As the weather starts to turn cooler and fall approaches, I turn my attention to the compost. This is clearly because I have a little more time available, after the rush of harvest and canning is winding down. But, fall is a great time to focus on compost because it makes sense to have a great batch ready for springtime planting and bed amending.
What is Compost Tea?
Compost tea is the water runoff after you have seeped your fully composted or mostly composted (finished) material. Nutrients from the compostables leach into the water creating a highly potent cocktail for plants. The nutrients in the liquid are theoretically more quickly absorbed into the plant’s cells than regular compost.
But, why not just use the compost? When and why should I go through the trouble of making the tea?
Why Compost Tea
Compost tea has some very vocal proponents. Scientific research supporting many of these claims is thin. However, while certain claims about its usage should be taken with a grain of salt, there is clear evidence that compost tea contains many of the same beneficial nutrients which help plant growth, and that it does increase the population of mycorrhizal fungi and predatory nematodes.
Compost tea has a few fantastic uses, but not all uses for this concoction are equal. For example, you should never expect to improve your soil with compost tea. The nutrients in the tea are dilute and will likely dissipate / evaporate prior to doing any good for the soil. Instead, use your regular compost and mix it in well to the existing soil to improve it. Regular compost not only increases the nutrition and the microorganisms, but also better aerates the soil.
However, where compost tea does shine, is when you need a quick plant “pick-me-up” for a plant in distress; especially a quick growing vegetable or annual flower. It is also great for plants showing stress from prolonged drought. Where compost or fertilizer applied directly to the base of a plant show results in approximately 24 – 48 hours, compost tea could show a perkier plant in as little as a few hours.
Also, making tea is a great option if you have compost which has gone bad or failed to fully decompose. This happens if the pile is too dry, too wet, or just not hot enough. The compost often starts to break down, but then slows or stops as the conditions become unfavorable – often in the heat of summer or the wet of winter.
Some people will take this partially broken down material and trench compost it. This is a great option. But if you have limited space, or if digging is difficult due to the possibility of damaging roots with digging or burning, compost tea is your solution.
Compost tea is not a magic bullet, but it is a useful weapon to have in your arsenal in your war toward healthy plants and great soil quality, alongside bin composting and trench composting.
Types of Compost Tea
Compost tea can either be aerated, non-aerated, or a combination of the two. Aeration is just the process of applying oxygen to the matter. In the absence of oxygen, the anaerobic process will prevail.
Traditionally, live or non-composted plant material was most often used to make what we now think of as compost tea. The matter was steeped and stirred in water until it smelled foul, and then it was applied to crops. As crop management became more scientific with the rise of the industrial revolution, growers gained a greater understanding of the nutritional needs of plants. And the concept of water solubility. Now we know that compost tea should always be made with finished compost.
In addition to aerated and non-aerated, there are also some other variations. For example, worm farm tea from vermiculture leachate is an excellent plant fertilizer (vermicompost tea). Rabbit manure tea and chicken manure teas are other types of popular compost teas. Just be careful that whatever you use to steep in water has been sitting around for more than a few days. Otherwise it will get smelly and not efficiently transfer the nutrients to the tea (solubility). Using ‘raw’ or un-rotted material in compost tea is not advisable and has very little soluble nutrients. (And by the way, mixing fresh banana peals in water does not help your plants).
Compost Gone Bad
Sometimes when you make compost in a bin, there is not enough water and you get super dry clumps. These clumps are basically areas in the compost pile that superheated and started to decompose. However, at some point the heat dried up all the water and the compost dried out into hard clumps. SUPER hard clumps. Impossible to use in your soil.
Your best bet if you get super dry compost clumps is to make compost tea. Take the rock hard clumps, put them into a tub and fill the tub with water. The compost will absorb all of the water and still probably be too dry to use. You’l likely need to fill the tub a second time until the clumps soften enough that you can break them down into soil with your hands.
After the compost has steeped in the water for 2-3 days, you can not only use the tea on your plants, but you can also amend your soil with the strained compost ‘soil’. Depending upon how composted the matter was prior to the steeping, you may choose to trench compost the leftover matter.
While science still can’t explain some of the observed empirical evidence related to benefits of compost tea, there is consensus that it does indeed improve microbial activity. And while this may not necessarily translate to greater soil productivity, it does indeed support a healthier plant and an overall healthier ecosystem.
