SPATIAL VARIABILITY OF HYDRO-RELATED PHYSICAL PROPERTIES OF AL-RASHEED LOAM

Tareq K Masood,Salloom B Salim

doi:10.36103/ijas.v53i1.1521

Abstract

A field study was conducted on 2 hectare area at Al- Rashid district, south of Baghdad to analyze the spatial variability of saturated hydraulic conductivity (Ks), initial infiltration rate (IR), Porosity (F) and bulk density (BD). Based on measured BD values Rosetta software was used in this study to estimate water retention parameters, water content at θ33 and θ1500 kPa and unsaturated hydraulic conductivity at 33 kPa(k33), 100 kPa(k100) and 1500 kPa(k1500) according to Van Genuchten-Mualem model. Measured and predicted data were analyzed both statistically and geostatistically and, the results showed a strong to moderate spatial dependence for the studied characteristics. The spatial correlation values (r2) were obtained with a spherical model for Ks, θ33, θ1500, k33, k100 and k1500, an exponential model for IR, and a Gaussian model for F and BD. Ks increased significantly with increasing of IR (r2 = 0.49**) and decreased with increasing of F and BD, IR increased with decreasing of BD (r2 = -0.326*) and BD increased with increasing of F (r2 = 0.989 **). In general the spatial distribution was moderately skewed (-0.5 to 0.5) for the studied characteristics with pronounced kurtosis (>2.5). The limit distance for the search radius to estimating spatial dependency varied from 29.9 m for BD to 105 m for IR.

Highlights

There is a lack of information and knowledge about soil variability, which necessitates more research because variations in soil properties must be controlled to allow for better soil and crop management [16, 3]
Understanding the spatial variation of soil properties is critical for crop production in agricultural management systems and is regarded as a cornerstone of site-specific agriculture especially most soil properties are spatially variable, and that this variance is normal and attributable to geological and biological soil formation factors [14].Some physical properties of various soils, such as saturated and unsaturated hydraulic conductivities, have been discovered to have a lot of statistical variance [5,29].The occurrence of changes in soil structure, bulk density, soil porosity and water characteristics in space and time is mostly due to spatial variability in some practices in the field [23,30]
The bulk density was estimated by the core method [6], Ks values were assumed to be equal to final IR, IR was measured with double ring infiltrometer. θ33, θ1500, k33, k100and k1500 were estimated with Rosetta software

Summary

Introduction

There is a lack of information and knowledge about soil variability, which necessitates more research because variations in soil properties must be controlled to allow for better soil and crop management [16, 3]. Understanding the spatial variation of soil properties is critical for crop production in agricultural management systems and is regarded as a cornerstone of site-specific agriculture especially most soil properties are spatially variable, and that this variance is normal and attributable to geological and biological soil formation factors [14].Some physical properties of various soils, such as saturated and unsaturated hydraulic conductivities, have been discovered to have a lot of statistical variance [5,29].The occurrence of changes in soil structure, bulk density, soil porosity and water characteristics (infiltration rate and saturated hydraulic conduction) in space and time is mostly due to spatial variability in some practices in the field [23,30]. Soil water content and unsaturated hydraulic conductivity measurements are both costly and time-consuming. To estimate those in terms of readily available soil properties, pedotransfer functions (PTFs) have been developed [1]. The aim of this study is to determine the spatial variability of Ks, IR, F, BD, θ33, θ1500, k33, k100 and k1500 along 100 m × 200 m coordinates at Al-Rasheed district, south of Baghdad

Objectives

Methods

Results

Conclusion