Relationship Among In-Situ and Laboratory Determinations of Soil Field Capacity Under Arid Conditions

Ahmed Mohamed,Shaimaa Abd-Elrahman,Ayman Abou-Hadeed

doi:10.21608/nvjas.2021.93926.1003

Abstract

To investigate the relationship among field capacity (FC) in–situ and laboratory determinations of soil moisture content under different applied pressures of different soil textural classes, one hundred and sixty-eight of surface samples were collected. The collected samples were classified to seven groups based on the USDA texture triangle. Simulated field determinations of in-situ FC were done and the obtained results revealed that the elapsed time to reach FC and the values of soil moisture tension are different according to soil textural class. Generally, increasing water-holding pores and/or fine capillary pores, both moisture tension at FC (hfc) and elapsed time to reach it after heavy irrigation (tfc) are increased. Sand and loamy sand soils, have the highest significant correlation coefficient between in- situ FC and soil water content balanced with 60 mbar of applied pressure. While sandy loam soil achieves the highest significant value of correlation coefficient, at 100 mbar of applied pressure. The significant correlation coefficients among FC - in situ - and soil moisture content balanced with 330 mbar of applied pressure of the other soil textural classes under study are found.

Highlights

Under arid conditions, irrigated agriculture became a must
The coefficient was obtained by dividing the in-situ field capacity (FC) with a saturation point of the studied soil textured classes
Under arid conditions, irrigated agriculture is the main way of agricultural production

Summary

Introduction

Calculating available water for plant is the first step in irrigation process. Available water for plant is easy to calculate, but needs accurate estimates of both FC and permanent wilting point to be helpful in irrigation scheduling. FC is a character of the soil which usually used in soil hydraulic investigations and applications. The original definition of FC introduced by (Veihmeyer and Hendrickson 1949) and slightly modified in the (Glossary of Soil Science Terms 1984) as: “field capacity is the amount of water remaining in soil two or three days after having been wetted and after free drainage is negligible”. FC concept assumes that the water removed from the soil profile only by gravity, not through evaporation or the transpiration of plants (Hillel 2003)

Methods

Results

Conclusion