Blog

QUESTION: How long does a compost pile stay hot?

ANSWER: A properly maintained compost pile will heat up after turning, reaching temperatures of at least 130 degrees F, and maintaining similarly high temperatures for two to four days before declining.

Once the temperature of the pile reaches about 100 degrees F, turn the pile again, and temperatures will again rise to 130 degrees F or higher as the organic materials in the pile break down. A properly maintained compost pile generally reaches temperatures between 120 and 170 degrees F when breaking down organic matter.

QUESTION: How long do eggshells take to compost?

ANSWER: Eggshells typically take a remarkably long time to compost, and though they supposedly add calcium to the soil when they finally do decompose, it is not recommended to add eggshells to your compost pile because they take so long to break down, which can slow the composting process down, and because they are known to attract rodents and other pests to the compost pile.

The one exception, where a study showed that eggshells actually can break down in a reasonable amount of time in certain environments, is when finely ground eggshells were added to an acidic soil base.

In a study in which large eggshell pieces were buried in a balanced soil medium and dug up after one year, examined, reburied, and dug up to examine again after three years, the eggshells showed no signs of decomposition after either one or even three years underground.

So, it’s hard to answer exactly how long it will take for eggshells to compost, but based on the three year study, it seems that eggshells decompose incredibly slowly and possibly even not at all.  

QUESTION: How hot does a compost pile need to be?

ANSWER: The ideal temperature for a compost pile is between 141 and 155 degrees F, as this is the temperature needed to kill weed seeds, disease pathogens, unwanted pests, as well as harmful fungus and bacteria. A hot compost pile will also speed up the decomposition process significantly. After you construct your pile, it should heat up to ideal temperatures within 24 to 36 hours. Once heated, compost can stay at high temperatures for several days and even up to a week or longer. 

If your compost pile isn’t heating up, it can be a sign that there is not enough moisture or too much moisture in your pile, or that there is not enough green materials in the pile. A properly maintained compost heap that heats up correctly should decompose and break down fully within about six weeks.

QUESTION: How do I control maggots in my compost?

ANSWER: Finding maggots in your compost may come as a surprise and can possibly gross you out a little bit, as most people consider maggots to be one of the most disgusting creatures they could possibly come across. However, despite their bad reputation, maggots are really not that bad, and can actually be beneficial to your compost heap, helping to speed up the decomposition process by feeding on organic materials and processing them into compost at a very quick pace. 

Maggots are the larvae of the black soldier fly, and they end up in your compost bin because the adult flies lay their eggs in warm places that have their own food supply, which makes compost piles an ideal place to place their offspring. As long as maggots have a warm and moist environment and plenty of organic material to feed on, they will thrive.

Finding maggots in your compost is a sign that you either have too many green materials in your compost pile and not enough browns, or that you are not turning your pile frequently enough, which can lead to moist pockets of kitchen waste that maggots can’t get enough of. 

You don’t have to do anything about the maggots in your compost, as they are not harming anything, but are actually helping your pile decompose at a faster rate. However, if maggots gross you out or if there are just too many maggots (which can actually be a significant problem), there are a few solutions which will combat the larvae infestation. 

One way to solve your maggot problem is to simply add more brown materials to your compost heap, which will dry out your pile a little and lower the percentage of available food matter, making it harder for the larvae to find materials worth feeding on.

Another solution is to add lime to your compost pile. Adding lime may cause your compost’s pH to raise up too high, but if you want to combat maggots, adding one cup of lime for every 25 cubic feet of compost or adding lots of pine needles or citrus fruit waste, any of which will handle your maggot issue, either by killing them, or by driving them out of your pile. 

Another way to handle maggots in your compost bin is to keep the black soldier flies from laying anymore larvae in your pile to begin with. To keep flies out of your bin, just cover your compost’s circulation holes with a fine mesh screen to keep flies from getting into your compost system. If they can’t get in, they can’t deposit their larvae, effectively solving the problem. 

The final way to handle maggots in your compost is to let them be. Maggots don’t hurt the final compost product, and having them in the bin actually speeds up decomposition, so unless you have a pet peeve about keeping them around, the best way to handle maggots in your compost is to let them help you break down your kitchen waste faster than ever before. The compost created with maggots is slightly less appealing.

It doesn’t have the standard rich, earthy, compost smell, but it’s just as high in nutrients as standard compost, and it processes much faster with their help. It’s understandable to want to get rid of maggots wherever you find them, but in the compost bin, they are doing more good than harm, so it’s best to just let them be. As the weather gets cooler, their numbers will dissipate. At this point, you can put mesh over the holes and avoid housing maggots in your compost in the future.

QUESTION: How can I make my compost less acidic?

ANSWER: Compost tends to have a pH level in the neutral to acidic range while the microbes in the compost are still working to decompose the materials. (The average pH range of compost in which microbes are still breaking ingredients down is between 5.0 and 8,) It is healthy and beneficial for the compost to be a bit acidic while the microbes are working. The pH level is considered acidic when it is less than seven. 

The acids in the compost will be neutralized during the decomposition process, and when the compost is complete, the pH range tends to be near the neutral zone, or between 6 and 8. So if you are concerned about the pH level of compost that is still decomposing, the best thing you can do is wait until the microbes have finished working, because the pH level of your compost may not need to be corrected at all. 

There are a few different reasons that compost can be too acidic once it has finished the decomposition process. If you’ve added more wet “green” materials that are rich in nitrogen without balancing them adequately with the drier “brown” ingredients that are full of carbon, the compost can increase in acidity and may also develop an unpleasant smell and break down more slowly than normal.

Acidity can also develop in compost if the materials used in the compost are themselves high in acid, such as if you’ve added lots of citrus fruits. You can correct both these issues by mixing in plenty of dry “brown” materials that are rich in carbon to balance out the acidity, especially if the compost is also too moist. Add a small amount of the wetter “green” ingredients when you balance things out so the compost will be triggered to start the process of decomposition again.

You should also be aware that the pH level of your compost is likely to vary depending on where in the pile the reading is taken from, just as the temperature does. To get an accurate pH test from your compost, take readings from samples in several areas and then either mix the samples together and test the combined sample or test each sample individually to get an idea of the range of pH levels that are present in your compost.

Although it may seem like a good idea to add the pH levels from each sample together and divide by the number of samples to determine the average, the average will not be accurate because pH levels are expressed as a logarithm.

If your compost becomes anaerobic, which means the compost  has no oxygen in it, the organic acids that naturally occur in compost will pile up instead of being broken down by the microbes. (This is because the microbes are unable to do much decomposition at all when the conditions in the compost pile are anaerobic. They need oxygen to survive and to perform their role of breaking the materials down.)

A compost pile that has become anaerobic may be wet, smelly, and black in color instead of rich brown. To resolve acidity in an anaerobic compost pile, simply 

turn or mix the compost to aerate it. For best results, you should be turning your compost every few weeks. Turning the compost on this schedule keeps oxygen available for the microbes and ensures your compost will be completed as efficiently as possible.

Experts warn against adding lime (also called calcium carbonate) to your compost in an attempt to correct an acidic pH balance and recommend using other solutions instead. When you use lime in your compost, ammonium nitrogen evaporates into the air as ammonia gas and is lost. This evaporation of ammonia when lime is used causes compost piles to stink and also decreases the level of nitrogen the compost will contain—and one of the reasons you’re making compost in the first place is to provide your plants with nitrogen.

However, other sources recommend adding ground limestone to your compost as a way of balancing out acidity despite this drawback. If you need to add something to your compost to reduce the acidity, we recommend using wood ash instead of lime. Incorporate the wood ash by adding several layers of ash interspersed with your compost every 18 inches.

There are a few different methods you can use to test the pH level of your compost. Whichever method you choose, make sure to measure the pH immediately after sampling so your reading isn’t affected by chemical changes that may take place once the sample is separated from the pile. 

• You can use any type of soil test kit on your compost without changing the way the kits are used. Just follow the instructions that are provided for testing soil to get a pH reading from your compost. 

• You can also opt for a pH indicator strip (also called pH paper) if your compost is moist but not sludgy or oversaturated. Simply push the pH strip into the compost pile, let it remain there a while to absorb moisture, then use the color comparison reading to measure the pH level.

• You can use pH paper or a calibrated meter to measure your compost’s pH by taking a reading from compost extract. Create the extract as follows: Spread compost in an oven-safe pan in a thin layer, then place the pan in an oven at 105 to 110 degrees Fahrenheit for 24 hours. Once the compost has dried in the oven for 24 hours, weigh out samples of five grams each into individual small containers. Add 25 ml of distilled water to each sample. Stir each sample vigorously for five seconds, then allow them to rest for 10 minutes before taking your pH reading with the pH paper or calibrated meter. The pH level of a sample tested in this way should be expressed as compost pH in water (pHw).