Degree Type

Thesis

Date of Award

2006

Degree Name

Master of Science

Department

Agricultural and Biosystems Engineering

First Advisor

Amy L. Kaleita

Abstract

Soil moisture is an important component of numerous systems, influencing crop development, and runoff and infiltration partitioning, among other things. However, due to its spatial and temporal variability, it is difficult to estimate soil moisture consistently using conventional techniques such as gravimetric sampling, which is point-based and time-consuming. Therefore, to overcome this drawback in soil moisture estimation and mapping, and to facilitate its measurement spatially and temporarily, remote sensing in microwave, visible, near infrared and short wave infrared is being explored and is proving to be a promising technique. But to develop models using spectral data there is a need to validate these models using ground truth data collected using gravimetric measurements and various dielectric and capacitance probes. Theta probe is one such dielectric probe, which is widely used by the remote sensing community. Not only does soil surface conditions change the response of reflectance data in various spectral ranges but has been observed to influence the measurements from Theta probe. As a part of this study an attempt has been made to understand the influence of soil temperature, roughness and crusting on Theta probe measurements by analyzing moisture content as a function of time. A nonlinear relationship was observed between the actual moisture content and Theta probe soil moisture content. A t-test conducted on the estimate of temperature concluded that the effect of temperature on Theta probe measurements was insignificant, but there is a possibility that soil surface conditions involving soil roughness and crusting could be a reason for observed nonlinearity between actual and Theta probe measurements. Therefore, future work is suggested to test the feasibility of using Theta probe under different soil surface conditions.

DOI

https://doi.org/10.31274/rtd-180813-180

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Geetika Dilawari

Language

en

Proquest ID

AAI1439890

File Format

application/pdf

File Size

49 pages

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