Remote Sensing of Subsurface Soil Moisture

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2015-GARR-67184
In agriculture, being able to appropriately measure soil moisture would be advantageous towards crop yields and efficiency of irrigation. Water for irrigation is becoming very scarce in certain locations, such as California, so being able to tailor irrigation is necessary. Plants absorb water through their roots, having an accurate assessment includes knowledge of the distribution of water from the soil surface all the way to the roots, called root zone soil moisture. Currently, in situ methods require the insertion of a probe into soil, or the collection of a sample at the location where the measurement is made. Although this is precise, it is limited to a single point or location, water distribution is uneven across a field. Deployment of in situ sensors at a density necessary to map this variation is not feasible due to the cost of such large number of sensors, their maintenance, and the communication infrastructure to extract data from them, collectively. Therefore, there is a need to be able to measure this zone of moisture for agricultural purposes in a more efficient manner.

Researchers at Purdue University have developed an instrument/software that allows remote sensing of subsurface soil moisture from an airborne instrument using reflective electromagnetic radiation. This can provide the most efficient method to collect measurements and survey an entire field with high spatial density in a short period of time. It makes use of lower-frequency signals, which are required to penetrate the soil. Resolution is determined only by the frequency of the signal, under the assumption of a near-specular reflection, not the antenna size. These features will allow use of this instrument on small airborne platforms, such as UAVs, and airborne measurements provide much higher resolution and more targeted measurements than satellites. Hence, this technology would provide a modern approach to agriculture and improving irrigation efficiency.

Advantages:
-Remote sensing of moisture
-Surveys a large field area
-Allows airborne measurements

Potential Applications:
-Precision agriculture industry
-UAV industry

Related Publications:
James Garrison, et al. Remote sensing of soil moisture using P-band signals of opportunity (SOOP): Initial Results. IGARSS 2017, July 23-28, 2017, Fort Worth, Texas.

James Garrison, et al. Recent Results on Soil Moisture Remote Sensing Using P-band Signals of Opportunity.
May 10, 2017
Utility Patent
United States
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May 10, 2016
Provisional-Patent
United States
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May 10, 2015
Provisional-Patent
United States
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