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United States Department of Agriculture

Agricultural Research Service

Title: Neutron Moisture Meter Calibration in Soils of Uzbekistan

Authors
item Kamilov, Bakhtiyor - UZBEKISTAN NATL. COTTON
item Evett, Steven
item Ibragimov, Nazirbay - UZBEKISTAN NATL. COTTON

Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 4, 2004
Publication Date: October 5, 2004
Citation: Kamilov, B., Evett, S.R., Ibragimov, N. Neutron moisture meter calibration in soils of Uzbekistan [abstract]. Agronomy Abstracts, ASA-CSSA-SSSA Annual Meeting, Seattle, Washington. 2004 CDROM.

Technical Abstract: An important key thrust of our investigations was measurement of soil profile water content. For this purpose, we used the soil moisture neutron probes (SMNP). The SMNP were calibrated for each soil condition at five locations in Uzbekistan, in soils ranging from silt loam, uniform in texture and derived from loess in Tashkent, to highly stratified alluvial soil in Khorezm. All calibrations involved creating a wet site containing at least two access tubes in a field that was otherwise as dry as possible. Two access tubes were also installed in the dry plot, preparation of which was done by crop and field management over the preceding year. Reasonable precise calibration equations were obtained for all soils. The root mean squared error of regression ranged from 0.0085 to 0.025 m3/m-3. Also, due to nearness to the surface, equations for the 10 cm soil depth in Tashkent, Syrdarya and Kashkadarya were different in slope from equations for deeper layer. Distinctly different soil horizons were identified. In Khorezm, an abrupt change in the soil texture near 70-cm depth caused separate calibration equations for the 30 to 70-cm depth range (silt loam) and the 110 to 170-cm depth range (fine sand). Calibration in Fergana was successful for the 10 cm and the 30 to 90-cm depth range.

Last Modified: 7/25/2014
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