This past week my posts have been focused on soil health in the greenhouse; Organic Matter | Soil Health and No-Till | ROLS. To build on this topic I am going to introduce the method of using compost tea to improve soil health. Compost tea, though it can get technical, is simply the process of soaking compost in water to create an extract which can then be used to drench soil or as foliar feed. This technique has been around for generations and growers have been getting extremely creative with their recipes, especially the cannabis farmers. What do you think is the most important ingredient for compost tea?
You guessed it, compost! I am sure most of you are familiar with the art of composting; combining food, leaves, and all different types of decaying organic matter to create an enriched soil. This process becomes very important for creating compost tea because the quality of the tea is heavily dependent on the quality of the compost. Below is a basic compost recipe from an article on High Times:
Start with a mix that’s 25% high-nitrogen ingredients (such as manure, legumes and grass clippings from early spring), 45% green ingredients (like green plant debris, food scraps and coffee grounds), and 30% woody material (like dried leaves, wood chips and shredded newspaper). You’ll need to create a compost pile with a mass of at least one cubic yard of this combined material to ensure that, as it decomposes, the pile reaches a temperature above 135°F and stays there for three days — long enough to kill off weed seeds, pathogens and cannabis-eating nematodes.
Measure the pile with a long-stemmed thermometer that can reach its center in order to verify the temps. When the temperature reaches about 155°F, turn the pile over with a pitchfork so that the cooler outside material is now on the inside and has a chance to get hotter in its turn. Keep in mind, however, that the inside of the pile must always remain below 160°F, since that’s the point at which the beneficial microorganisms within the compost will start being killed off.
For the first week or so, expect to turn the pile every day or two, then much less frequently after that. In a few weeks, the temperature will gradually start to drop — a sign that the compost is maturing. About two months after you’ve started, the center of the pile should be cool or barely warm to the touch, which means that it’s ready to add to the garden.
Once the compost is ready to be brewed, the next step is to steep it in water for a length of time while aerating the tea. There are many ways to accomplish this mostly dependent on the size of the garden you plan to feed. Below is a video of Jim Beard from Fox Valley Technical College explaining how to make compost in a Geo Tea compost tea maker, however, the same results can be accomplished with a small air pump, a 5 gallon bucket, and some compost tea bags:
Jim states that it is key to use water that has not been treated with chlorine suggesting the use of pond water, rain water, or well water that has not been treated. He goes on to explain that the temperature of the water is best around 70 degrees so that it wont harm the biology. To start the process, you add the compost to the compost bag with the aeration tool and insert it into the water. The next step is to apply the trace nutrients of your choice, which will be the food and the micro-nutrients that will finish off the mix. For their recipe they brew the tea for around 24 to 36 hours and can dilute it 4:1 if it needs to be applied to a large crop.
Compost tea can be an effective tool to enhance your current soil routine. There is an abundance of information on the internet for different types of tea recipes and their benefits. Here is a list of a few sources:
- Cannabis plants in veg and flower
- Tons of compost tea information from Microbeman
- Different types of teas and a recipe
- Endless amounts of tea information
- Video on how to brew the tea
Compost alone is great for improving soil health, but brewing it into a tea turns all of the beneficial microorganisms into a liquid form that can be easily absorbed by plants. For this reason compost tea can supply billions of microorganisms and nutrients into the soil as well as help protect plants from pathogens, molds, and insects if used as foliar feed. It is 100% organic and has been shown to reduce or eliminate the need for chemical pesticides and fertilizers. Furthermore, it can increase retention rates for water and nutrients, break down toxins in the soil, help root systems, and save growers money while boosting both the health and yields of their plants.
Like I said in my last two posts, setting yourself up with a top of the line greenhouse is only half the battle. Considering that most greenhouse crops are often planted in pots or beds with fertilizer and bottled nutrients, the soil can lose most of its organic substance and the plants can suffer. Overall, compost tea is a cheap and effective way to improve soil and plant heath if adopted into your existing soil routine.
Do you have any experience with this topic? What is your favorite compost tea recipe? Please leave your thoughts in the comment section below.