Mohammed Salahat

Elucidation of phosphorous sorption by calcareous soils using principal component analysis

This study was conducted to understand the mechanisms governing P-sorption and desorption by calcareous soils (up to 48% CaCO 3). Batch experiments with KCl as background were carried out by adding varying amount of P up to 100 mgP.L−1. The desorption percentage (%DES) results show that little P was released from the adsorbed phase. Principal component analysis was applied to evaluate the combined influence of soil components on P sorption. The complex P sorption process can be related to specific soil components by the following equation: P− sorption=−2.20 (CaCO 3% )−0.04 (Fe− oxide)+0.04 (pHe)+11.02 (sand % )+3.35 (silt)−10.73 (clay)−1.24 (EC)−0.22 (OM)−0.81 (CEC)−1.93 (P− Olsen) (R2=0.9941, SSE=380). Sand% and clay% are the most significant variables for modelling P sorption data. The derived equation could be applied to predict P sorption in other soils that have similar compositions to those investigated herein. The degree of P saturation (DPS) threshold level for all soils was less than 3% except in the soil with the lowest iron oxide. All of the studied soils have exceeded the environmentally unacceptable P concentration except the soil with the lowest iron oxide content.

Potential of Treated Wastewater Usage for Adaptation to Climate Change: Jordan as a Success Story

Jordan sustainable development is obstructed by severe water scarcity that induces imbalances and shortages of water supply for various uses especially under high population growth rate, sudden immigrations, and climate change. Reserving water for drinking by treating wastewater treatment plants (WWTPs) effluent and reusing it for non-drinking could be a solution. This paper investigated the capability and contribution of the existing WWTPs’ effluent for reuse in agriculture sector as a climate change adaptive measure. The paper provided clear understanding for the current and future climate changes impacts, developed climate change and water policies, current water resources and demands for agriculture sector, and suggested adaptive measures. Further, it emphasized on characterizing the WWTPs and quantification of effluent taking into account the satisfaction to Jordanian standards and guidelines. Major WWTP’s effluents are within Jordanian standards; however some WWTP’s have concerns to microbial quality that restricts their reuse. Samra WWTP effluent can be used for highly restricted class of cooked vegetables, parks, and playgrounds. The results demonstrated that wastewater reuse can be a crucial part of Jordanian water budget, can solve environmental problems, and can be a feasible adaptive option when managed properly. Further recommendations for WWTP operations, managements, reuse, and monitoring are included.

Development and Evaluation of Functional Soil Mapping Unit Using Pedostructure Hierarchy Concept

Accurate soil characterization is crucial for understanding soil-water interactions and allowing for better on-farm agricultural and environmental management. Current soil characterization methods lack quantitative attributes that integrate the soil mapping units with environmental and agronomical models. In this research we proposed a methodology to physically characterize the soil water medium using quantitative parameters. We incorporated the continuously measured soil water potential curve and the soil shrinkage curve to extract the physically based pedostructural (PS) parameters needed for characterizing the soil water medium. We present a methodology to generate and define functional soil mapping units that possess physical and quantitative parameters. We followed a four step general system hierarchical approach overlaying study area map, landform map, and SSURGO map. The fourth step was to validate the generated functional soil units using discriminate analysis performed on the PS parameters extracted for every soil mapping unit. Results of this study show that surface horizon (Ap) have higher PS parameter values than subsurface horizon Bt. The PS concept showed high capabilities in defining the soil mapping units, as concluded from the discriminate analysis that was performed.

KamelSoil®: A model for soil characterization from basic soil textural properties

A new conceptual and functional model of the soil-water medium organization, in which the internal structure of the soil horizon, named the pedostructure, is made up of swelling aggregates in a hierarchy of sizes, was recently presented. This representation leads to define a new paradigm for modeling the physical interaction between the soil structure and the water at the level of the process and for the macroscopic characterization of soil physical properties at the field scale. A computer model of the hydro-structural functioning of a pedon, named Kamel®, was built in the framework of this paradigm. Accordingly, the hydrostructural input parameters of Kamel® are those of physically-based equations that describe the hydraulic functionality of the pedostructure, namely: 1) the shrinkage curve, 2) the soil water potential curve, 3) the conductivity curve, and 4) the swelling dynamic curve. These parameters have a physical meaning and can be extracted precisely from the measurement of the characteristic curves in laboratory. The objective of the paper is i) to present the basic principles of Kamel® along with the state variables and functional parameters used, allowing to calculate the state variables at each depth of the pedon and to integrate this information at the field scale level; and ii) to present “KamelSoil®”, a software that translates the traditional soil characteristics into the required hydrostructural parameters of Kamel®. Therefore Kamel® can theoretically work for all soil types, at high degree of accuracy when the characteristic curves are measured or, at least, with the same approximations made by the usual soil-water models using empirical parameters and pedotransfer functions.

Delineating Field Scale Functional Soil Mapping Units

Current soil mapping units contain qualitative parameters, which makes it difficult to integrate them with other agronomic models or decision making support systems. In this work, we propose a fresh look at soil mapping and its functionality so that it can be spatially integrated with the current field and watershed scale and water resources models. This enhancement to the soil mapping practice could be made possible by scaling up the physically-based parameters of the pedostructure or the soil-water medium characterization to the field scale following the System’s Theory Approach. The hypothesis of this research is based on the pedostructure concept, which is an approach of the hierarchical functional entities including primary particles, primary peds, soil horizon, and soil mapping units (Braudeau et al., 2004). The hypothesis behind this research is that the pedostructural parameters are independent organizational parameters that fully characterize the soil medium as determined using the continuously measured shrinkage curve and they can be exclusively used as a basis to generate functional soil mapping units. These functional units represent soil units that reflect homogenous pedostructural parameters. We will generate these functional mapping units for Haggerty-Cox property, West Lafayette, Indiana using topographic maps, existing soil survey database (SSURGO), and pedostructural parameters (PS) following the System’s Theory approach. The System’s Theory approach is a technique used to define the common area among different data layers by overlaying the layers that represent the area under study systematically starting from the largest layer and ending at the smallest entity. The resulting soil mapping unit will assist in the decision support system data analysis, which in turn will enhance and allow for the prediction of water and chemical transport and interactions.