC and permanent wilting point (PWP). The standard methods evaluated were the FAO texture estimate (FAO method), the Saxton-Rawls pedotransfer functions (PTFs method), and the water content at predefined soil suction (330 and 15,000 hPa) as measured with a pressure plate apparatus (PP method). Additionally, two pedostructure methods were assessed: the thermodynamic water retention curve (TWRC method) and the thermodynamic pedostructure (TPC method). Undisturbed loamy fine sand soil from a field in Millican, Texas, was analyzed at both the Ap and E horizons. The results showed that the estimated water content at FC and PWP for the three standard methods and for the TWRC method were in relative agreement. However, the TPC method used characteristic transition points in the modeled contents of different water pools in the soil aggregate and was higher for the Ap horizon, but in agreement with the other methods for the E horizon. For example, for the Ap horizon of the soil analyzed in this study, the FC estimated with the standard and TWRC methods ranged from 0.073 to 0.150 m3H2O m-3soil, while the TPC method estimate was 0.221 m3H2O m-3soil. Overall, the different methods showed good agreement in estimating the available water; however, the results also showed some variations in these estimates. It is clear that the TPC method has advantages over the other methods in considering the soil aggregate structure and modeling the soil water content within the aggregate structure. The thermodynamic nature of the TPC method enabled the use of both the soil shrinkage curve and the water retention curve in a weakly structured soil. It is expected that the TPC method would provide more comprehensive advances in understanding the soil water-holding properties of structured soils with higher clay contents. Keywords: Available water, Field capacity, Pedostructure, Pedotransfer functions, Permanent wilting point.

2021 ◽  
Vol 64 (3) ◽  
pp. 857-868
Author(s):  
Taylor C. Pinkerton ◽  
Amjad T. Assi ◽  
Valentini A. Pappa ◽  
Eunsung Kan ◽  
Rabi H. Mohtar

HighlightsQuantitative evaluation was performed of dairy waste on soil water-holding capacity.Considering the soil variability on a farm is significant for management practices.Soil aggregate structure plays a pivotal role in studying the impact of waste reuse.Abstract. The livestock sector contributes about 40% of global agricultural output and uses over 30% of total feed-crop land. The sector’s continuing growth has led to increased technology and larger-scale, commercialized agriculture, and it correlates to growth in by-products and waste, which can compromise the environment and human health. Although organic manure is an excellent soil fertilizer whose nutrient content increases crop yield, untreated and/or overapplied manure pollutes local water resources and can alter soil aggregate structure, potentially affecting soil health and available water. Proper livestock waste management is essential for sustainable food production. Waste reuse strategies exist, with goals such as minimizing freshwater consumption, improving food production, and contributing to energy production, However, each strategy has tradeoffs in environmental, energy, or monetary costs. This study provides a quantitative approach to evaluating waste impact on soil health and helps to better manage irrigation practices and water supply gaps in arid and semi-arid areas by better understanding how management practices affect physical soil health. The TypoSoil apparatus was used to measure and analyze the hydrostructural parameters (water-holding capacity and soil structure) of fine sandy loam (A horizon) and sandy clay (B horizon). Soils from the Texas A&M AgriLife Research Dairy (Stephenville, Texas) were collected and compared with control (untouched) soils. Waste (manure, bedding materials, wash water) was separated into liquid (passed through a natural lagoon treatment process) and solid components (applied as fertilizer). Approximately half the wastewater was reused as wash water, the remainder for irrigation. Although the soil varied substantially between sample locations, a statistically significant difference existed between the control and manure/wastewater applications in both the A and B horizons. Both applications improved plant-available water (AW) in the A horizon (40% and 30%, respectively) but deteriorated AW in the B horizon (25% and 30%). Thus, dairy farm waste is a viable source for agricultural use. Keywords: Available water capacity, Pedostructure, Soil health, Soil shrinkage curve, Soil water characteristic curve.


Author(s):  
André De Moura Andrade ◽  
Rui Da Silva Andrade ◽  
Erich Collicchio

Brazilian soybean has undergone considerable economic growth. Its production depends on the demand for some inputs. One of these inputs is the soil water supply, which can be made artificially or obtained by natural rainfall. Knowledge of available water capacity (AWC), which depends on total water availability (TWA), is poorly accessible and difficult to measure in the field. This study aimed to map the AWC of the state of Tocantins, based on pedotransfer functions (PTFs), to evaluate the water availability of the soils of the microregions of that state. We used the Arya and Paris model, aided by a computer program, Qualisolo, made by Embrapa Instrumentação. One hundred fifty-seven tropical soil samples were extracted from the Embrapa Solos portal. Preliminarily, the soil water retention curve (SWRC) was obtained and, subsequently, the TWA and AWC for this oilseed were estimated. Multiple linear regressions show the correlation between TWA and clay (CL), Silt (ST) and total sand (TS) contents. The correlation established was TWA = 3.2993 – 0.0028TS – 0.0034CL. This main conclusion reflects a fruitful AWC for decision-making by the soybean agribusiness and exposes the regional weaknesses for this crop under a rainfed regime in some regions of Tocantins. We could observe that, in terms of water availability, agribusiness is a potential threat to the environment protection area (APA) of the Ilha do Bananal/Cantão, Formoso River microregion.


1969 ◽  
Vol 5 (3) ◽  
pp. 167-182 ◽  
Author(s):  
J. C. Hudson

SummaryLarge soil monoliths, extracted undisturbed in 44-gallon oil drums, have been used to assess the available-water capacity, and the relation between the growth of sugarcane and soil water deficit for agricultural soils in Barbados. Constancy of field capacity was studied and the effect of cultivation on the storage of available soil water. Deep montmorillonite clays and oceanic soils had storage capacities greater than 20 cm. of water in an 80 cm. profile, whereas sandy or stony montmorillonite clays and most soils developed from kaolinite clays had capacities less than 11 cm. Cultivation significantly increased the water holding capacity of soils but this was rarely as great as for fabricated composts and the water was never so freely available. The data have been used in decisions about cultivation and irrigation, and as the basis for an ecological grouping of sugar estates according to their probable water balance.


1987 ◽  
Vol 6 (3) ◽  
pp. 109-114 ◽  
Author(s):  
P. C. Nel ◽  
J. G. Annandale

The amount of water in the soil available for plant use, as well as water use efficiency, can be largely influenced by managerial practices. Field capacity is a useful arbitrary upper limit of plant available water (PAW), but factors such as redistribution of soil water, evaporative demand and root distribution may influence it. The lower limit of PAW is often referred to as the wilting coefficient, below which soil water is unavailable to plants. Yield losses occur long before the lower limit of available water is reached. Leaf water potential, transpiration, photosynthesis and various other plant processes are drastically reduced after soil water content has reached a certain threshold level. The presence of this threshold soil water content is being questioned by some researchers. Various soil, plant and climatic factors influence PAW. Laboratory measurements of PAW have a few serious shortcomings. In situ measurements are time consuming and for this reason work is still being done on streamlining laboratory methods.


2011 ◽  
Vol 48 (No. 9) ◽  
pp. 407-412 ◽  
Author(s):  
V. Štekauerová ◽  
J. Skalová ◽  
J. Šútor

Soil hydrologic coefficients, also called hydrolimits, are soil water contents defined for certain values of water potentials. Closer attention is paid to three hydrolimits: field capacity, point of decreased availability, and wilting point. The hydrolimits can be found by various ways. Their assessment under natural conditions should be seen as laboratory assessment of hydrolimit values or use of soil water retention curves for reading of hydrolimits. Therefore, some methods for indirect assessment of the water retention curve from actually mapped soil characteristics such as soil texture, bulk density and calcium content were devised. They are generally called pedotransfer functions (PTFs). Aim of the study is to calculate values of some important hydrolimits using PTFs. The hydrolimits calculated by this way are compared to hydrolimits determined from another measured water retention curves. The presented study documents an efficiency and promptness of PTFs use for a region of interest for dynamics evaluation of water storage in the soil aeration zone considering the water supply of plants.


Land ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1290
Author(s):  
Hyunje Yang ◽  
Hyeonju Yoo ◽  
Honggeun Lim ◽  
Jaehoon Kim ◽  
Hyung Tae Choi

Soil water holding capacities (SWHCs) are among the most important factors for understanding the water cycle in forested catchments because they control available plant water that supports evapotranspiration. The direct determination of SWHCs, however, is time consuming and expensive, so many pedotransfer functions (PTFs) and digital soil mapping (DSM) models have been developed for predicting SWHCs. Thus, it is important to select the correct soil properties, topographies, and environmental features when developing a prediction model, as well as to understand the interrelationships among variables. In this study, we collected soil samples at 971 forest sites and developed PTF and DSM models for predicting three kinds of SWHCs: saturated water content (θS) and water content at pF1.8 and pF2.7 (θ1.8 and θ2.7). Important explanatory variables for SWHC prediction were selected from two variable importance analyses. Correlation matrix and sensitivity analysis based on the developed models showed that, as the matric suction changed, the soil physical and chemical properties that influence the SWHCs changed, i.e., soil structure rather than soil particle distribution at θS, coarse soil particles at θ1.8, and finer soil particle at θ2.7. In addition, organic matter had a considerable influence on all SWHCs. Among the topographic features, elevation was the most influential, and it was closely related to the geological variability of bedrock and soil properties. Aspect was highly related to vegetation, confirming that it was an important variable for DSM modeling. Information about important variables and their interrelationship can be used to strengthen PTFs and DSM models for future research.


2014 ◽  
Vol 38 (2) ◽  
pp. 464-475 ◽  
Author(s):  
Bruno Montoani Silva ◽  
Érika Andressa da Silva ◽  
Geraldo César de Oliveira ◽  
Mozart Martins Ferreira ◽  
Milson Evaldo Serafim

The plant-available water capacity of the soil is defined as the water content between field capacity and wilting point, and has wide practical application in planning the land use. In a representative profile of the Cerrado Oxisol, methods for estimating the wilting point were studied and compared, using a WP4-T psychrometer and Richards chamber for undisturbed and disturbed samples. In addition, the field capacity was estimated by the water content at 6, 10, 33 kPa and by the inflection point of the water retention curve, calculated by the van Genuchten and cubic polynomial models. We found that the field capacity moisture determined at the inflection point was higher than by the other methods, and that even at the inflection point the estimates differed, according to the model used. By the WP4-T psychrometer, the water content was significantly lower found the estimate of the permanent wilting point. We concluded that the estimation of the available water holding capacity is markedly influenced by the estimation methods, which has to be taken into consideration because of the practical importance of this parameter.


2018 ◽  
Vol 44 (2) ◽  
pp. 697 ◽  
Author(s):  
P. Pérez-Cutillas ◽  
G.G. Barberá ◽  
C. Conesa-García

This study compares two methods for the estimation of hydraulic properties of the soil at the regional scale. Soil water content (θ) values was estimated at two fixed soil matric potential values), associated with the field capacity (θfc) and wilting point (θwp). The first method is carried out directly using (θ) values of analytical determinations, by modeling them as a function of environmental variables. The second method employed texture and organic matter (OM) information to obtain (θ) values by pedotransfer functions (PTFs). The comparison of both methods allows evaluating the effect of the textures and OM, of which a significant effect of these variables is produced, suggested that there is a considerable level of consistency between the two methods, despite some differences induced by coarse textures (sand) and OM.


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