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| Illustration/Elayne Sears |
By Barbara Pleasant for Mother Earth News
Homemade liquid fertilizers made from free, natural
ingredients — such as grass clippings, seaweed, chicken manure and human
urine — can give your plants the quick boost of nutrients they need to
grow stronger and be more productive.
Many organic gardeners keep a bottle of liquid fish
fertilizer on hand to feed young seedlings, plants growing in containers
and any garden crop that needs a nutrient boost. But liquid, fish-based
fertilizers are often pricey, plus we’re supporting an unsustainable
fishing industry by buying them. So, what’s a good alternative?
MOTHER EARTH NEWS commissioned Will Brinton — who holds a
doctorate in Environmental Science and is president of Woods End
Laboratories in Mt. Vernon, Maine — to develop some water-based,
homemade fertilizer recipes using free, natural ingredients, such as
grass clippings, seaweed, chicken manure and human urine. His results
are summarized on our chart of
Homemade Fertilizer Tea Recipes.
Why and When to Use Liquids
Liquid
fertilizers are faster-acting than seed meals and other solid organic
products, so liquids are your best choice for several purposes. As soon
as seedlings have used up the nutrients provided by the sprouted seeds,
they benefit from small amounts of fertilizer. This is especially true
if you’re using a soil-less seed starting mix (such as a peat-based
mix), which helps prevent damping-off but provides a scant supply of
nutrients. Seedlings don’t need much in the way of nutrients, but if
they noticeably darken in color after you feed them with a liquid
fertilizer, that’s evidence they had a need that has been satisfied.
Liquid fertilizers are also essential to success with container-grown
plants, which depend entirely on their growers for moisture and
nutrients. Container-grown plants do best with frequent light feedings
of liquid fertilizers, which are immediately distributed throughout the
constricted growing area of the containers.
Out in the garden,
liquid fertilizers can be invaluable if you’re growing cold-tolerant
crops that start growing when soil temperatures are low for example,
overwintered spinach or strawberries coaxed into early growth beneath
row covers. Nitrogen held in the soil is difficult for plants to take up
until soil temperatures rise above 50 degrees Fahrenheit or so, meaning
plants can experience a slow start because of a temporary nutrient
deficit in late winter and early spring. The more you push the spring
season by using cloches and row covers to grow early crops of lettuce,
broccoli or cabbage in cold soil, the more it will be worth your time to
use liquid fertilizers to provide a boost until the soil warms up.
Water-soluble homemade fertilizers are short-acting but should be
applied no more than every two weeks, usually as a thorough soaking.
Because they are short-acting, liquid fertilizers are easier to regulate
compared with longer-acting dry organic fertilizers, though I like
using both. With an abundant supply of liquid fertilizer to use as
backup, you can use a light hand when mixing solid organic fertilizer
into the soil prior to planting.
Remember: If you mix too much nitrogen-rich fertilizer
into the soil, you can’t take it back. As soil temperatures rise, more
and more nitrogen will be released, and you can end up with monstrous
plants that don’t produce well. In comparison, you can apply your
short-acting liquid fertilizers just when plants need them — sweet corn
in full silk, peppers loaded with green fruits — with little risk of
overdoing it. Late in the season, liquid fertilizers are ideal for
rejuvenating long-living plants, such as chard and tomatoes, which will
often make a dramatic comeback if given a couple of drenchings.
Making Your Own
To
explore the art of making fertilizer tea, Brinton began by trying
various ways to mix and steep grass clippings, seaweed and dried chicken
manure (roughly 33 percent manure mixed with 66 percent wood shavings).
The best procedure he found was to mix materials with water at the
ratios shown in the
Homemade Fertilizer Tea Recipes chart, and allow the teas to sit for three days at room temperature, giving them a good shake or stir once a day.
“By
the third day, most of the soluble nutrients will have oozed out into
the water solution,” Brinton says. Stopping at three days also prevents
fermentation, which you want to avoid. Fermented materials will smell
bad, and their pH can change rapidly, so it’s important to stick with
three-day mixtures and then use them within a day or two. Brinton also
studied human urine, which is much more concentrated than grass, manure
or seaweed teas, and doesn’t need to be steeped.
The lab analyzed
the four extracts for nutrient and salt content. Salts are present in
most fertilizers, but an excess of salts can damage soil and plant
roots. Brinton found that chloride and sodium salts were so high in
urine that they needed to be diluted with water at a 20:1 ratio before
being used on plants. In comparison, the seaweed extract could be used
straight, and the grass clipping and chicken manure extracts needed only
a 1:1 dilution with water to become plant-worthy. Read the
full report from Woods End Laboratories.
As a general guideline, most vegetables use the three major plant
nutrients — nitrogen, phosphorus and potassium — in a ratio of roughly
3-1-2: three parts nitrogen, one part phosphorus and two parts
potassium. This means that an N-P-K ratio of 3-1-2 is more “balanced” in
meeting plants’ needs than 1-1-1, the ratio many gardeners assume is
best. Because liquid fertilizers are a short-term, supplemental nutrient
supply secondary to the riches released by organic matter and microbes,
they don’t need to be precisely balanced. The teas made from grass
clippings and urine come closest to providing the optimum 3-1-2 ratio.
Nitrogen helps plants grow new stems and leaves.
Phosphorus is essential for vigorous rooting, and is usually in good
supply in organically enriched soils. Potassium is the “buzz” nutrient
that energizes plants’ pumping mechanisms, orchestrating the opening and
closing of leaf stomata and regulating water distribution among cells.
The grass clipping and poultry manure teas are rich in potassium, which
should make for sturdy plants with strong stems when used to feed young
seedlings. Blending some grass or manure tea with a little nitrogen-rich
urine would give you a fertilizer to promote strong growth in
established plants. I like to add a few handfuls of stinging nettles,
comfrey, lamb’s-quarters or other available weeds to various mixtures,
which probably helps raise the micronutrient content of my homemade
concoctions in addition to providing plenty of potassium.
On the
practical end of liquid-fertilizer making, you may need to use a
colander to remove some of the grass clippings before you can pour off
the extract. If you haven’t completely used a batch of fertilizer within
two or three days, pour it out beneath perennials or dump it into your
composter.
It’s important to relieve drought stress before doling
out liquid fertilizer. Watering before you fertilize helps protect
plants from taking up too many salts. Also keep in mind that continuous
evaporation in containers favors the buildup of salts. By midsummer, a
patio pot planted with petunias or herbs that are regularly fed with any
liquid fertilizer may show a white crust of accumulated salts inside
the rim. Several thorough drenchings with water will wash these away,
making it safe to continue feeding the plants with liquid fertilizers.
There is no doubt human urine can be a valuable fertilizer for garden
plants. The average adult produces about 1 1/2 quarts of urine per day.
Diluted 1:20 with water, this would make about 7 gallons of
high-nitrogen liquid fertilizer, so a family of four could produce
enough high-nitrogen fertilizer for an average garden and lawn. As
Brinton suggests, when we think of N-P-K, we should also think N-Pee-OK!
You can make your own liquid soap using scraps from your favorite bar soap....
Maybe it’s all the diapers I’ve changed, but I don’t like
minding pails of pee. In winter at my house, we have a bucket of
sawdust stationed on the deck to help us capture this valuable resource,
and we keep a designated bale of hay out in the garden for urine
deposits. If you do the same, you can use the urine-enriched sawdust and
the hay from “pee bales” as nutrient-rich mulches in your garden.
Whatever
materials and methods you choose, you’ll be pleasantly surprised by the
simplicity of making your own no-cost liquid fertilizers.
Longtime MOTHER EARTH NEWS contributing editor Barbara Pleasant provides authoritative reporting on topics essential to helping you grow your own food as sustainably as possible.
