A video demonstration of two ways to measure active carbon in orchard soils: permanganate oxidizable carbon and particulate organic matter. Authors Tianna DuPont, Andy McGuire, David Granatstein, WSU Extension. Recording from WSU virtual workshop Soil Health in Orchards with project support from the Washington State Tree Fruit Research Commission.
Text Transcript and Description of Visuals
| Audio | Visual |
|---|---|
| Organic matter includes the living, dead, and very dead material in the soil. | Title card reading “Soil Organic Matter”, shown over a close up shot of a hand holding a clump of soil |
| The active pool of organic matter is the freshest organic material, plant and animal residues that have just begun to decompose. | The hand gently moves the soil, showing it breaking apart. |
| This dynamic part of soil organic matter tends to be highly related to nutrient supply, improved soil structure, water infiltration and stimulation of microbial activity. | Close up shot of high organic matter soil, with visible earthworms and insects moving throughout. |
| It is a measure of the small portion of the organic matter that can serve as an easily available food source for soil microbes, thus helping fuel and maintain a healthy soil food web. | Close up shot of an earthworm moving through the top layer of the soil. |
| One way to measure active carbon is permanganate oxidizable carbon. This is a field demo adapting a laboratory technique. | A row of labeled clear tubes are arranged on a wooden rack. On screen text reads “Active Carbon – Permanganate Oxidizable Carbon”. |
| First you add 2 mLs of permanganate to your vials. | A pipette adds permanganate to each of the tubes. |
| Then add 18 mLs of DI water to each tube, filling to the 20 mL line. | A man wearing appropriate personal protective equipment stands in an orchard and adds water to a tube containing the permanganate |
| Then add 2.5 grams of air dried, sieved soil to each vial. | The shot returns to the tubes on the wooden rack, and soil from labeled bags is added into each tube. |
| Shake for two minutes at about 2 strokes per second. | A man stands at a table in and orchard and shakes several capped sample tubes by hand. |
| Let stand for 10 min allowing soil to settle. | The tubes are returned to the wooden rack. Text on screen reads “Let stand for 10 minutes”. |
| Add half a ml of the liquid from the upper part of the suspension to a second tube of 50 mL of distilled water. The permanganate oxidizes the active carbon and loses some of its color. | Portions of the soil suspensions are transferred via pipette to new tubes containing distilled water. |
| The more active carbon found in the soil, the more the purple color declines. This color change is measured with a spectrophotometer or colorimeter. | Three of the tubes are presented to the camera for a comparison of their color. The third tube is visibly less saturated in color than the other two tubes. |
| Here you can see that the orchard soil with more active carbon is a lighter pink color. | Three capped vials, filled with solution are displayed side by side. Labels on the screen indicate different organic matter levels and management histories, with visible differences in color saturation. |
| Another measure of active carbon is the particulate organic matter in the soil. | Twelve capped, labeled vials, filled with water and organic matter are displayed on a table within an orchard. |
| Here we have washed soil through a series of screens and removed the particulate organic matter. You can see that soils with more organic matter additions have more particulate organic matter. | On screen labels group the samples by organic matter management history. Differences in the amount of particulate matter are visible between groups |
| Organic matter additions such as compost, organic nutrients, grass clippings, wood chips are important to build the active carbon pools of our organic matter as well create as stable organic matter over time. | Two of the sample tubes are held up to the camera and shaken. Organic particles visibly swirl in one tube, while the other shows little movement. |
| End card displays “Soil Health in Orchards Workshop” with an illustration of a tree and links to additional workshop resources. |
Link to YouTube video: Organic Matter Demonstration
