UNDERSTANDING
NITROGEN
SOURCES
HYDRO
FOR
PONICS
Nitrogen is a fundamental element for healthy plants but in hydroponics , growers need to know the different nitrogen forms and sources , and how plants process them when used in nutrient solution .
by Lynette Morgan
Unlike other elements , nitrogen sources for hydroponics can be little confusing . Plants can take up both nitrate ( NO 3- ) and ammonium ( NH 4 +) and these can be supplied via several different fertilisers and organic sources . Understanding how plants process nitrogen sources and the effect these can have on growth , development , physiological disorders , nutrient interactions , and solution pH are all aspects of hydroponic plant nutrition we should know a little about .
Why is Nitrogen so Important ?
Severe nitrogen deficiency results in yellowed , spindly , and weak plants .
Nitrogen ( N ) is an essential component of amino acids in proteins and chlorophyll and , along with potassium , is a macroelement required in large quantities for uptake . Foliar N levels for most crops are in the three to six percent range depending on species and stage of growth . Without nitrogen , growth will rapidly dwindle to a halt , and deficiency symptoms such as yellowing or purpling of the lower leaves will occur as nitrogen is mobilised from old to new foliage . Nitrogen-deficient plants are often quite distinctive with spindly , thin growth , limited root extension , fruit and flower drop is common , and yields severely reduced . Excess nitrogen , however — or more specifically a high nitrogento-carbon ratio — can cause problems of its own , including lush , soft foliage growth , reduced shelf life , and an increase in calcium disorders such as tip burn . Plants also have the ability to take up luxury amounts of nitrogen , well beyond their actual requirements . Balancing nitrogen uptake and obtaining the best results from the nitrogen sources used in a hydroponic nutrient solution can vary from crop to crop and under different growing conditions , however , there is potential to manipulate this to improve crop growth and yields .
Nitrate and Ammonium in Hydroponics
Nitrogen can be supplied in two forms in hydroponic nutrient solutions : Nitrate ( NO 3- ) is the dominantly used source , while smaller quantities of ammonium ( NH 4 +) can also be applied . Both are available for plant uptake and are supplied via fertiliser such as calcium nitrate , potassium nitrate , ammonium nitrate , ammonium sulphate and even , in much smaller quantities in the nitric acid used for pH control . When nitrogen is absorbed as nitrate , inside the plant it becomes mobilised first to ammonia and is then incorporated into the amino acid glutamine . When the ammonium form of nitrogen is supplied , the ions are absorbed rapidly by plant roots , but they must not be absorbed more rapidly than they can be utilised in the plant tissues or a toxic reaction will occur .
Maximum Yield 37