Healthy soil is the foundation for building a thriving garden. Without the right nutrients in the soil, a successful growing season will be impossible. Not to mention, a wilting garden is frustrating.
While most soil contains everything plants need to be healthy, over time, that soil can be overworked and the nutrients depleted, so that very little life exists. This is especially true if using raised beds or container gardens and soil can lose significant nutrients if no amendments (like compost or mulch) are added each season.
We rounded up as many ways possible to improve the nutrient content of your soil – most of which are relatively easy to incorporate and are free or low-cost.
How Do I Know What I Need for Soil Fertility?
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Soil fertility goes beyond just the nutrients that come in manufactured fertilizers, like nitrogen, potassium, and phosphorus. It also has to do with the level of microorganisms that are in the soil, along with things like beneficial insects. Soil fertility also relates to organic matter, drainage, nutrient ratios, pH, and texture.
A good indicator of fertility is soil that is dark brown or black. It will be loose and crumbly in your hands and have a pleasant, earthy flavor (if you’re into trying it). If your soil is infertile, it will be hard, dry, pale, and difficult to dig. It might be soggy or experience lots of erosion or run-off, too.
If your soil is poor, try not to feel too badly about it. Often, it’s not your fault. Things like compaction, erosion, pesticide use, overgrazing, and fertilizing can all cause issues with fertility. Even something as simple as growing the same crops, year after year, can deplete the soil of nutrients.
Test Your Soil First
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Before you try any of the fertility-boosting methods below, make sure you take the time to test your soil. It is impossible to know which nutrients your soil is lacking without doing a test. You can purchase a test kit and do this at home yourself, or you can take a sample and send it off to your local cooperative extension.
In most cases, it pays to take a sample from a few different areas in your garden – especially if your garden is quite large or you have never worked it before. You should test your soil every few years just to make sure it remains fertile and balanced. Once you know what the soil is lacking (or has too much of), you can decide which of the following items below will be most useful for your garden.
1. Fix the Texture First
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Check the texture of your soil before you work to amend it. While loam soil (a mix of sand, silt, and clay) is generally quite fertile, you will have trouble with other textures of soil (like clay and sand) as they tend to hold nutrients poorly.
Figure out what kind of soil you have to give you an idea of fertility. Sand tends to drain water quickly, while clay soil holds it. Loam and silt will be loose in your hand, but still moist.
If you want to amend clay soil, you will need to add organic matter to the ground each year. This will help improve fertility and drainage. Sandy soil can also be improved, but you’ll also need to use cover crops to improve its structure, too, since it’s so loose.
2. Practice Good Crop Rotation
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Avoid planting the same crops in the same spot, year after year. Not only is this a great way to attract pests and diseases (many can overwinter in the soil), but it also depletes the soil of necessary nutrients.
In order to rotate efficiently, keep track of the types of plants you’re growing in each section so that you can come up with a system for rotating. We recommend rotating crops from different botanical families (along with their companions) to interrupt pest and disease cycles.
3. Add Manure
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Sure, it may not smell the greatest, but manure is one of the best ways you can make soil fertile. It adds nutrients to the soil and also has the ability to improve its texture. Just be mindful of what and how you add it.
According to the Farmer’s Almanac, the most common sources of manure are cows, horses, sheep, pigs, goats, and poultry. Depending on what the soil needs, manure is often composted first to reduce its nitrogen content and chance of burning plants. Ultimately, it will depend on what nutrients and organic matter the soil specifically needs.
4. Add Compost
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Good old-fashioned compost is the agility-boosting method that everyone has heard of. Try to age your compost for at least one year before you use it in your garden, especially if you’ve used ingredients high in nitrogen, like chicken manure.
No matter how you choose to compost, it will have a ton of benefits for your garden. Just make sure your compost has the right combination of carbon to nitrogen – ideally 30 parts carbon to 1 part nitrogen to prevent burning your plants.
You can add all kinds of ingredients to your compost pile, including chicken manure, kitchen scraps, yard clippings, dried leaves, and wood shavings. Wet the pile occasionally, and be sure to turn it – and add to it on a regular basis! You can use compost before planting, at the beginning of the season, or even just add it to the planting hole when you plant your seeds like gardeners do with trench composting.
5. Try Compost Tea
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Compost tea, or liquid compost, is another way to add nutrients to your soil.
You can make your own compost tea with compost or worm castings, and then apply it after you have planted your seeds. It’s a great “touch-up” fertilizer. In fact, it can be used throughout the entire planting season.
Additionally, if you do have a vermicomposting system at home, you should save the worm castings and apply them to your garden. They’re totally organic and can improve the fertility of your soil by adding phosphorous, potassium, magnesium, calcium, and more. They can also improve the soil texture and moisture retention. A win-win!
6. Fish manure
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Have a fish tank? Recycle the manure!
All you need to do is save the water each time you change the supply. You’ll be able to give your plants the nitrogen, potassium, and phosphorus they need to be healthy. You can also find fish emulsion (ground fish byproduct and bones). However, you’ll want to make sure it comes from a good source and not fish farms filled with pesticides and antibiotic residue.
7. Alfalfa Meal
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Alfalfa meal contains roughly 3% nitrogen and is a great way to add this nutrient to your garden. Although it can be somewhat expensive, it is the perfect solution for a small, nitrogen-deprived garden.
You can look for it in your local gardening or farming center or order it online. Ground powders tend to work better for gardening. However, if you have pellets around for animals you can try throwing a few in the soil.
Another option is a soybean meal.
8. Leaf Litter
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Autumn leaves are a great source of carbon and other nutrients for your garden. They can be used as mulch or included in compost. Stop throwing them in garbage bags and sending them to the dump.
Not only will you save on disposing of your leaves, but you may be able to help out your neighbors by taking a few off their hands, too.
9. Fireplace ash
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Save the ash from your fireplace or fire pit. As long as you did not use wood that was treated with any chemicals, you can use it in your garden. It will add potassium as well as calcium.
You can add it to compost, sprinkle it on soil, or even use it as a top dressing.
10. Seaweed
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If you live near the sea, seaweed is a great way to fertilize your garden. It is not only free from chemicals, but it’s high in nitrogen. It’s also high in vital macro and micronutrients like potash, magnesium, phosphorus, and sulfur, too.
Usually, seaweed is used dried and raw as a mulch. It can also be added to water to make a liquid fertilizer or to compost.
11. Hugelkultur
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Hugelkultur is a way of improving soil fertility by burying large pieces of rotting wood. It’s a great way to introduce nutrients to the soil and is ideal for raised beds.
Plus, you won’t have to pay for all of that extra unused soil to fill in the beds.
12. Mulch
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Mulch of any kind serves a ton of purposes in the garden. Not only does mulch help prevent weed competition, smoothing out any nearby weeds that may cause you problems, but it also helps to retain moisture during the driest times of the year. It also boosts fertility, as long as you choose the right kind of mulch.
Wood chips and hay are some of the best mulches for your garden. If you choose hay or straw for a mulch, just make sure your selection is weed-free. You can even use a thick layer of compost as a mulch!
Avoid using mulch from certain types of trees, like pecan, black walnut, and hickory, as these mulches can kill some types of plants. When you mulch, make it two to three inches thick. Keep about an inch away from the base of your plants to prevent rot.
13. Blood meal
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It sounds a bit unsavory, but don’t be afraid to get a bit bloody in the garden (literally). Blood meal can be expensive if you buy it from the store, but you can easily make your own by saving blood when you butcher chickens, deer, or other animals.
It has a lot of nitrogen, so you’ll need to be careful about using it where you have plants actively growing.
A good rule of thumb is to either add blood meal to a fresh compost pile – where it will have time to break down before being added to the garden – or to add it in the fall so it has several months to be worked into the soil before you need to plant. Other “meals” include feather meal, bone meal, and kelp meal.
14. Coffee grounds
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Coffee grounds are perfect for soil. Not only do they add potassium, copper, magnesium, and phosphorus, but they can help make your soil more acidic, too. For the best results, use unbleached coffee filters as they’ll break down better in the soil.
Many plants will benefit from the coffee grounds after they’ve been well-composted. However, some plants love the acidity, such as blueberries and azaleas. They can also deter pests like slugs and snails.
15. Banana peels
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Have a few extra banana peels lying around once the banana bread is in the oven? A good way to get rid of all of those peels is to either compost them or put them directly in the garden. Other popular options include drying the peels to make a powder or steeping them to make a tea.
If you plan to place the peels directly in the soil, it’s advised to chop them into a mulch and bury them in the soil or mulch to keep unwanted pests at bay.
16. Sodium or Chilean nitrate
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Sodium nitrate and Chilean nitrate are two fertilizers that act like synthetic fertilizers, yet are approved for organic gardeners as long as they comprise less than 20% of the nitrogen used.
You should use these sparingly, as they can cause sodium buildup in the soil. However, they work more quickly than most other nitrogen additives, and so are something you might want to consider in a pinch.
17. Get those chickens going
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Not only does chicken manure serve as one of the best natural fertilizers there is, but chickens also do a great job of tilling up the garden, too.
Once you have harvested your plants in the fall, simply set your chickens loose. They will add their manure to the garden as they scratch for bugs, and since it will be such a long time before you need to plant again, you won’t need to worry about the nitrogen burning your plants.
Plus, chickens will eat pests and bugs that tend to overwinter in the garden. This will reduce your reliance on pesticides in the following year!
Chickens can even turn under old, decomposing bits of vegetables, plant scraps, and wood chips that were piled into the garden. Throw out some compost, and they’ll work that in for you, too.
18. Eggshells
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Eggshells are rich in calcium and can be added to the soil both at planting time as well as when you are building your compost. The sharp pieces even help to keep some pests away! They add other nutrients to the soil, too, like magnesium.
Most gardeners will break them up, or even crush them into a powder if they plan to add the shells directly to the soil for a nutrient boost and pest control.
19. Implement lasagna gardening
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Lasagna gardening, also known as sheet mulching, serves several purposes. Not only does it totally eliminate the need to till your garden – which I’ll address in a minute – but it also helps fertilize your garden and prevent weeds.
Lasagna gardening smothers weeds, making it easier for you to plant a garden, and it also allows helpful insects and bacteria to thrive.
All you need to do is layer organic matter, like leaves, compost, yard waste, hay, and manure. The bottom layer of your lasagna garden should be plain cardboard or even some wet newspaper.
Wet all of your layers when you’re done, and wait a few weeks. Then, you should be able to plant right into the layers
20. Utilize plants’ taproots
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Some plants have deep tap roots that can help extract minerals that are harbored deep below the surface of the soil.
When these plants die, they leave behind their nutrients and minerals, placing them back into the soil where smaller plants can easily get to them. The taproots improve aeration and create channels in the soil, helping give oxygen, water, and nutrients to plants with more shallow roots. This is especially helpful in clay soil.
Some plants with deep taproots for you to consider include dandelion, yellow dock, and borage. Some people view these as weeds, but don’t jump on this bandwagon! They actually have a ton of benefits and most of these are edible, too.
21. Use cover crops
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Cover crops require a bit of planning, but are absolutely worth your time in the garden. Cover crops are typically grown following the final harvest in the fall and throughout the winter. Some emerge in the early spring before you plant.
Ideally, you should paint your cover crops wherever you intend to garden next year. The crops can help improve the ability of the soil and also improve its overall structure. This can reduce issues like erosion, compaction, and run-off. Not only that, buying cover crops can suppress weeds so you don’t have to worry about tiling, either.
When it comes to removing the cover crops so you can plant, all you need to do is chop them down. You can mow them in or turn them under, too, but this will cause more compaction.
22. Quit using chemicals
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The best tip I can give you when it comes to improving the soil fertility of your garden? Stop using chemicals.
While there are times you may feel tempted to use chemicals to get rid of severe pest infestations or treat severe soil deficiencies, in almost all cases, these applications can be prevented. By being proactive and paying attention to the unique biology of your soil, you can improve its ability, and reduce your reliance on chemicals that are not only good for the soil, but not good for you, either.
Give all of these natural fertilizers a try, or just give one or two a go. Whatever you choose, your garden will thank you. After all, the best way to improve the fertility of your garden is to do it slowly, gradually, and over a long period of time.
That way, you can enjoy a bountiful harvest for years to come, not just for the next few weeks – like you might when you use quick-fix synthetic fertilizers!
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