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Resin Strip Preparation & Extraction.md

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Soil Nutrient Availability via Resin Strips Phosphate (PO4-3 ), Nitrate (NO3- ), and Ammonium (NH4+)

Modified by Stephanie Kivlin – 05.22.2018

Rationale

Resin strips are charged membranes that simulate a root surface. These strips can either be charged to attract negatively charged plant-available nutrients (Anion Resins) or positively charged plant-available nutrients (Cation Resins). Resins can be purchased from Membranes International. (https://www.membranesinternational.com/tech- ami.htm).

Materials

Anion and cation resin paper cut into 2 x 10cm strips, punched with a hole punch with a string and metal tag attached

0.5M Sodium Bicarbonate (NaHCO3 ) 0.5M Sodium chloride (NaCl) 0.5M Hydrochloric acid (HCl) 2.0M Potassium chloride (KCl) 18 ohm water from the Millipure filtration system acid washed glassware/carboys shaker

Resin strip preparation

  1. Make 0.5M NaHCO3 by adding 126.015g of NaHCO3 to 3L of Millipore water in a large acid-washed flask. You may need to make multiple batches, and can reuse the flask to do so.

  2. Convert the anion resin to the bicarbonate form by shaking resin strips for 10 min in each of three successive baths of 0.5M NaHCO 3 . Typically, for ~50 strips you can use 1L per bath. For ~200 strips, use 3L per bath. Choose an amount and a container that will allow the strips to be covered with solution, but not spill over on the shaker. Rinse resin strips with Millipore water between each equilibration by adding the strips to a clean, acid-washed plastic bin filled with water for 5 min.

  3. Convert the cation resin to the active form by shaking resin strips for 10 min in each of three successive baths of 5% NaCl. Make 5% NaCl by adding 17.52g of NaCl to 3L of Millipore water in a large acid- washed flask. You may need to make multiple batches, and can reuse the flask to do so. Convert the cation resin to the charged form by shaking resin strips for 10 min in each of three successive baths of 0.5M NaCl. Typically, for ~50 strips you can use 1L per bath. For ~200 strips, use 3L per bath. Choose an amount and a container that will allow the strips to be covered with solution, but not spill over on the shaker. Rinse resin strips with Millipore water between each equilibration by adding the strips to a clean, acid-washed plastic bin filled with water for 5 min.

  4. After the last equilibration and rinse, resin strips can be stored in Millipore water in the refrigerator for several months. Store anion and cation strips separately.

Fieldwork

  1. Using a soil knife create a ~12 cm deep vertical slit in the soil for each resin strip. This will be a total of three strips per replicate (one anion for PO4-3 , one anion for NO3- , and one cation for NH4+)

  2. Place the resin strip with the string and tag end on top into the slit.

  3. Make sure that soil is touching all sides of the resin.

  4. After ~1 month remove the strip and place into a pre-labeled whirlpak or ziplok bag with ~5ml of Millipore water. Duration of incubation in the field will vary among ecosystems.

Resin Strip Phosphate Extraction

  1. Make 0.5M HCl by adding 42 ml of 12N HCl to 1L of Millipore water in an acid- washed flask. Wear safety gear and add the acid slowly to the water in the fume hood to avoid a strong exothermic reaction.

  2. Place each resin strip in a 4 oz cup with 100 ml of 0.5M HCl and shake for 1 hour. CO2 will outgas during this step, so make sure to shake the cups inside a plastic bin to catch any spillover. If you get any HCl solution on the shaker, clean it up immediately to avoid damage to the shaker.

Resin Strip Nitrate Extraction

  1. Make 2.0M KCl by adding 149.10 g of KCl 1L of Millipore water in an acid-washed flask. Wear safety gear and add the acid slowly to the water in the fume hood to avoid a strong exothermic reaction.

  2. Place each resin strip in a 4 oz cup with 100 ml of 2.0M KCl and shake for 1 hour. Make sure to shake the cups inside a plastic bin to catch any spillover. If you get any KCl solution on the shaker, clean it up immediately to avoid damage to the shaker.

Resin Strip Ammonium Extraction

  1. Make 2.0M KCl by adding 149.10 g of KCl 1L of Millipore water in an acid-washed flask. Wear safety gear and add the acid slowly to the water in the fume hood to avoid a strong exothermic reaction.

  2. Place each resin strip in a 4 oz cup with 100 ml of 2.0M KCl and shake for 1 hour. Make sure to shake the cups inside a plastic bin to catch any spillover. If you get any KCl solution on the shaker, clean it up immediately to avoid damage to the shaker.

References Robertson et al., 1999. Standard Soil Methods for Long-Term Ecological Research (117- 120).

Modified from protocol by CV Hawkes