Hey Gardenerds, I'm Christy Wilhelmi. Today I want to address another question that has
come across my desk a number of times and that is, "What's the difference between compost
and fertilizer?" So let's break it down. First up, a refresher on compost because I did another video
on the difference between compost and mulch which you can check out that really goes into depth
about what compost is. When it comes to fertilizer some people do use compost as a fertilizer, but
the truth is compost is kind of a low-level nitrogen fertilizer. It doesn't have a whole lot of
nutrients in it. It is mostly soil biology, if it's healthy compost. If it's been baking out in the sun
pretty much all the microbes are dead, but if it's healthy and it's been kept, you know, moist
and in a shady spot, it's going to be viable and that's pretty much going to inoculate your soil
when you apply it with beneficial microbes and undecomposed organic matter whatever remains in
the compost to help increase porosity and airflow through the soil. So that is what compost does.
It also has a few other things going on for it but I want to focus on fertilizer today so
you know the difference between the two. First off, let's talk about those numbers on the box. So
I have here a box of fertilizer. This is for veggie gardens and you'll see these
three numbers: four, four, four. Now on some things, like blends for fruit trees, for example, you'll see
six-two-four. What do these numbers mean? Well, this is always in the same order and it always
means the same thing. The first number represents nitrogen, the second number represents phosphorus,
and the third number represents potassium. So those numbers on the periodic table are N, P, and K. And
the K throws people off because it's potassium. Anyway, these, uh, numbers represent the percentage
of each of those elements in relationship to the other element the other elements in here and
on the box. So most of the time in synthetic fertilizers you're going to pick up the box
and the numbers on the back will be quite high. It'll be you know 10, 20, 30, up there.
These synthetic nutrients are synthesized usually through what's called the Haber-
Bosch process or the Haber-Bosch process. You can look that up, I'm not going to go into it here.
But basically that is how synthetic nitrates are created. But when you read the back of the box it's
all going to be derived from chemical signatures. So that's not something that I encourage people
to use. I'd rather you pick up a box of fertilizer that is OMRI certified or USDA organic certified
or CCOF certified. These are all institutions that label something as being safe for use in organic
agriculture. On the back of a box of organic fertilizer you will see things you actually
recognize like blood meal, bone meal, feather meal, calcium carbonate, which is, you know, that's pretty
straightforward. It's calcium. Languinite, these are mined minerals, alfalfa meal,
kelp meal, and potassium sulfate. Now let's pause and talk about what each of these numbers do.
So nitrogen, nitrogen is responsible for green leafy growth. That's my little hand signal when
I teach the class so that people can physically anchor what nitrogen does.
Phosphorus and potassium, they work together and depending on which country you live in you'll see
them attributed to different things. Here in the US, you'll see that phosphorus is attributed to
root development. But if you look over across the ocean in the UK it's also attributed to fruiting
and flowering, which is important because if you're growing anything in your vegetable
garden that makes a fruit, that phosphorus is going to be one of the most important things.
The third number on the box is potassium and potassium is responsible for overall vigor
as well as fruiting and flowering. You can use this information to diagnose what's going on
with your plants and what maybe your soil needs. These nutrients of course I call the Big Three.
Nitrogen, phosphorus, potassium. Those are the Big Three. But there are also usually some minerals
in the in the mix as well that naturally come from some of the other ingredients. The thing you
need to know is that it's really important to take a soil test before you apply any kind of
fertilizer to your garden. Simple soil tests that test nitrogen, phosphorus, potassium, and soil pH
are available online or at your local nursery. It takes a few minutes to take a soil sample
let the soil, you know, you put it in water, let the soil settle overnight. If you have clay soil
it can take it can happen really quickly. If you have sandy soil it can take longer. And then you
draw off some water, you put it in the little pipette, you know, in a pipette and you drip it
into the test kit. Put in the capsule, shake it up, set it on the counter. Really fun to do with kids,
by the way. I'm not a kid, I don't have any kids but, you know, really fun to do if you are a kid or feel
like a kid on the inside. Anyway. Take the soil test see what's lacking and then amend based on that.
Really important not to over fertilize because that can cause imbalances in the soil. It can send
microbes packing, it can kill off some others. But generally speaking synthetic fertilizers can cause
problems in soils and end up in the water table which causes algae blooms out in the ocean. Because
nitrates, remember nitrates, create green leafy growth. That includes algae and that algae steals
oxygen from the fish, and then we create these dead zones out there. So the lower levels of
nutrients that you find in organic fertilizers are better suited to gardening, because it's
actually more at a level that the plant can absorb and the less of it washes away. Now I
want to address something for a minute. For those of you who have been following me for a while,
it is the belief of the people I have learned from, particularly Dr. Elaine Ingham, that soils...
every soil has exactly what it needs to grow without the need for any fertilizers.
And that is most likely true. I have found with my sandy soil I have to add a little bit of something.
Because the soils even with high biology in the soil there's still the nutrients just
flush out really quickly. So I add just a pinch of fertilizer in the bottom of the planting hole
of my heavy feeder crops like tomatoes and peppers and eggplant. I put a little bit at the bottom of
these these kale plants here. They don't need much but I just wanted to give them a little something.
The best thing you can do is amend your soil with really good compost and worm castings,
of course, because they have a lot of low level nutrients that boost compost even more and make
nutrients available to plants. Because the microbes consume those low-level minerals
that worm castings provide. Also it's important to distinguish the difference between compost
and fertilizer in this way. Compost is something that is usually fabricated from animal manures
and biomass: browns and greens. But fertilizer is usually processed from animal
byproducts meaning blood, bone, feather, and other things like cottonseed meal, alfalfa meal, soybean
meal and that kind of stuff with a few minerals thrown in there for good measure. You can also
make compost yourself whereas fertilizer you would need to buy the components and mix your own blend.
I try to avoid using fertilizers as much as possible but sometimes you just need it.
So use it with caution, use it after testing, and make sure it's what your soil and plants need.
So take this information out into your garden and put its good use. If you like this video
share it with your friends and don't forget to subscribe and turn on notifications so
you'll find out when our next video comes online. Consider becoming a Patreon subscriber to support
all the free stuff that we do here at Gardenerd. And of course you'll find tons of information
like this in my books Gardening for Geeks and Grow Your Own Mini Fruit Garden. Happy Gardening!