heres some nitro info for the few that actualy want to learn something.
Plant Utilization
Nitrogen is one of the 17 chemical elements required for plant growth and reproduction. Nitrogen is in chlorophyll, a green chemical which allows plants to capture energy from the sun and make food for themselves in a process called photosynthesis. It is also the basic element of plant and animal proteins, including the genetic material DNA and RNA, and is important in periods of rapid plant growth. Production Nitrogen is an abundant element on and around Earthapproximately 78 percent of the Earths atmosphere is nitrogen gas (N2). As with all plant nutrients, however, nitrogen must be in specific forms to be utilized by plants. Converting N2 into nitrogen plants can use is called nitrogen fixation. Most often, nitrogen gas is converted into plant available nitrogen by using complex chemical processes or nitrogen-fixing bacteria.
Most manufactured nitrogen fertilizers begin as ammonia. At temperatures of 400ºC - 500ºC and great pressure, nitrogen
from the air and hydrogen from natural gas combine to produce ammonia. The ammonia can be used directly or further processed into other nitrogen fertilizers. Legumes such as beans and alfalfa grow specialized nodules on their roots. Rhizobia, nitrogen-fixing bacteria, live in these root nodules and convert atmospheric nitrogen into nitrogen plants can
use. Farmers take advantage of this unique symbiotic relationship by periodically growing legumes in nitrogen-deficient soil to naturally boost nutrient levels.
Forms
In the soil, nitrogen exists in different forms, which interact with one another and with plants, animals and microorganisms. Most crops use nitrogen rapidly, therefore, farmers and home gardeners often supply nitrogen to the plants in a variety of ways, including the application of manufactured fertilizers, applying composts and manures, and growing legumes in rotation with other crops. Plants absorb nitrogen in the forms of (NO3-) or ammonium(NH4+) ions, both of which are water-soluble. Nitrateions are absorbed quickly by plant roots, but leach easily. Ammonium ions are attracted to soil particles and move slowly through the soil to plant roots. Commercial fertilizers, both dry and liquid, are available with various combinations of nitrate and ammonium ions, enabling farmers to manage their nitrogen application. Crop advisors monitor crops to ensure the crops receive optimum amounts of nitrogen.
Plants can take up N in 4 forms:
NH4 Ammonium
NO3 Nitrate
Organic Nitrogen
Molecular Nitrogen
Regardless of the N source (inorganic fertilizer, organic fertilizer, manure, etc.) plants can only take up N in these 4 forms. That means that some conversions must occur in the growing media/root zone (rhizosphere) before some sources of N can be taken up by the plant. All 4 forms of available N have unique characteristics that influence plant growthin different ways. Understanding these characteristics is very important in matching the best N fertilizer with plant species, stage of growth, time of year and production objectives. The following is a brief description of these 4 N forms and some additional information on the most common fertilizer sources for each.
Nitrate NO3 and Ammonium NH4 Nitrogen:
The roots of most plants absorb N from the growing medium in the form of NO3. Nitrogen in this form, however, is not directly used by the plant but must be reduced to ammonia (NH3) before it can be assimilated by the plant. The process of nitrate reduction to ammonia is a 3 step process:
NO3 a NO2 a NH3
Nitrate Nitrite Ammonia
This conversion is dependent of the presence of several enzymes (i.e. nitrate reductase) for the conversion to complete it's cycle. These enzymes, and the microorganisms that indirectly produce them, are effected by several factors including: temperature, moisture, etc. If the conversion process stops at the nitrite stage serious damage may occur. Nitrite is toxic to plants at low to moderate levels and can cause significant reductions in growth at low levels. Both nitrate and ammonium fertilizers are commonly used to provide supplemental nutrition for nursery/floral crops. Ammonium (NH4) fertilizers must first be converted to nitrate NO3 before it can be used by the plant. This is a 2 step process in which ammonium is first converted to nitrate and then the nitrate is subsequently converted to ammonia. This process, known as nitrification, is dependent on several soil microorganisms (Nitrosomnas, Nitrobacter). These microorganisms are effected by several factors including: temperature, moisture, etc.
2NH4 + 3O2 a 2NO2 + 2H2O + 4H
Ammonium Oxygen Nitrate Water
and then
NO2 + O2 a 2NO3
Nitrite Oxygen Nitrate
Ammonium is the most common, and perhaps the lowest cost supplemental source of N for plant growth. Research has shown that the balance between nitrate (NO3), nitrogen (N) and ammonium (NH4) can effect plant growth. In Texas it is recommended that no more than 50% of the N supplied should be in the NH4 form. Increased amounts of NH4 in the growing media may result in severe ammonium toxicity (nitrites??).
Organic Nitrogen:
Many plants are capable of using organic, as well as inorganic N. As they breakdown in the growing medium, many of the amino acids, amides and proteins provide available N for plant growth. However, urea is perhaps the most commonly used source of organic N for nursery and floral crops.
Urea must first be converted to ammonia before it can be used by the plant. This conversion is dependent on the enzyme urease. Urease is another compound that is effected by factors such as temperature, moisture, etc.
NH2 C NH2 a 2NH3 + CO2
Urea Ammonia
Under cool temperatures urease is often rendered inactive and little, if any, N is available for plant growth.
Molecular Nitrogen:
Many plants are capable of fixing N directly from the atmosphere (legumes). This process usually requires the indirect mediation of soil microorganisms. Perhaps the best example of N fixation is in soy beans. Beans are inoculated with specific N fixing microorganisms prior to planting. Nodules are then formed on the root system which indirectly provide atmosphereic N to the plant.
Although several nursery/floral crops have the capability to fix N from the atmosphere, most growers provide supplemental fertility to compensate for the potential lack of these specific microorganisms in soilless growing substrates.
