IRIS TUBES I ndicator of R eduction I n S oils CONCEPTS CONSTRUCTION APPLICATION ANALYSIS

CONCEPTS Develop alternative to quickly determine if reducing conditions are present Hopefully less expensive Accurate Widely adaptable

IRIS Tube Construction PVC tubes are cut into approximately 60 cm lengths Tubes are cleaned with acetone Lower cm Sanded Painted with Ferrihydrite paint

Producing Paint Ferric chloride salt (FeCl 3 ) added to distilled water PH is raised with KOH to precipitate the oxide Salts are removed Solution evaporated to the consistency of oil based paint

IRIS Tube Painting Lower 55 cm of the tube is sanded

One coat of paint is applied to the lower 55 cm.

FIELD & PHOTOGRAPHIC PROCEDURE Tubes are inserted into the soil by first making a hole with a push probe They are replaced every two weeks straddling the start of growing season When removed from site the tubes are ID’d, rinsed off, dried and photographed at 120 degree turns. The photography for all tubes can be done at once, later If 20% of the Ferrihydrite paint is reduced one can conclude that the soil is reducing (87% confidence, hydric soil tech std.) If 30% is reduced then one can be confident the soil is reducing

Example of Reduction on a IRIS Tube GROUND SURFACE

APPLICATION & TESTING IN MLRA 43A FY 2006 The Clarkia Series currently an Endoaqualf in Benewah and Shoshone Counties has been mapped on floodplains, valley floors and stream terraces. The problem is descriptions have redoxamorphic features and/or reduced colors straddling the SWP/PD interface. Particularly on the terraces. Tubes were set within the Map Units in pastured summer range from April 14 th to July 7 th, Cattle are typically put out around the first of June, so exclusions are needed around each site.

TYPICAL SETTING, CLARKIA SERIES Santa Creek, Saint Maries River Watershed, Emida, ID

High Valley of St. Maries River Watershed Clarkia, ID

APRIL 28 TH, 2006 Exclusion and Tube Setup

Check Well and Tube Close-up

EXPECTED RESULTS A defined drainage class and/or revised classification for the Clarkia series Proper Map Unit design for Benewah County Soil Survey ( finishing in spring of 2008) Enhance the future maintenance of the St. Joe - Shoshone Survey Area Testing of the IRIS tube procedure without the support of (Pt) electrodes, electronic piesometers, etc.

IRIS TUBE ANALYSIS, 2006 STUDY The Tubes worked as designed! When the Water & Temperature were present, the tubes showed reduction. Sites 1 – 3 were saturated to the surface on April 14 th and during the ensuing 14 days water tables dropped and temperatures climbed. Only Site #1 had both reducing and hydrology indicators carrying into the growing season. Extrapolated rainfall data for the period in the Saint Maries watershed indicated about a 4% drop in Average Precipitation but considering strong spring runoff this was probably insignificant. Drainages near by stayed near top of banks until ~ May 1 st. The Clarkia Series as mapped in this study area showed non- hydric conditions IN Neither Hydrology or reduction indicate hydric conditions during growing season in a majority of studied area. Depressions and drainage ways are most likely hydric and these could be considered inclusions in a redesigned map unit. Additional Note: Once the WT had dropped it did not rebound after a significant rain at three of the sites even site 3 where a perennial stream ran on the surface 50’ away rebound was minimal.

GRAPH OF CHECK WELLS

Typical Tubes from Study Period 4/14/06 – 4/28/06 WT 12 cm WT – 44 CM

Typical Tubes from Study Period 4/28/06 – 5/12/06 WT 44 cm WT > 50 cm

COST ANALYSIS OF 4 SITES IRIS TUBES VS ELECTRONIC WATER LEVEL METERS TUBES Fuel - 9 round trips $ Supplies - 4 monitoring sites $ Supplies donated by U of I ($50.00) Wages - Monitoring Manager + Photo Analysis $ Volunteer U of I Student hours Free This Study est. $ Grad Asst. hours“ “ “ “ $ Check Wells - used old ones“ “ ” “ $20.00 Total $ METERS W/L Meters - (4) $ Fuel – 3 round trips $65.00 Supplies 4 monitoring sites $ Wages – Monitoring Manager $ Total $

ANALYSIS CONTINUED 4 Sets of Iris tubes Vs 4 WL-16 Loggers ~ Same Cost over 12 week monitoring period. Although when monitoring over 4 Sites the costs begin to favor IRIS -TUBES one must also consider the amount, accuracy and kind of data. The Electronic Water Loggers give you real time WT data up to 48 times a day year round. If you only need 1 or 2 readings a day (Saves Battery Life) then you only need to download semi-annually. Downloading can be done in a few minutes, anytime. Conclusions - When applying to Soil Survey Inventory Work The time savings in using the Electronic Loggers would be substantial. In this example project management takes ~ 2/3 less time. If NRCS also built the tubes, made the paint, etc., the savings would be ~ 4/5. SO, unless setting out a large array of sampling sites or you specifically need to know reduction is occurring, the Electronic Water Table Loggers will be cheaper and supply more information.

SOURCES OF ADDITIONAL INFORMATION ON IRIS TUBES Jenkinson, B.J., 2002, Hydrology of sandy soils in northwest Indiana and iron oxide indicators to identify hydric soils. Ph.D. thesis. Purdue Univ., W. Lafayette, IN. Rabenhorst, M.C. and Castenson, K.L., Temperature Effects On Iron Reduction In A Hydric Soil, Soil Science, Vol. 170, No. 9, September Jenkinson, B.J. and Franzmeier, D.P., Development and Evaluation of Iron-Coated Tubes that Indicate Reduction in Soils, SSSAJ, 70: (2006)