what is urea fertilizer

Chemical and Organic Nitrogen fertilizer in Soil

Chemical Sources Of Nitrogen In Soil.

Plant Fertilization

Ammonia (liquid ammonia): This is perhaps the most widely used of all nitrogen fertilizers today, yet is of no practical value to the home gardener who needs more nitrogen in soil, because special apparatus is needed to apply it. It is mentioned here only because many gardeners ask about it after reading accounts of its use in agriculture. These liquids run about 30 percent ammonia, of which about 85 percent is nitrogen.

What is ammonia nitrogen

Ammo-Phos (ammonium phosphate): There are two commercial grades of this material. Grade A contains 11 percent nitrogen and 48 percent available phosphoric acid. Grade B contains 16 percent nitrogen and 20 percent phosphoric acid. Both are excellent sources of completely soluble nitrogen and phosphorus.

Ammonium Phosphate Fertilizer: There are two grades: monoammonium phosphate contains 11 percent nitrogen and 60 percent phosphoric acid while diammonium phosphate analyzes at 23 percent nitrogen and 53 percent phosphoric acid. Both are completely soluble. Beware of using them on rhododendrons and other acid-loving plants, however, as they are quite alkaline in reaction.

Ammonium Sulfate (sulfate of ammonia): Once the leading source of nitrogen in chemical fertilizers, it is still #1 for getting more nitrogen in soil on the home gardener’s list. In the agricultural field, its place is being taken over by liquid ammonia. The sulfate of ammonia contains about 20 percent nitrogen. It can be applied dry but must be watered in immediately to avoid burning. It is much safer if first dissolved in water.

Sodium Nitrate fertilizer (nitrate of soda): This was one of the first chemicals used as a fertilizer. Vast deposits of sodium, combined with oxygen and nitrogen, were found in Chile and were worked for fertilizer purposes during the nineteenth century. Because it was for many years the leading source of chemical nitrogen, it is firmly entrenched in the literature of gardening. It is often recommended out of habit when other materials would be safer and better for more nitrogen in the soil. Sodium nitrate may have some use in strongly acid soils but will deflocculate clays and make them greasy if used too often. It is not an ideal source of nitrogen and other materials should be substituted if possible.

Sodium nitrate fertilizer

Urea: Discovered originally in urine, this is now produced synthetically in large quantities. Urea is not a protein but because it contains a carbon particle, it is classed as an organic compound, to the consternation of organocultists. While not instantly available, urea goes through fewer stages to break down into nitrate form, hence starts feeding a little more rapidly than do organic products.

what is urea fertilizer

Ureaform: This is a most unusual fertilizer material – it is best described as a nitrogen-bearing soft plastic material that breaks down slowly but uniformly when in contact with soil organisms and moisture. It is made by reacting urea and formaldehyde. It contains 38 percent nitrogen, yet can be applied to grass without fear of burning. This is because ureaform gives off nitrogen so slowly that grass can absorb it about as fast as it is released. Enormous quantities have to be applied before a burn can be produced. Ureaforms combine the best features of chemical and organic plant foods. Their one drawback is the slowness with which they begin to feed.

Organic Nitrogen In Soil

Castor Putnace

This is the refuse left after castor beans are processed for oil. It cannot be used for cattle feed because it is poisonous to animals (but not to plants).

It contains about 5.5 percent organic nitrogen. Traces of both phosphorus and potash make it a fair fertilizer, particularly on acid-loving plants.

Cottonseed Meal

Also used as a fertilizer for acid-soil plants, it contains about 6 to 7 percent nitrogen, 2 percent phosphorus and 2 percent potash.

Since it can be used for cattle feed, the price is usually too high for general garden fertilizer use.

Cotton flour is ideal for plants that prefer an acidic environment (azaleas, rhododendrons, roses), fertilizer helps reduce soil alkalinity. All components of cotton flour are released slowly and the risk of overdose is minimal, and cotton fertilizer is recommended for heavy soils.

Cottonseed meal for cattle

Dried Blood

Perhaps the most valuable single fertilizer available – organic or inorganic – because it contains in quickly soluble form every element needed by plants for growth.

Only the cheaper grades of dried blood (which contain about 9 percent nitrogen) are used as fertilizers, however, since the better grades are used for industrial purposes and cattle feed and thus command high prices.

Fresh blood, sometimes available from local slaughterhouses or from poultry processing plants, can be adsorbed on peat moss, vermiculite or similar materials and used in that state.

Nothing gives foliage plants as fine a dark green color as does dried blood.

Fish Emulsions

These fertilizers are produced by soaking trash fish, offal and scraps in water to extract all the solubles. This extract is then condensed until it contains less than 50 percent water.

Surprisingly, the condensed product does not have an offensively fishy odor. The method of extracting insures that all elements are present in soluble form and are readily available to plants.

fish fertilizer

Like dried blood, fish emulsions (they contain considerable blood) provide every element needed for growth. In my experience they are ideal for shade-loving plants like tuberous begonias, gloxinias, African violets, and so on.

Fish emulsions have a nitrogen content of about 5 percent, but they should not be judged solely on nitrogen.

Sewerage Sludge

Perhaps this is the most widely used of all organic fertilizers for lawns. Activated sludge is a black, flocculated organic material produced by treating solids in sewerage and allowing them to settle out in special beds.

If the nitrogen content is more than 5 percent and the analysis shows any amount of potash, the chances are that the sludge has been doctored with additional chemical nitrogen and potash.

Activated sludge is a good conditioner for other fertilizers that tend to cake in the bag, hence it is used to a far greater extent than most gardeners realize.


This is made up of packing house wastes steamed to extract the animal fats. The remaining tankage contains between 6 and 10 percent nitrogen.

How To Increase Nitrogen in soil

When you cultivate a garden, you want to make sure your plants grow in the healthiest conditions possible. There’s no nutrient more important to the health of your garden than nitrogen!

Boosting Nitrogen with Fertilizer
Using Plant Waste
Distributing Animal Waste
Fertilizing with Animal Manure

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