For Soil :: Negative Effects of Urea in Soil

Urea is used as a nitrogen release fertilizer as it hydrolyses back to 2NH2 and CO2 but its most common impurity (biuret,NH2-CO-NH-CO-NH2) must be present at less than 2% as it impairs plant growth. It is also used in many multi-component solid fertilizer formulations.
Its action of nitrogen release is due to the conditions favoring the reagent side of the equilibriums which produce urea.

Andy Lopez from "The Invisible Gardener" wrote this about Urea:

Brief History
H.M. Rouelle in 1773 discovered Urea in human urine. It was synthesized in 1828 by Friedrich Wohler.This is when Wohler wrote to Berzelius the following: “I must tell you that I can make urea without the use of kidneys, either man or dog. Ammonium cyanate is urea!” This synthesis has since then been trying to deal a severe blow to the belief called “vitalism” which maintains that organic chemicals can be modified by chemistry but could only be produced through the agency of a vital force present in living plants and animals. Here is where the organic gardener and the chemical gardener part ways. Those of you that believe in this vitalism in general stand to the right and those of you that say there’s no difference stand to the left! In 1870 urea was produced by heating ammonium carbamate in a sealed vessel. This provided the basis of the current industrial process for its production.

Urea is produced commercially by the dehydration of ammonium carbamate (NH2COONH4) at elevated temperature and pressure. Ammonium carbamate is obtained by direct reaction of ammonia with carbon dioxide. These reactions are normally carried out simultaneously in a high pressure reactor.

There are many uses for urea: Pharmaceutical, Resins, Agricultural, as well as Industrial uses; for our purpose we will stick to its agricultural uses and the effects it has on the soil, plants, lawns, trees, etc.

Nitrogen is nitrogen is nitrogen?
The whole idea is that there is a difference between an organic source of nitrogen and a chemical source of nitrogen. Urea (when it was discovered that it could be made from inorganic ( non-living) compounds and that chemically it was identical to its natural cousin Urine) was proclaimed as an important tool in growing more food to help feed the worlds growing population. This is still the current logic that chemical companies would like you to believe. The American idea that a little is OK but a lot is better does not really apply here.

Urea is 45% nitrogen and 55% inert. Animal urine is closer to 2-5% nitrogen along with a variety of minerals and bacteria. While I admit that nowadays it is easier to get Urea then it is to get animal urine, animal urine is the preferred organic method of nitrogen application. Another good reason most people do not use animal or human urine is health concerns although animal or human urine is perfectly safe to use as long as the donor is healthy. I use animal urine whenever I can and admit that it is harder to get at then its chemical cousin since you have to have access to a farm and make arrangements to have it saved for you as well as to find out if any chemicals have been injected into the animals, etc.. While it is understandable why we use Urea as a urine substitute the negatives far out weigh the positives.

Positives and Negatives about Urea

Sorry but I can’t think of any thing positive about using Urea except it makes money for anyone selling it!

1- Rapid Growth pushes plants to grow too fast
2- Plants grow fast but are very weak
3- Promotes stress
4- Destroys soil organisms
5- Increases pest activities
6- Increases disease activities
7- Urea breaks down into various compounds some of which can inhibit plant growth.
8- Eventually decreases plant production
9- Decreases nutritional values of plants to humans while increases nutritional value to pests.
10-The carbon in Urea based fertilizers is chemically converted to CO2 and lost to the atmosphere. Carbon is energy to plants and soil micro-organisms.

More is better?
It is a mistaken idea that more nitrogen is better then less. What you must understand is how nitrogen is available in nature and how plants and soil organisms use it. Nitrogen is produced freely in nature by various mechanisms found in nature. The most obvious sources of nitrogen is animal manure. Another source is bacterial action. The bacteria produce nitrogen in a form available to the root hairs (through which it is absorbed into the plants) as well as a variety of other nutritional sources. Another source (actually #1) is produced by nature herself through the various storms she has on the planet.

Why Urea causes stress?
Plants can absorb nitrogen directly from the air as well as from the soil but they can also absorb it directly through their leaves. A basic problem with Urea based products is how it is available to plants. Natural sources provide plants with nitrogen as they need it and when they want it as opposed to chemical nitrogen such as Urea which is absorbed by the plants in very large amounts whether it needs it or not. This is where stress comes in. By force feeding your plants this chemical nitrogen, you are causing stress in the plants. Stress is also caused by the fact that Urea kills off all beneficial soil bacteria which are needed to breakdown the nutrients needed by plants. As the soil becomes less and less alive, the plants become increasingly dependent on the straight shots of ‘food’ it gets from the chemical fertilizer you are using.

How you feed your plants is as important as what you feed them?

Some Factors that cause stress in plants:
1..dead soil
2..low nutrition levels
3..low mineral levels
4..planted in wrong environment
5..wrong variety planted
6..other chemical use such as herbicides, pesticides, etc.

What Urea does to the soil:
There are two ways to sterilize the soil, using chemicals and using heat. Urea is a chemical that sterilizes the soil by killing off all the good bacteria normally found living in the soil. Urea because of its identical molecular structure is mistaken by bacteria and plants as a food source. Because Urea is a much more concentrated source of nitrogen, the bacteria are not fed but are actually destroyed leaving behind a mutated form of bacteria which the plants cannot use. Slowly plants find themselves weakening, starving from lack of proper nutritionist and stressed out. Their root systems no longer function as they should. They depend more & more on their chemical ‘hit’ to provide nutrition for them. The soils natural bacterial system is converted into one that cannot be used by plants root systems for food absorption but instead the bad bacteria themselves begin to feed off the plants!

What Urea does to the Plants:
The plants get an immediate ‘relief’ when you apply or spray fertilizers based on urea or some other chemical form of high nitrogen, but as it wears off the plants return to their weakened state and become even more stressed. This process is repeated over and over again. Less soil bacterium less root hair which equal less food being absorbed by the plants which means less energy, less minerals, more stress. Many chemical fertilizers are now using timed release fertilizers that release their ‘hits’ over a time, thus reducing down time. However this is not the case at all, instead the timed release fertilizers merely are increasing stress. Now Plants are stressed out all of the time! Fertilizer companies are also adding more nutrients to their Urea based fertilizers to help plants last longer as well as systemic to fight off pests and diseases. Plants thus stressed out are more inclined to disease and pest attacks then organically grown plants.

What Urea does to Diseases:
The very same bacteria that are normally present in the soil dies and is replaced by a different type of bacteria. Some of the bacteria are of the “bad” type. This is to say the bacteria are of the fungal disease type and are all soil born. They can establish themselves in the soil if certain conditions are right for them. The main condition being the lack of the “good” bacteria.

The Good Guys and The Bad Guys do not live in the same place!
What are the perfect conditions for diseases to occur?

Dead Soil Chemical over use destroys all soil bacteria expect for a few specific types of bad bacteria that depend on these conditions to grow. Urea when used over many years, destroys this balance of good and bad bacteria.
Stressed Plants Dead soil increases the plant's stress levels due to bad conditions for plant growth.
High Nitrogen High nitrogen causes rapid growth. Rapid growth without proper nutrition causes more stress which in turn restricts more nutrition from being absorbed by plants. High nitrogen also attracts insects that have mutated to handle plants that have such rapid growth. High nitrogen also mutates bacteria into rapid growth cycles.
Environmental stress can be from improper watering to weather cycles such as too much rain or drought. Biological considerations. Planting the wrong variety or type of plant in the wrong environment will certainly cause major stress to plants and all involved.
Over Chemical use of any type from pesticides to herbicides, etc. will cause major damage to soil's Eco system and disrupt nutritional levels.

The Ole Barrel Trick! (The Law of the Minimum)
If you were to look at a wine barrel. Notice how the slots are held together by a band going around it with a bottom to hold the liquid. Imagine that each slot of the wine barrel was a element needed by plants. Starting with nitrogen, potassium, phosphorus and so on. Now lets say they were to actually represent the amount that was available to plants to use. the greater the length the more is available. The nitrogen ‘slot’ is 1 foot up above the top level of the wine barrel with various lengths of ‘slots’ for the varying amounts of each. Now lets suppose we started filling it up with water. How far up the barrel could we go before water would start spilling out? The lowest slot of course! All that nitrogen above the lowest slot is useless in holding any water isn't’ it? Actually all the nitrogen is what cause some of the other slots to be so low. remembering that there is a basic minimum level of minerals that you want. Too much minerals become toxic to its environment as too much nitrogen becomes toxic to its environment.

What now?
Feed the bacteria first and let the bacteria feed the plants.
Use slow release organic sources of nitrogen only.
Never use Nitrogen sources only but combine with minerals and bacteria.
Provide minerals in amounts needed by soil and plants.
Encourage high bacterial count by increasing use of compost based products or make your own compost.

Remember: High Nitrogen=High Stress=Disease/Pests=Low Minerals=Low Nutrient levels=Low Energy, High Energy=High Nutrient Levels=No Stress=No Pests/ Diseases!

One final note: There is a reason why Certified Organic Farmers cannot use store bought Urea based products! I am only talking about man made urea and not that naturally made by animals including humans. Please don't allow people to convince you that there is no difference between the two and it is therefore ok to use it. Tell the plants, the soil that!

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