It can be difficult to grow vegetables and other plants if your soil is lacking in vital nutrients.
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.
Here are some of the easiest ways to improve the nutrient content of your soil – most of which are free or low-cost.
What Soil Fertility Is, and How to Tell If Your Soil is Fertile
In short, fertile soil is healthy soil. Your plants need vitamins and minerals just like people do!
Fertile soil will have all the nutrients necessary for plants to grow and thrive.
The manufacturers of synthetic fertilizers would have you believe that this means your plants only need nitrogen, potassium, and phosphorous, but there all kinds of micronutrients they need too, including calcium, copper, and magnesium.
Soil fertility goes beyond just the nutrients, though, too. 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 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
Before you engage in 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 is remaining fertile and balanced.
Making Soil Fertile
1. Fix the Texture First
Check the texture of your soil before you work to amend it. While loam soil 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
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.
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.
Horse manure is a popular choice, especially if it was from a horse bedded on straw. You can often use cow manure, too.
Chicken manure can be added to the garden, but you’ll want to let it compost first as the high level of nitrogen can burn the soil. There are some microbes in the soil that can cause illness, too, if they haven’t had enough time to break down.
If you have access to goat, sheep, or rabbit manure, that’s even better. These manures are small pellets that do not need to be composted. They produce minimal odor and mess, and are easy to apply to the garden. They can even be added as a top-dressing!
You should avoid manures from household pets, like cats and dogs, along with humans, of course.
Good ol’ fashioned compost – this is usually 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.
5. Compost Tea
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, that can be used throughout the entire planting season.
6. Fish manure
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.
7. Alfalfa Meal
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.
8. Leaf Litter
Autumn leaves are a great source of carbon and other nutrients for your garden. They can be used as mulch or included in a compost. 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.
You can also use leaf and plant waste compost, which can be made at home with these simple ingredients.
9. Soybean Meal
Soybean meal contains lots of nitrogen along with balanced amounts of potassium and phosphorus. It can be expensive, but is a great source of natural nutrients for your garden.
Save the ash from your fireplace – as long as you did not use wood that was treated with any chemicals – and you can use it in your garden. It will add potassium as well as calcium.
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.
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.
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, 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, do so at a later of two to three inches thick. Keep about an inch away from the base of your plants to prevent rot.
14. Tea leaves
Tea leaves are an excellent source of nitrogen for the garden! You can use them in the compost or when you plant.
15. Blood meal
It sounds a bit unsavory, but don’t be afraid to get a bit bloody in the garden. 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.
16. Coffee grounds
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.
17. Banana peels
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 in the garden.
All you need to do is bury your peels and they will add potassium back to the soil. You can do this when you plant or long before, too.
18. Bat guano
You likely won’t be able to make or harvest your own bat guano at home – in fact, I don’t recommend it. However, you can buy inexpensive bat guano that contains tons of nutrients that your garden needs to be healthy.
To name a few, bat guano contains nitrogen, phosphorous, and other macronutrients. It is water-soluble, so it is readily available to your plants.
It will provide everything your plants need for vegetative growth as well as for fruit and flower development. Plus, it can be applied as a tea, foliar spray, or even as a top dressing.
19. Sodium / Chilean nitrate
Sodium nitrate and Chilean nitrate are two fertilizers that act like synthetic fertilizers, yet are approved for organic gardeners.
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.
20. Feather meal
A common byproduct of chicken or poultry processing, feather meal contains high levels of nitrogen – up to 10%.
It breaks down a bit more slowly than other types of nitrogen-based fertilizers, but this can often be advantageous. If you raise chickens, it’s a cost-effective way to fertilize the garden.
21. Bone meal
Bone meal is a fantastic source of phosphate for the garden. It contains about 27% total phosphate, most of which can be readily absorbed by the oil in your garden.
You can purchase bone meal, or you can make your own by saving and then grinding down the bones when you butcher chickens or other livestock on your farm.
22. Kelp meal
Kelp meal is another option that can be added to the soil. Unless you live near the ocean, however, kelp meals can be quite expensive.
It adds a healthy dose of nitrogen when in need, though. Kelp meal can be applied directly to the soil, and integrates well with it.
23. Get those chickens going
The chicken is Mother Nature’s favorite gardening companion!
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 with zero damage, 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.
24. Fish emulsion
Fish emulsion, also known as fish meal, is another great way of improving soil fertility. You need to be careful about where you get your fish meal from – it’s not always considered organic, as there may be additives.
You can make your own with ground-up fish and fish bones, though, too.
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.
26. Implement lasagna gardening
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.
27. Mineral phosphate
You might also consider adding mineral phosphate to the soil. There are three major types – colloidal, soft rock, and hard rock.
Hard rock phosphate comes from volcanic deposits, while soft rock originated mostly from ancient sea deposits. Colloidal phosphate is from clay.
Clay phosphates are the easiest to find, while hard rock are the most difficult. These are commercial products that are made by combining rock phosphate with acids.
They aren’t as effective as some of the other phosphorus-rich fertilizers on this list – like bone meal – and can be high in heavy metals. Use these sparingly!
28. Potassium sulfate
Potassium sulfate, along with potassium magnesium sulfate, are considered partially synthetic and partially organic.
They are allowed by organic farmers but only if you use a mined source that has never been treated with acid or other chemicals. It works quickly, but it can be quite harsh. It builds fertility momentarily but it won’t last between seasons.
29. Worm castings
If you have a vermicomposting system at home, you should save the worm castings and apply them to your garden.
They’re totally organic, yet 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.
30. Quit tilling
Tilling has its benefits, sure. It loosens up the soil so you can get to planting and mixes weeds into it. It’s the easiest way to break up the soil when you’re ready to plant.
However, if you can dedicate some time to planning out your garden ahead of time, tilling may not be necessary.
Tilling, in fact, can be quite disadvantageous when it comes to the fertility of your soil. Not only can it disrupt the natural processes of the soil, but it can kill your fertility, too.
It disrupts natural bacteria and removes air pockets, making it difficult for helpful bacteria, worms, and other beneficial insects to survive, and it even stirs up weed seeds.
Instead, use alternatives to tilling (like broad forks, cover crops, and weed-killing plastic) to get your garden ready to go in the spring.
Gypsum is a great source of both sulfur and calcium.
Lime not only adds calcium, it also helps moderate the soil pH if this is an issue for you.
If you use lime or gypsum, make sure it is naturally mined, and not the product of industrial waste. These are also sold, but are definitely not good for your garden.
33. Basalt dust
Basalt dust can offer a variety of trace minerals. It can be somewhat expensive, but is especially helpful when mixed with manure. It breaks down slowly, over a period of several years, so it won’t overwhelm your garden.
Glauconite is a slow-release option for your garden. It is a mineral that allows potash to be released in a balanced, gentle way.
It can be quite expensive, though, so keep this in mind. Glauconite is sometimes also sold as greensand.
35. Granite dust
Granite dust also releases quite slowly. It is a good source of potassium. However, it does not break down completely in the soil. It’s often sold as a “slowly available” ingredient for organic farms.
36. Try using a broad fork
Instead of tilling to break up the soil in your garden, consider using a broad fork. Broad forks open up the soil in a gentler way, creating aeration instead of destroying it.
37. Bury compost
It might seem foolhardy to bury compost, but really, it’s a great way to increase your soil fertility. You will need to dig a trench and fill it in with all kinds of compost ingredients.
Cover it, and it will serve as an underground compost that will feed your soil all year long. Plus, you won’t have the inconvenience or eyesore of a compost pile hanging out in the corner of your yard!
38. Utilize plants’ taproots
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.
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.
39. Use cover crops
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.
40. Quit using chemicals
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!