Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Agricultural and Biosystems Engineering

First Advisor

Stuart J. Birrell


An Automated Electro-Pneumatic Soil Sampling (EP) method based on pressurized air for real time soil analysis was developed and tested in laboratory conditions. Pressurized air was applied for 36 milliseconds across a 3 cm diameter cylinder to cut a soil column and convey soil along a delivery pipe into a container. An electro-pneumatic regulator valve was used to regulate the air pressure at 550, 690, and 830 kPa using an analog electrical signal. A two-position solenoid valve controlled by a stand-alone microprocessor was used to control pulse duration. The effects of air pressure level, soil moisture content, soil compaction, and soil type on the quantity of soil sample obtained were investigated. Moisture content and pressure level were found to be the most significant factors, while compaction was not significant in terms of mass of soil obtained. Laboratory test results showed that pressurized air was effective in cutting and transporting soil sample for all different soils and different soil conditions studied in the experiment. The electro-pneumatic method was also capable of obtaining a consistent amount of soil sample in a short time period (36 ms) with a coefficient of variation of less than 30%.;A shank as soil sampling arm was designed and constructed. The EP system was integrated with the prototype of soil sampling shank to develop a complete Real-Time Electro Pneumatic Soil Sampling System (REPS). The performance of the REPS system was tested during preliminary field tests, and performance was evaluated in a soil bin. The effects of traveling speed, soil moisture content, and pulse duration and pressure level on the amount of soil sample collected were investigated. All the factors in the experimental design were found to be highly significant (alpha=0.05) on the amount of soil sample obtained. The amount of sample were predicted with a high correlation coefficient (R2=86) for all different soil moisture content. The REPS could be a strong candidate for real-time soil sensing system.



Digital Repository @ Iowa State University,

Copyright Owner

Saadettin Yildirim



Proquest ID


File Format


File Size

94 pages