Is home compost acidic or alkaline?

Also: How do I make compost more acidic?

How do I reduce the acidity in my compost?

Compost that you make at home is unlikely to be alkaline. Home compost will either be slightly acidic or very near neutral. If you have compost that shows an acidic level of lower than 7 on the pH scale, then, add white lime to achieve a neutral pH. The pH scale indicates either acidity or alkalinity.

A lot of people worry about the risks of using acidic compost and any adverse effects that it may have on plants. There’s a concern that, with soil possibly being acidic, there’s a risk that the combined effect will kill plants.

This could happen. But having such acidic soil conditions, whether from the soil or the addition of acidic compost, that kill plants, would be quite an achievement.

What you are more likely to see are plants that don’t appreciate acidic soil conditions, merely under performing. They won’t look their best.

I’m hearing that some people are buying electronic devices that will give a digital reading that shows how acidic their compost is. Some are taking samples and sending it to a laboratory to be tested.

There’s no point in doing any of this. If you test the pH level of compost in the early stages, it’s very likely that it will show as being acidic. An experienced eye will detect if home compost is more acidic than it should be.

Hydrated white lime can be added to lower the acidity and possibly take it beyond the neutral pH of 7 and make it alkaline.

There is no point worrying at all about compost being acidic while kitchen waste is being converted into compost. This will be due to the natural sequence of events that occur during the compost making process. In the early stages there will be an element of fermentation.

It won’t last long but when it does it will generate acids. At this point the pH reading will be way lower than the neutral of 7, indicating acidity.

With the addition of carbon ’brown’ material, you will establish a balance of ingredients in the compost that will raise the pH level to be nearer to the neutral of 7. This will happen without too much effort from you.

Is home compost acidic or alkaline? It’s usually acidic.

This is one of the reasons why compost takes a while to become compost. Much of the time that’s taken up will be to do with the acidic element needing time to become ‘worked’ out. By the time that the composting process has completed you can expect to have access to a finished compost that will register a neutral 7 on the Ph scale.

Some will tell you that the pH reading of finished compost will show a measure between 6 and 8. Meaning that your compost could be either acidic or alkaline when finished. This can happen and will, no doubt, cause confusion.

For compost to become compost, It must be as near as possible to the neutral of pH 7. A slight fluctuation one side or the other is allowed. Low level acidity won’t hinder the process any more than a low alkaline level.

And that’s the point. If you have achieved compost that’s black and crumbly with no smell to speak of, then you will have compost that’s made up of the right balance of materials.

So, we come to the question that some people have about using compost to adjust the acidic or alkaline levels of the soil that we have. Is this practical? The nature of the composting process can sometimes deliver compost that will be on the acidic side of neutral on the Ph scale.

Depending on how much carbon’ brown’ material you add, the acidity generated in the early stages, may overshoot the neutral pH 7. This may be why a sample of compost may show indications of being alkaline.

Most times there will be an acidic element in there that will counter the alkaline level of the soil to a degree. It won’t be enough to make a massive difference but it will be all that you could expect from a home compost material that has gone through a process that takes it from being acidic to almost neutral on the pH scale.

If the soil is acidic, higher than we would like, it wouldn’t be realistic to expect the adding of home compost to bring the acid level down. In home compost we’re handling a material which, in its finished state, will be just one side or the other, of neutral. Any desired effects of adjusting acidic or alkaline soil using home compost will be minimal.

How do I make compost more acidic?

You can make compost more acidic by adding organic materials that have an acidic tendency. This would include pine needles, coffee grounds and oak leaves. If you specifically want a compost that’s more acidic, then, don’t add hydrated white lime. Allowing more ‘greens’ than ‘browns’ will make for more acidic compost.

If you know that you will need a compost that’s more acidic than the basic compost that you would expect from a balanced mixture of inputs, then you need to make a plan.

Acidic compost can be generated by selecting and managing the materials that you intend to make compost from. Any organic material can be turned into compost. All organic materials have the propensity to rot. Some organic materials will generate a higher acidic level than others. To make acidic compost, these are the materials that we need.

Acidic compost needs planning from the start

There are many plants on the forest floor that prefer acidic soil conditions. On the forest floor, there will be a build-up of rotting vegetation that’s accumulated from previous growth. It’s this growth and the type of plants involved, that will generate the more acidic conditions that we’re looking for when they rot into compost.

One group of plants that need acidic soil is ferns. Where you see wild ferns growing, they always seem to grow well. This is partly because the fern is very successful at smothering the ground and holding down the competition.

But there’s another reason. Ferns die down at the end of each growing season and provide a large bulk of rotting material. Rotting ferns generate acidity. This is very convenient for the fern.

Find out about the Rolypig composter

If you can acquire a decent quantity of dead ferns, then you could make a meaningful amount of acidic compost.

It’s important to note that there have been some reports of dust particles from ferns being responsible for cancer.

For this reason, do not be tempted to shred dead ferns. This will avoid the dust. Make dead ferns wet before handling them to eliminate the risk of dust. When you put dead ferns in the compost bin, they will rot down with the rest of it.

Because of any potential risks, It may be wise to gather all the ferns that you have into one compost pile, heap or bin. Doing this will avoid regular handling of it when you visit your compost bin that’s taking your kitchen waste.

Ferns will convert into compost without having to add anything except water to keep it moist. Normal composting rules apply when making compost from ferns. It will help speed up the process if you dig the heap over but leave this until there are signs that the compost is in an advanced state of decomposition.

This will reduce the risk of any potentially harmful residues that may be held in fern compost heap that has somehow remained preserved as dead ferns.

Another group is conifers. These produce masses of pine needles. With these you have another option. If you can gather a large quantity of these you can store them. There are no known health risks with pine needles.

You can then use them to make compost more acidic by adding them to your regular deliveries to the compost bin. This way the finished compost will become a mixture that includes a plentiful distribution of pine needles.

Is multi purpose compost acidic?

I’ve looked around to find an answer to this. There doesn’t appear to be an answer. It seems that the only way you can find out if multi purpose compost is acidic or alkaline is get a bag of multi purpose compost and do a litmus paper test.

Multi purpose compost may not be acidic

The general assumption is that all multi purpose composts are pH neutral. If we want a compost that is specifically acidic, to match the needs of acid-soil desiring plants, then we need to look at a type of compost known as ericaceous compost.

Do you know what ericaceous is? I didn’t, until I started looking into the need for acidic compost. Ericaceous describes the category of plants that are of the genus Ericaceous.

This particular group grow and perform at their best in acidic soil.This is where an acidic compost, rather than alkaline, is required. Ericaceous compost has to be made from ingredients that generate a compost that has a low Ph level, meaning that it’s acidic and certain not to be alkaline.

The advice for this is to include oak leaves, pine needles and coffee grounds. You can also use ferns, if you can get them and feel happy about using them. If used in sufficient quantities, these are an example of ingredients that should generate an acidic sample of compost.

The type of plants that benefit from acidic soil and compost include Rhododendrons, Azaleas, Hydrangeas, Holly.

There are some fruit bearing plants that fall in the same category. These include Blueberries, Cranberries and Raspberries.

How do I reduce the acidity in my compost?

To reduce acidity in your compost you need to avoid anaerobic digestion. Acidity in compost can also be reduced by focusing on securing a balance of carbon ‘browns’ and and night rate ‘greens’. The ultimate way of of reducing acidity in compost, is to add hydrated white lime.

It’s easier to reduce the acidity of compost than to increase it. When making compost we have to aim to achieve the right balance to encourage decomposition. We have to balance the nitrates in the mix with carbon based material.

The ratio we should be aiming for is 1 unit of nitrate ‘greens’ to, at least, 20 units of carbon ‘browns’. Too much of the nitrate ‘greens’ will lead to acidity but you can reduce it by adding a liberal amount of hydrated white lime.

It’s easy to reduce acidity in compost

The action of hydrated white lime is direct and positive. It will react with any acid in any circumstances. It will reduce acidity in compost with the process taking an immediate effect. Adding hydrated white lime can go a long way towards compensating for a short-fall in carbon ‘brown’ material being added to the mix.

Any organic material that’s being steered away from acidity will decompose into a neutral pH compost, regardless of how it’s done.

Making compost in the Rolypig compost tumbler

This is one of the easiest ways of turning kitchen waste into compost. You feed the Rolypig with kitchen waste together with shredded newspaper or small pieces of cardboard.

The thing about the Rolypig compost tumbler is that you don’t need to feed so much of the carbon ‘browns’. You can tame any acidity by feeding it with a regular dose of hydrated white lime. This will neutralise the acid. The number of worms present is evidence that this is happening.

The Rolypig sits on the ground. This means that worms have easy access to the compost. The Rolypig that I have, is half full of compost and there is a massive population worms. If the compost was too acidic, the worms wouldn’t go near it.

Feeding the Rolypig is easy. You feed it at the mouth end. You only need to roll it over when it becomes difficult to get any more kitchen waste in. You only need to give it half a turn to make more space inside, then carry on feeding.

The Rolypig compost-tumbler never needs to be emptied. It works at its best when half full. The barrel can’t reach more than half full which means that it never becomes so heavy that you can’t roll it over.

When it reaches the point where it’s so full that you can’t get any more kitchen waste in, this is the time to start taking out compost from the rear door.

When I take out compost from my Rolypig, there’s always a lot of worms mixed up with what I take. I don’t attempt to return any of them to the rest of the compost that remains inside the barrel. The population of worms in the compost is massive. Those that I take out won’t be missed and they will be moved to ‘pastures new’.

The compost that comes out of my Rolypig generally takes about 16 weeks to move from the mouth end to the rear. During that time it will have had hydrated white lime added to it. It will be regularly agitated by the occasional rolling over and it will be digested by worms.

Manage it as it needs to be and the compost that emerges from the rear of the Rolypig is likely to be the best that you will ever get hold of.

Another trick that I’ve learned about making compost is that dried yeast appears to make a difference. For reasons that I won’t go into here, I found it necessary to dispose of some dried yeast. I fed it to the Roypig, just to get rid of it.

I had no idea what it was going to do to the compost inside the Rolypig. Yeast is a fungus. It appeared to feed on some or all of the fresh waste. Going mouldy is the first stage of the composting process.

The next stage is the worms move in, if they are there. They will digest the compost and take it to another and possibly the final stage. The yeast appeared to accelerate the breakdown of the fresh kitchen waste. The worms were able to digest the compost during and after the yeast effect.

It was noticeable how the level went down, making more room which allowed for more kitchen waste to be fed into the Rolypig.

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