Do you have a question about composting? Below are some questions about composting that we’ve received over the last couple of months. If you don’t see your question below, email it in and we’ll work on finding you an answer.
If you’re totally new to composting, make sure to check out Director Mike Maddox’s composting schedule- it may take some pressure off and reassure you that you’re going to be successful.
Mike's Composting Schedule
Mike’s Composting Schedule
Hear from Director Mike Maddox about a year in the life of his compost pile:
Only have C? Only have N?
Q:You have a large amount of a particular material to compost and don’t have the ability to balance the C:N ratio. What will happen?
A: Depending on what you have in your pile, you may see two situations result. If you have a ton of carbon in there, the pile will just likely sit there for a very long time. The pile temperature will drop and decomposition rates will slow. Will you eventually get some compost out? Probably, but it could be over years if the pile C:N ratio isn’t altered.
If you have a lot of nitrogen in there, the pile will likely start to smell. Bad. This would be a situation where you’d likely want to remedy it sooner than later by adding some carbon sources and mixing it up a bit. An easy source of carbon could be a bale of straw purchased from a garden center.
Handling challenging weather
Q: What do you do to your pile in challenging weather conditions, like if it’s really rainy for a period of time.
If it’s really rainy out, you could cover your pile with a tarp to keep additional water from entering. If it is already sodden, you’ll need to let it dry out. Excess water due to bad weather won’t hurt the pile per se, but it will slow the process down or make the situation become anaerobic. That could result in some smelly conditions, so you’ll want to turn it to add oxygen to the pile.
If it’s really dry out, you will can water it. If a handful feels like a wet, wrung out sponge, you’ve reached a good level.
Pile not warm enough?
Q: I can’t get my pile hot enough. What can I do?
Remember, piles heat up when you’re creating the correct conditions for the microbial life in your pile to decompose the materials.
-Do you have the appropriate C:N ratio? You may need to add some more N or some more C.
-Bigger piles tend to be easier to heat up than smaller piles. You can increase the size of your pile.
-You can also insulate your pile, by putting bales of straw around it to retain heat.
-If the pile is damp but isn’t warming up, you may need more nitrogen sources. Add some nitrogen-rich material. You can dig little holes in the pile to insert some more N within the pile.
-Oxygen may be needed. Turn your pile if you haven’t in awhile.
-There is a chance there could be a lack of microorganisms. Add a shovelful of finished compost or garden soil and incorporate throughout.
Pile just sitting there?
Q: I have a pile that’s been sitting there, doing nothing for a long time. What can I do to make it go faster?
Faster generally means hot composting. See the answer in the above question.
What is the optimal mix of materials?
Q: I want to make the highest quality compost possible. Is there an optimal mix of materials I could use (in addition to having a correct C:N ratio)?
Compost does contain small levels of plant nutrients and trace elements that are released over time. The greater the variety of materials used to create the compost, the greater the variety of nutrients or trace elements available in the compost. You can pay attention to the variety of materials you’re adding to your pile if you wish to optimize your end product, versus just adding one type of brown and one type of green. (Although that will produce a good compost as well.)
Can it fix my sand or clay soil?
Q: I have really sandy or really clayey soil. How much can the addition of compost “fix” my problems due to my soil type?
Amending the soil with about 1” of compost (spread out on top and then worked in to shovel blade depth) per year is a good thing in annual and vegetable beds due to the frequent disturbance of the soil. Too much may make the soil mucky and hold too much water.
Side dressing around (but not burying) perennials is good every year or so. Again, too much too fast (more than 1” on the surface) may become muck.
Can I dump all my kitchen scraps?
Q: I want to take my fruit and vegetable scraps out daily and dump them on my pile. Can I do this?
It probably depends on the amount of volume you’re talking about. If you have a large family and generate a large volume of compostable kitchen scraps, you may want to keep some carbon sources on hand to put in the pile as well. If you’re not generating a large volume of waste, this is probably less of an issue. If you end up changing the C:N ratio by adding more nitrogen sources, you will likely be able to tell by the ammonia smell your pile starts to have.
A good rule of thumb comes from Illinois State Extension: “A simple rule of thumb is to develop a volume-based recipe using from one-fourth to one-half high-nitrogen materials.”
A caution for doing this in winter: Decomposition is very slow in winter, so continual addition of food scraps could result in a soupy mess when things warm up in spring. If you want to avoid pest and odor problems as well, you need to be aware of the following for winter additions of food scraps:
-Pile must be 1 cubic yard in size (no smaller)
-You need to have enough carbon sources on hand or in the pile. You may need to keep some nearby to add in addition.
-Bury your food scraps ~8inches into the pile
-Be ready to turn things when warmer weather occurs in spring.
How and when to apply?
How much compost do we use in certain situations and when do we apply it?
When:
Best time to add compost: fall.
Second best time to add compost: spring, about a month before you’ll be planting.
Can you do it in the summer? Yes, as a top- or side-dressing is fine.
Annual beds:
Normal soil: ½-1” incorporated in.
Soil you’re working to improve (very clayey, sandy): 2-3” incorporated into the top 6” of soil
Side dressing: add ½-1” in a doughnut shape around the plant
New perennials:
You can add it directly to the planting hole or you can dig a large trench where that you fill with compost and plant into it.
Existing perennials:
Side dress these. You can add ½-1” of compost or a compost/top soil mix in a ring around the base of the perennial just like you would with mulch. Don’t try and work it into the soil as this will damage the roots.
New trees:
Don’t add compost to the hole. You don’t want to amend the soil you’re backfilling in to your hole, period. This can cause lots of problems, from creating water flow issues to causing the roots to grow in a circular pattern in the hole.
Existing trees:
You can use compost as a mulch. Apply ½-1” on bare soil approximately 2ft away from the trunk of the tree. You should apply another 2-3” of another type of mulch (ex. Wood chips) on top of the compost to keep it in place and prevent it from drying out.
Existing Lawns:
Compost can be applied as a top dressing at ~¼”. You want to make sure it is a fine layer of compost that is of fairly fine particle size (would pass through ⅜” sieve). You can apply it with a broadcast spreader or shovel it on and rake it in. In the best case scenario, you would have an aerator pass through to make holes in the turf/soil and compost could be applied and fall or be raked into the holes.
Containers:
Yes, you can use compost here. A rule of thumb: 2 parts soiless potting mix to 1 part finely screened compost (i.e. you don’t want big chunks of compost in your mix, preferably)
Do I still need to fertilize?
Q: From my understanding, compost provide micronutrients. Does this mean the plants still need macronutrients such as potassium, nitrogen and phosphorus as prescribed by a soil test?
Compost is best thought of as a way to add organic matter to the soil to improve important soil properties like structure, texture, ability to retain moisture and nutrients.
It should not be considered a fertilizer, although it contains small amounts of nutrients and trace elements that are released slowly over time.
Like you mentioned, fertilizing or amending the soil based on a soil test is the best recommendation, but adding compost to specifically address nutrient deficiencies will likely not correct them. (You also won’t know the nutrient content of the compost you’re adding.)
Too much or too little?
Q: Is there such thing as too much or too little?
Too little: It won’t hurt anything to add too little, but you may not see marked changes in soil properties compared to if you were applying it more regularly and at a higher rate.
Too much: Yes, there is such a thing as too much. Adding too much over a period of time can cause an excess of nutrients, high soluble salts and too much organic matter. Remember, you want to have OM levels no higher than 5-8% by weight.
Suggestions to keep your levels of OM at a good level but not exceeding that are:
No more than 2-3”/year for three years
Reduce to 1”/year in subsequent years
Check out this article: http://ext100.wsu.edu/gardentips/2016/08/02/too-much-compost/
