How Much Manure To Add To Potting Soil (And What Kind)?

Adding manure to potting soil can be beneficial but you need to know how to use it. I wanted to try using some in my container garden and you will find my research below.

It’s also best to mix the manure with potting soil. For most plants, you need to make a mixture of half manure and half soil for the best results. However, you can put the plants directly in it with excellent quality compost manure.

Add 20 percent manure to the potting soil. So if your potting soil is 10 pounds, add 2 pounds of manure to it. Avoid adding a lot of manure because it will harm the plants. Make sure the manure is aged and not fresh.

I’ve written a lot more details on how much manure to use, what options you have, and how to use the manure in the potting soil. So keep reading.

How Much Manure to Add to Potting Soil?

If you want to enrich your potting soil with manure, you’re going to have to a bit of careful planning. The goal here is to create a nutrient-rich potting mix that’s conducive to plant growth. Adding too much or too little can affect the way your plants develop.

As a good rule of thumb, your finished potting mix should be about 20 percent manure.

Figure out how much potting mix you’re going to need to fill your containers. Then, split that measurement up into fifths. One of those fifths will be entirely manure.

It’s important to note that this is just a general guideline. As I mentioned earlier, not all types of manure have the same nutrient content. You may have to make some adjustments if you’re using waste that’s higher in nitrogen or phosphorus.

If you’re using premade potting soil, infusing the manure is relatively easy. But if you plan on making the potting soil from scratch, there are other ingredients that you’re going to add.

Chances are, you’re going to have to add more manure than you originally thought. That’s completely normal.

It takes a lot of manure to bring nitrogen levels up to an acceptable level. Even in larger applications, such as a garden, you’re looking at several pounds of manure.

To put things into perspective, a 100-square foot garden bed could require up to 200 pounds of manure. That’s to add only 0.2 pounds of nitrogen to the soil.

Use the one-fifth rule to make things easy. You can always test the soil later and make adjustments to get things just right.

Can You Add Too Much Manure to Potting Soil?

It can be tempting to use as much manure as you can. The added nutrients can’t hurt, right?

Unfortunately, this is a huge mistake than many newer gardeners make. Too much manure can cause a litany of issues. The worst part is that many of those problems won’t make themselves known until several years later.

Here are just a few bad things that can come with using too much manure.

Nitrate Leaching

Nitrate leaching is a very serious problem that could affect the environment and your water supply.

When you first add the manure to your potting soil, nitrate levels are pretty low. However, the microorganisms in the soil convert the ammonia in the manure to nitrates.

Plants don’t use nitrates, so it just collects in the soil. Eventually, those nitrates will migrate through the soil and infiltrate the groundwater supply. There, they can wash away and wreak havoc on nearby streams.

Nitrates can kill marine ecosystems. Not only that, but high concentrations of nitrates in groundwater could cause poisoning in humans.

Excess Phosphorus

Another problem with too much manure is the accumulation of phosphorus. Plants eat nitrogen up no problem. Any nitrogen the plant doesn’t use can wash away or escape as a gas through the air.

However, phosphorus isn’t so eager to escape your soil. It only moves about an inch or two a year through the soil. As a result, it accumulates over time.

Several years later, that phosphorus could still be in your potting soil. So, the next time you plant something in it will be problematic.

Phosphorus is an essential nutrient. But, too much of it will inhibit the plant’s ability to absorb other nutrients. These include iron, manganese, and zinc.

Without those crucial nutrients, your plant will exhibit poor health and eventually die.

Overproduction

Overproduction might seem like a good problem to have. Unfortunately, you’ll pay for that bountiful harvest later on.

The season you apply manure may provide you with tons of fruit or flowers, but it will also result in unwanted growth. The plant could get leggy or experience a boost in greenery.

When the next season rolls around, your plant will struggle to keep up with the demand for all that new growth. So, it won’t have any energy to produce new blooms or fruits.

When to Put Manure in Potting Soil

Manure is cheap, readily available, and powerful enough to improve the soil in moderation.

That said, it’s not always needed. To avoid some of the issues I mentioned earlier, you have to know when to add manure to your potting soil.

Unamended Soils

The first thing you should consider is whether or not your potting soil could benefit from the manure in the first place.

If you recently bought your potting soil at your local garden center, there’s a good chance that its nutrient content is just fine. High-quality potting mixes are usually more nutrient-dense than basic soil in the garden.

In those cases, adding manure will only cause problems.

Consider testing your soil before jumping in with the manure. You can pick up a simple test kit to measure pH balance and figure out what nutrients are present.

It’s only when your soil lacks those essential nutrients that you should manure.

After Curing

Collecting fresh manure from farm animals? It’s best to let it cure before you start adding it to the soil.

Curing, or composting, is a step that you cannot miss. When manure cures, its ammonia and nitrogen levels drop down to manageable levels. This will help you avoid some of those aforementioned gardening issues.

The curing process also kills off the bacteria and harmful pathogens. You must cure any manure you’re planning on using for crop plants. This is especially true for plants you might eat raw.

Curing can take around six months if done correctly. During this time, the temperature of the manure will rise. It’ll also break down and start looking like traditional compost.

There’s no exact timeline here. Six months is the average. But, it can take up to a year if you let nature take its course. If you are proactive about speeding up the curing process, it may take as little as three or four months.

It all depends on curing conditions. You’ll know that the manure is ready when it’s dark and crumbly. It should have a similar texture to the soil.

How Do You Add Manure to Potting Soil?

Adding manure to potting soil is as simple as it sounds.

Figure out how much total soil you need. Then add one part manure to four pots soil. Mix everything up with a trowel and you’re good to go.

Creating Potting Mix from Scratch

Now, if you want to create your very own potting mix with manure, there’s a bit more work involved.

Start by gathering your materials. You will need one part manure, one part vermiculite, one part coarse sand, and two parts of dry topsoil.

In a large container or wheelbarrow, sift the manure. By this point, the curing process is over and the manure is ready to go. However, the screening will get rid of any manure that did not decompose properly. It’ll also get rid of any stray twigs or debris.

You can use a piece of steel wire. It doesn’t have to be perfect. The goal is to just get rid of large chunks that could ruin the texture of your potting mix.

After sifting, you can add the coarse sand and vermiculite. Then, restore your sifting apparatus and take care of the topsoil. Get rid of any debris from the topsoil so that your mix is nice and uniform.

Using a shovel or gloved hand, give all of the ingredients a good mix. You should have a nutrient-rich DIY potting mix that’s ready for plants.

Adding Fresh Manure

Cured manure is a must-have if you plan on adding plants right away.

However, you can use fresh manure to prepare the soil for the future. This is a common practice among farmers. Many will incorporate manure into the soil during the fall months.

This gives the manure ample time to cure over the winter. The ammonia will dissipate and leave behind all of the good stuff.

Just add the manure to the soil and mix it up evenly. Then, let the potting soil sit until next spring.

What Are the Different Kinds of Manure You Can Add to Potting Soil?

Manure can be a stinky solution to your soil issues. However, you have to choose the right one for your needs.

Gardeners and farmers utilize several types of manure to amend their soil. Here are some of the most popular options.

Poultry Manure

If you have access to chickens, turkeys, and other domesticated birds, you have a goldmine on your hands.

Chicken manure, in particular, is very high in nitrogen. As a result, it works well for a wide variety of plants. Just make sure to cure it first. Poultry manure can easily burn plants if applied fresh.

It’s also important to consider any chemicals or antibiotics the chicken had. Those antibiotics could make its way to your plants.

Cow Manure

Cow manure is a tried and true option. Often sold in stores, cow manure is readily available even if you don’t have cattle of your own. It’s not as high in nitrogen as chicken manure. But, it still has plenty of beneficial nutrients.

This type of manure can carry weed seeds and hormones depending on where you get it from. That said, it also has tons of beneficial bacteria.

Pig Manure

Pig waste is hot manure that needs to compost with a carbon-rich material before you use it with your potting soil.

Pig manure is very strong. It works best alongside other types of manures. You can also mix in some plant matter for additional support.

Fish Manure

Fish manure doesn’t look like other options. Like fish meal, it has high concentrations of nitrogen. However, potassium and phosphorus levels are low.

This is a fast-acting fertilizer. It’s best for giving your plants a boost of fertilization rather than the slow-release of other manures.

Sheep and Goat Manure

Because sheep and goats usually survive off of grains and hay, this manure is very rich. It’s usually dryer than some other manure products, which can make it a bit easier to handle.

Can You Mix Manure With Potting Soil?

Properly cured manure is a wonderful addition to plain-old potting soil. It acts as a soil amendment to improve its overall quality.

That said, isn’t always the miracle product that some gardeners think. While it can do a lot to benefit your plants, it’s not suitable for every gardening application.

Before you start mixing manure with your potting soil, here are some advantages and disadvantages to mull over.

Advantages

Manure has the potential to breathe new life into lifeless soil. It increases soil carbon, which can enhance the growing medium’s fertility.

Carbon does a lot to change soil for the better. Not only does it help with water retention, but it feeds the beneficial microorganisms in the soil. As a result, the nutrients that are already within your potting soil become more available for the plants to use.

Manure itself can act as a fertilizer. It’s rich in key nutrients like nitrogen, phosphorus, and potassium. If you’re familiar with commercial fertilizer, you already know that those nutrients are crucial to good plant growth.

The cool thing about manure, however, is that its a slow-release fertilizer. Those nutrients take time to break down, which gives your soil some long-term benefits.

Disadvantages

Despite all of the good it does, there are some caveats with using manure in your potting soil.

The first is its potential to burn plants. Fresh manure has very high levels of nitrogen and ammonia. If applied incorrectly, it’s capable of burning plants much like excess fertilizer would.

There are different types of manures that you can use, which we’ll get into a bit later. Some types are going to have lower nutrient levels than others. But regardless of the type of manure you use, it’s important that it’s properly cured.

That’s because manure could still have contaminants and pathogens. Everything from viruses to parasites could invade your soil if you use uncured manure. That’s not something you want in your plants.

Can You Plant Directly Into Manure?

Growing plants in nothing but manure is possible. But, you’re not going to get the results you’re after.

Manure is full of nitrogen. When you mix it up with potting soil, you’re essentially diluting it. This ensures that your plants can take advantage of the nitrogen they need without getting too much of it.

If you were to let your plants grow in just manure, that excess nitrogen will cause some problems.

Nitrogen contributes more to foliar growth more than fruit production. It certainly helps to develop flowers and fruits. But most of it is going to the stems and leaves.

Your plant will flourish. Unfortunately, you’ll only see larger leaves and more stems. Any flowers or fruits that could have grown will not have the energy to do so. The plant is will use the nitrogen to double down on the foliage rather than the crop.

What is the Difference Between Manure and Fertilizers?

Many use the terms “manure” and “fertilizer” interchangeably. While similar, these are two different things. Knowing how to distinguish between the two will help you make the right decision for your garden.

Manure is a soil additive. It’s something that you mix with your soil to improve its quality. Think of it as a soil fixer. You add it to the growing medium before you start planting to ensure that your crops have full support as they flourish.

Whether you get your manure from a cow or chicken, it’s completely natural. Thus, it doesn’t harm any organisms in the soil.

Now, fertilizer is also a soil additive. However, it’s more of a quick solution to growth problems. Manure targets soil issues from the start. Fertilizer is something you would use to address problems while your plant is growing.

Many fertilizer products are also chemical-based. This isn’t always the case, as there are plenty of organic fertilizers out there. But most commercial products will contain some type of chemical.

Chemical formulas have the potential to kill healthy organisms in the soil and have long-term effects on the growing medium.

Slow vs Fast Absorption

Here’s where things get tricky. Manure can act as a fertilizer depending on how you use it. But, not all fertilizers contain manure.

Confused yet?

The easiest way that I like to separate manure from fertilizer is how the plant absorbs it. Plants use fertilizers quickly. Even if you use a “slow-release” product, it will take only six to eight weeks for those nutrients to go away.

Manure, on the other hand, can last years. It’ll continue to improve soil quality long after you mix it in. Plants absorb the nutrients slowly for long-term growth.

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