In this video Charlotte from the SCG Education Team gives a breakdown of Sunshine Community Garden’s custom recipe for refreshing raised bed soil that has been depleted or sitting without proper protection from the Texas heat. This volunteer project by members of the Sunshine Community Gardens was at the Texas School for the Blind and Visually Impaired Garden which is also located at Sunshine. This soil refresh recipe is perfect for school or community garden beds, container gardens, or any raised beds that have been sitting unused for a period of time. Many of these tips apply to all soil amending in central Texas, even for in ground beds.
The following is Sunshines Community Garden’s custom soil refresher recipe. It does not require precision and the amounts are approximate.
6 – 10 parts spent (previous/old) old bedding mix
4 - 5 parts compost
1 part rice hulls (premoistened)
1 part shredded coconut coir (premoistened overnight if possible)
½ part kelp meal (i.e., use ½ to all of a 5lb box from Down To Earth)
½ part perlite (optional, i.e., use ½ to all of an 8-quart bag)
½ part diatomaceous earth (optional)
Add by the cup or by the handful. Use product packaging or the internet for reference:
Best added on top of refreshed soil for more immediate availability:
BREAKDOWN IN STEPS
STEP 1: On a tarp, remove old soil from beds into piles of around one-fourth cubic yard each (30-40 gallons) to make mixing easier. In the video we give a suggestion for cases when it is not possible to amend all of the old soil by inserting the compostable layer (normally at the bottom of a raised bed) above any soil that will not be amended. Amend 100% of shallow beds but 50-70% of deeper beds is fine if you have time or budget limitations.
STEP 2: Next to the pile of old bedding mix, start with a separate pile, with compost, close to the same size (20-30 gallons.) Any type of organic compost works and we chose to use turkey compost.
STEP 3: Add a significant amount of nitrogen-rich structural amendments that will break down more QUICKLY (in 1-2 seasons.) These types of organic matter are often agricultural by-products and can be free or inexpensive. Follow our recipe, product packaging or internet to determine the amount to add.
While certain amendments (like rice hulls, coconut coir or diatomaceous earth) are best pre-moistened before adding them, it is easier to mix your piles if everything is drier.
STEP 4: Add a significant amount of structural amendments that break down SLOWLY such as coco coir, peat moss, perlite and vermiculite. Follow our recipe, product packaging or internet to determine the amount to add.
STEP 5: Add minerals & silica for nutrition and cell structure. Follow our recipe, product packaging or internet to determine the amount to add.
STEP 6: Mix enriched pile of amendments until all components are uniformly distributed.
STEP 7: Combine old soil with enriched amendment pile. As you return your refreshed bedding mix to your box or containers, moisten each layer as you go so that your final result is moist enough to form a loose but distinct clump when squeezed in your hand.
STEP 8: Add cardboard on bottom of the bed or on top of left-over soil. This prevents weeds and adds more worm food.
STEP 9: Add leaves or other brown and green debris (carbon) and coffee (attracts worms) on top of cardboard. Water this layer.
STEP 10: Fill bed with half of the renewed bedding mix, followed by a watering, and then fill with remainder with another watering.
STEP 11: Top mulch the bed with any of the following types of mulch to help retain moisture. Some of these will continue to add nutrients to the soil:
MORE ORGANIC AMENDMENTS
SEAWEED OR KELP MEAL – Seaweed or Kelp Meal adds potassium (K), trace minerals, salts, alkalinizing the soil. It's an excellent bioactivator, waking the microbes in the soil to help break down organic matter.
SEAWEED SPRAY (alkalinizing) Alternatively, mix in a few handfuls of dried kelp meal. Supposedly helps with heat tolerance but cannot find a reference for that yet. NOTE: Excessive potassium or potash will decrease the soil's acidity so use it in a balanced way.)
FISH EMULSION – A fast-acting, organic liquid fertilizer made from the byproducts of the fishing industry. It is rich in nitrogen, phosphorus and potassium, plus trace elements such as calcium, magnesium, sulfur, chlorine, and sodium.
SHRIMP MEAL – nitrogen, phosphorus, calcium, and chitin
CRAB MEAL, OYSTER OR LOBSTER – nitrogen, phosphorus, calcium, and chitin
BONE MEAL – phosphorus “roots and fruits”
BLOOD MEAL – nitrogen “greening the giant”
ORGANIC N-P-K SLOW-RELEASE GRANULES – Down to Earth or Jobe’s
INSECT FRASS – Mealworm castings, cricket frass, is simply the feces of the insect.
ROCK DUST (and/or regular sand) – very slow-release minerals and SOME water retention. (Less sophisticated than Azomite, Excelerite or Green Sand)
LIME - Generally not needed in central Texas because it is too alkalinizing
AMENDMENTS THAT CAN BE CONFUSING
Biochar (alkalinizing) “potash”– If you're adding potassium to decrease the soil's acidity, use 1 to 2 pounds of hardwood ash per 100 square feet of soil. Other ways to add potassium are: add cut up banana peels and bury them 1 to 2 inches down in the soil or mix in a few handfuls of dried kelp meal or spray the soil with a liquid seaweed spray.
Coffee grounds – Brewed grounds are pH neutral but they do consume nitrogen as they decompose and compete with growing crops…but worms are mad for them. Some gardeners drop into vertical “wells” so worms can visit without significant contact with growing plant roots. ONLY UNBREWED COFFEE GROUNDS ARE ACIDIC.
More Epsom Salt for tomatoes, peppers or calcium loving plants at the time of transplant and for maintenance
Food Grade Diatomaceous Earth (FG-DE) is derived from fossilized remains of algae-like, single-cell plants called diatoms. Diatoms are some of the oldest plants in the world. They date back millions of years. These plants left behind chalky deposits called diatomite which is ground into a powder and purified for the consumer market. Chemically speaking, diatomaceous earth is 84% silica, and contains some 20 trace minerals, including small percentages of magnesium, sodium, iron and a good dose of calcium in the right ratio with magnesium for good utilization in building structures such as cell walls for healthy leaves and stems. In humans and animals, silica is essential for the building of healthy bones and teeth, skin, hair, and nails.
FG-DE is often used in the garden as a natural pest control substance. However, it can harm bees, other pollinators and ladybugs so use proper precautions as needed to reduce the chances of harm such as only using when needed for a specific pest, not over applying and avoiding use on vegetables and pollinator plants that are flowering.
Many studies have also been conducted to analyze the effect that FG-DE has as a soil amendment. These studies have shown promising results, suggesting that diatomaceous earth may significantly enhance nutrient retention and moisture retention in soil. https://www.absorbentproductsltd.com/food-grade-diatomaceous-earth-as-a-soil-amendment/
So far the conclusion is that diatomaceous earth doesn’t harm most beneficial microorganisms in the soil. Worms, for example, are not affected by the microscopic edges in diatomaceous earth particles.
WHERE TO BUY AMENDMENTS
We recommend the following local garden store for many of the amendments in our recipe. Austin Organic Gardeners, Sunshine Community Gardeners and other Austin area community gardeners are eligible to receive a discount at:
Brite Ideas Aquaponics, Hydroponics and Organics
South Austin (NEW LOCATION)
12110 Manchaca Rd. Ste. 103
Austin, TX 78748
Owner: Troy Smith
SOUTH AUSTIN STORE HOURS (CLOSED ON MONDAYS)
Tuesday-Friday 10:00 am – 6:00 pm
Saturday 10:30 am – 5:00 pm
Sunday 12:00 pm – 4:00 pm