Cottonseed Meal: A Trash To Treasure Fertilizer Story

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We all know cotton is a valuable material worldwide. But its byproducts, like cottonseed meal, have value too!

With more and more people growing their own food, cotton seed meal is increasing in use. As a fertilizer option, it’s a slow-release pick. It provides more organic matter to your soil, too. And with over 14 million pounds of it produced every year, it’s constantly renewable!

Let’s cover the myriad of uses for cottonseed meal. We’ll talk about how it’s made, where you can buy it, and how to use it properly!

Good Cottonseed Meal Varieties:

What Is Cottonseed Meal?

cotton field
A cotton field with the cotton bolls in full bloom. Source: Martin LaBar

When cotton is grown, it produces bolls. These bolls are filled with fine, soft material that grows over the seeds. If left in place, that soft cotton acts as a seed-dispersal method.

As we use that fiber for our clothing and fabrics, we of course don’t allow it to go blowing away on the breeze. We harvest the cotton. And in so doing, we have huge quantities of cotton seeds.

Rather than allow those seeds to go to waste, since there’s too many to plant, we use them in other ways. We extract oil from them, and the resulting meal has been used for animal fodder. But it makes great fertilizer, too!

How Is Cottonseed Meal Made?

unginned cotton
Unginned cotton, showing some of the seed and particulate in the cotton boll. Source: Midpath

Once harvested, cotton goes through processing. First, it’s air-dried to make the material easier to process. Then it goes through the ginning process.

A cotton gin pulls the fibers through fine-toothed combs that remove the seed. This also removes any remaining leaves or other plant waste from the soft cotton.

While the rest of the cotton moves on through the process, we’re now left with an abundance of cotton seeds. These seeds go to another location to remove the hulls and extract the oils.

Two forms of oil extraction processes are commonly used: solvent, or press.

In solvent extraction, different liquids are used to draw the oil out from the seeds. The seeds are sterilized in the process. Often, there’s still some oil remaining, making them higher in protein and fat. Solvent-extracted seed meal is often used in livestock feed.

Press extraction is exactly what it sounds like. Using a strong press, the oil from the seeds is forcefully extracted. This can be its own separate process, or performed before or after solvent extraction.

What remains after the oil’s extracted is the cotton seed flour or meal. Cotton meal is then dried and sold as a loose meal. It also can be compressed into cake form, which makes it an easier size for animal fodder. The cake form contains more remaining oil than the meal does.

The hulls that are removed before oil extraction aren’t wasted! Cottonseed hulls are often used as mulch in landscaping. As they break down, they release nutrients into the soil as well.

Benefits Of Cottonseed Meal Fertilizer

earthworks cottonseed meal
A closeup image of Earthworks Cotton Seed Meal, showing the ground seed particulate.

Cottonseed meal fertilizer provides a healthy kick of slow-releasing nitrogen, potash, and phosphorus. The heavy protein in the cotton meal slows decomposition. Soil microbes have to process the proteins to release nutrients the plants can use.

Because of its slow-releasing nature, you can use higher quantities of cottonseed meal. There’s no fear of fertilizer burn with this, making it a safe and sustainable long-term option. And it takes 1-4 months for it to fully break down, so applications can be spaced out.

The average NPK for this meal is 6-2-2, making it a viable nitrogen option. Different manufacturers have slightly different ratios of nutrients. It’s wise to check the label for your specific brand.

Since it has high organic content, it helps to keep the soil aerated. This reduces compaction in the soil and can help plants to thrive. Soil tilth greatly improves with added organic matter.

Cotton meal holds quite a bit of water when saturated. This makes it a great amendment for water retention in garden beds!

As well as having a high nitrogen content, cottonseed meal also has many trace minerals. These trace minerals vary widely, but all aid in plant growth.

If your soil is too alkaline, add some cotton seed meal to the bed! It lightly acidifies the soil, which can neutralize soil pH.

Drawbacks Of Cottonseed Meal Fertilizer

Just as it’s a benefit, the acidifying nature of cottonseed meal can be a drawback. For every 100lbs of meal used, 9lbs of agricultural lime is needed to bring the soil back to neutral. Acid-loving plants like blueberries will love the more acidic soil, though! Be sure to check your pH before adding cotton seed meal.

If it’s stored in a humid environment, this meal is at risk from molds. Be sure to keep it in a dry, sealed container when not in use.

As cotton is in so much demand by the textile industry, it has another downfall. Many cotton crops are heavily treated with chemicals to protect against insect damage. This means that the seed meal may have pesticide residues.

While there may be traces of pesticide in the meal, it’s very limited. Most of the pesticides will be on the cotton itself rather than the hidden seeds, or on the plant’s foliage. Very rarely will it actually make it to the seeds themselves.

But it is something to take into consideration. Some states do not consider cotton meal to be a viable organic option for growing produce due to that slight risk. There is OMRI-rated cottonseed meal available, but it can be difficult to find.

Finally, cottonseed meal contains a naturally-forming compound called gossypol. This isn’t a drawback as a fertilizer. However, if you use chickens as pest control, it might become a problem to them. Gossypol can become toxic for livestock in large quantities! Cottonseed meal should only be fed in limited quantities to poultry (5% for layers, up to 10% for broilers).

If you do raise chickens, it’s best not to top-dress your beds with cottonseed meal. Work it through the soil to prevent your chickens from eating your fertilizer!

How To Use Cottonseed Meal

pima cotton seeds
Whole Pima cotton seeds. This is what they look like before oil extraction. Source: staceyjoy

Since cottonseed meal doesn’t burn plants, it’s safe to add larger quantities. It will provide consistent, slow-release nutrition for your plants.

Before planting, a good rule of thumb is 2-4lbs per every 100 square feet of soil. If your soil is particularly poor, you can go as high as 8-10lbs. This doesn’t have to be exact, but it’s a good estimate!

Work the meal into the top 2-3 inches of soil. This ensures you have a good soil to fertilizer blend.

Looking to fertilize plants that’re already started? There’s a basic formula for that, too!

New transplants should have 1 cup of cottonseed meal worked into the soil around their root zone. Other younger plants that are already planted will benefit by having a cup of meal added, too.

Older, established plants can take 2-4 cups of meal depending on the size of the plant. This can be used as a top-dressing or can be worked into the soil.

Fertilizing lawns with cottonseed meal is an option! You can broadcast the meal over your turf by hand or using a spreader.

Don’t forget your fruit trees or shrubs. Because it also contains potassium and phosphorous, this meal helps promote fruiting. If you’re looking for a larger harvest or healthier fruits and plants, work some meal into the soil there as well!

Regardless of how you’re using it, be sure to water it in generously once applied. This starts the decomposition process that allows the meal to become plant food.

Can I Make Cotton Meal Tea?

To extract the nutrients from this meal, a microbial population has to be in play. It’s not water-soluble.

This means that while you can add small amounts of cotton meal to your compost tea, it won’t add to the fertilizer. It does provide food for the microbial population you’re breeding in your compost tea!

It’s best to put your meal to work directly in garden beds rather than to try to extract the nutrition to a liquid form. The meal acts as a soil conditioner, so it’s most effective that way. You can also use cottonseed meal as food for composting worms!

Where To Buy Cottonseed Meal

cottonseed meal
A view of Down To Earth brand cottonseed meal, described as having the consistency of coffee grounds.

You can find cotton seed meal at most garden centers. Multiple big box stores have been carrying it, too.

But if you’d like your meal dropped off at your doorstep, that’s definitely an option. Here’s a few of the top brands available right now!

If you only need a small quantity, Espoma Cottonseed Meal may be your best bet. This comes in a resealable 3.5 pound bag. People who’re growing acid-loving plants in pots, rejoice!

Amending your larger gardens or multiple pots? Down To Earth Cottonseed Meal comes in a 6 pound box. Larger quantities of their product are also available.

If you’re looking for quantity, there’s Earthworks Health’s 50-pound bag of cottonseed meal. This is great for people with larger spaces to fertilize. It’s also wonderful for lawn amendments.

Cotton seed cake is harder to find. While it is available, it’s often blended with other ingredients and sold as feed. Since ruminants can’t eat a steady diet of only cotton seed, this is a safer option as feed stock. You can sometimes find it at feed stores.


Looking for an excellent source of slow-release nutrition? This meal should fit most people’s needs. Have you ever used cotton meal in your garden? Do you find it too acidic for your plants? Tell us about your experiences in the comment section!


The Green Thumbs Behind This Article:

Johnny Harvill
Homesteader

Lorin Nielsen
Lifetime Gardener

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Last update on 2019-11-11 / Affiliate links / Images from Amazon Product Advertising API