Question
i am a student who is doing a science project on if manure is a good fertilizer or not. Do you think manure is a better fertilizer than regular fertilizer or not? Why?

Answer
Boy have YOU come to the right place for a question like that!

Do I have an opinion on this?  You betcha!

First, let's consider something that ads don't mention, and people forget: Plants are AUTOTROPHS. They make their own food. They make their own energy (out of air, water and sunlight - photosynthesis, as you know). They DO NOT NEED food!

So the concept of feeding plants is really a misconception.

I know, I know.  You did not say this.  But remember, this is what people think.  And that's why they call it "plant food".  So we have to keep this in mind.  Because it is very basic to your question, and it is an important foundation for my answer.

Why do plants need fertilizer, anyway?  Giving a plant, say, Nitrogen is not like giving me a hamburger.  In fact, I have to eat that hamburger, and the cow that became the hamburger had to eat... PLANTS.  All our energy up and down the food chain depends on autotrophic plants for survival.  And plants depend on sunlight.  You can't feed a plant.  It needs sunlight.

But most people have a very hard time with this concept.  They insist on viewing that Nitrogen, or Phosphorus, or Potassium as "food".  And just like they open a bag of dog food to feed the family dog, they open a bag of fertilizer and "feed" their plants.

Plant leaves capture sunlight, and combine it in a very sophisticated way with H2O (water) and CO2 (air).  When the chemical reaction is finished, the plant has energy, and it stores the energy as Carbon-based carbohydrates.  We need those carbohydrates.  We can't get them any other way.

100 years ago, someone figured out that plants need 3 molecules more than any other: Nitrogen, Phosphorus, and Potassium. N, P, and K.  Since these minerals were so important, they called them MACRO nutrients.

There were also MICRO nutrients, but much smaller amounts were needed.

Later we learned that there are some nutrient minerals that you need just in tiny tiny tiny amounts.  They call these TRACE nutrients. They're necessary, but only a handful of molecules are needed of Trace nutrients.

If plants make their own food, why do they need nutrient minerals at all?

Not to make ENERGY.

They need those nutrients to run the business.  Figure, if you put gas in a car, it's not going to run itself, right?  You've got to put someone in the driver's seat and have them drive it.  When it rains, the windshield wipers have to work.  The car is running on gas, but if there's no one behind the wheel, or if the battery is dead, or if you get a flat tire, the car won't go anyplace.

So it is with plants.

They make their own energy.  But someone's got to put together the little solar labs that work all day long making that energy.  A plant needs to make Chlorophyll.  It needs to grow a longer stem.  It has to produce flowers, and grow and repair roots.  It needs equipment.

And it builds that equipment out of N, P and K.  Plus micronutrients, and some trace elements.

When you put fertilizer on a plant, which the fertilizer companies want you to do because it will make them rich, you are pouring dissolved minerals into the soil and expecting that they will be soaked up by the plant.

However, when you put Manure in the soil that the plant is growing in, the plant gets nothing.  Because the minerals are not dissolved.  Instead, microbes find the manure and they are very happy about that.  They finish off that manure like some people finish off a roast beef sandwich.  Microbes -- good microbes -- decompose the manure and replace it with minerals.  This goes on for as long as it can, typically years.

It sounds like the fertilizer is better.  It's faster, and it's pure nutrients.

But nothing could be farther from the truth.

Because remember, we are not giving those plants FOOD.  These minerals are needed for growth.  Not for energy.  So if you put fertilizer on the plant, and the plant takes just a little bit, the rest is washed away with the rain.

But when you put Manure down instead, the Manure is there FOR YEARS.

Most Nitrogen fertilizer is gone within HOURS of being put down on a Lawn.  And all Nitrogen fertilizer is is Nitrogen.  If you have a "balanced" fertilizer, you have N, plus Phosphorus and Potassium, too.  But these are also gone very quickly.  And the plant is left standing without equipment.

Manure contains N, P and K plus trace minerals and micronutrients.

There's more.  Earthworms are quite content to congregate in an environment that surrounds them with Manure.  Sounds creepy, doesn't it?

But if you put Earthworms in a container of soil and pour fertilizer on it, the Earthworms go into shock.  Those fertilizers are not popular at all with the Earthworm population.  And we love Earthworms, because they make their own nutrient-rich castings that keep fertilizing as long as that Earthworm is around.

A little more chemistry here, just for your edification.  Fertilizer in a bag is chemically unable to stick to soil particles.  That is why the minerals in the fertilizer flow right through.  The atoms repel.

Manure-based nutrients, however, need no special treatment.  Their NPK sticks to soil and waits patiently until it is time to move up the roots and flow into big, green leaves.  In the summer, when the temperature gets higher, the bacteria down in the ground pick up the pace and send more minerals.  In cool weather, the bacteria slow down and if needed grind to a holt.  No fertilizer can do that.

What you might consider instead of Manure, however, is compost tea.  This liquid essentially does the same thing as Manure, but in liquid form.

Any questions?

THE LONG ISLAND GARDENER