IRIS TUBESIndicator of Reduction In Soils

CONCEPTSCONSTRUCTION

APPLICATIONANALYSIS

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 50-55 cm Sanded

Painted with Ferrihydrite paint

Producing Paint

Ferric chloride salt (FeCl3) 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 PaintingLower 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 ofReduction on a IRIS Tube

GROUND SURFACE

APPLICATION & TESTING IN MLRA 43AFY 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 14th to July 7th, 2006.

• Cattle are typically put out around the first of June, so exclusions are needed around each site.

TYPICAL SETTING, CLARKIA SERIESSanta Creek, Saint Maries River Watershed, Emida, ID

High Valley of St. Maries River WatershedClarkia, ID

APRIL 28TH, 2006Exclusion and Tube Setup

Check Well and Tube Close-up4-28-06

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 14th 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 1st.

• The Clarkia Series as mapped in this study area showed non- hydric conditions IN 2006. 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.

Indicators of Reduction In Soil (IRIS) Tubes

0

5

10

15

20

25

30

35

40

45

50

55

4/14/2006 4/28/2006 5/12/2006 5/26/2006 6/9/2006 6/23/2006 7/7/2006

Date

Dep

th t

o W

ater

(C

enti

met

ers)

Santa 1

Santa 2

Clarkia 1

Clarkia 2

GRAPH OF CHECK WELLS

Typical Tubes from StudyPeriod

4/14/06 – 4/28/06WT 12 cm WT – 44 CM

1-2 4-1

Typical Tubes from StudyPeriod

4/28/06 – 5/12/06 WT 44 cm WT > 50 cm

1- 4 2 - 3

COST ANALYSIS OF 4 SITESIRIS TUBES VS ELECTRONIC WATER LEVEL METERS

2-5-2007

TUBES• Fuel - 9 round trips $205.00• Supplies - 4 monitoring sites $239.94• Supplies donated by U of I ($50.00)• Wages - Monitoring Manager + Photo Analysis $2626.00• Volunteer U of I Student hours Free This Study est. $1000.00• Grad Asst. hours “ “ “ “ $100.00 • Check Wells - used old ones “ “ ” “ $20.00

Total $4240.94

METERS• W/L Meters - (4) $3180.00 • Fuel – 3 round trips $65.00• Supplies 4 monitoring sites $160.00• Wages – Monitoring Manager $864.00

Total $4269.00

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 ONIRIS 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 2005.

• Jenkinson, B.J. and Franzmeier, D.P., Development and Evaluation of Iron-Coated Tubes that Indicate Reduction in Soils, SSSAJ, 70:183-191 (2006)