Date of Award:

12-2008

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Committee Chair(s)

V. Philip Rasmussen

Committee

V. Philip Rasmussen

Committee

Ralph E. Whitesides

Committee

Grant E. Cardon

Abstract

Subsoil compaction is a major yield limiting factor for most agricultural crops. Tillage is the most efficient method to quickly treat compacted subsoil, but it is also expensive, increases erosion, and accelerates nutrient cycling.

The use of real-time electrical conductivity (EC) and near-infrared (NIR) reflectance values to differentiate compacted areas from uncompacted areas was studied. This method has potential to reduce monetary and time investments inherent in traditional grid sampling and the resultant deep tillage of an entire field. EC and NIR reflectance are both very sensitive to spatial variability of soil attributes.

The objective of this research was to determine whether the amount of soil moisture affects the efficacy of EC and NIR spectroscopy (at 2151.9 nm) in identifying subsoil compaction through correlation analysis, and also to determine whether a minimum level of compaction was necessary for these same methods to detect compaction in three different soil textures across a variable water gradient.

Bulk density measurements were taken in late 2007 from plots traversing an induced soil moisture gradient, and low, medium, and high levels of compaction at three locations with different soil textures. A Veris Technologies (Salina, KS) Near-Infrared Spectrophotometer equipped with an Electrical Conductivity Surveyor 3150 was used to measure and geo-reference EC and NIR reflectance data over the same plots. Analysis of the data for a correlation between compaction (bulk density values) and EC, as well as compaction and NIR reflectance, produced clear results.

It was found that electrical conductivity is not significantly different between compacted or uncompacted soils even when tested at all moisture extremes and in different soil textures in Utah. Also, NIR spectroscopy was unsuccessful at identifying subsoil compaction because all tested procedures to induce a spectrometer into the soil resulted in changes the physical properties of the soil.

Checksum

7f87e5a4715a08bcf9e3b8a2ddaafff2

Download

Included in

Soil Science Commons

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .