Nitrogen
Phosphorus
Potassium
Sulphur
Calcium
Magnesium
“WITH hydroponic
growing, many grow
mediums do not
naturally contain
secondary nutrients
and micronutrients, so
attention to these ‘lesser’
nutrients is critical.”
Iron
Manganese
Boron
Copper and Zinc
Molybdenum
4.0
5.0 6.0 7.0 8.0
9.0
Fig. 3
MAGNESIUM
Magnesium is very important for plant health as it is key in a plant’s ability to produce
and retain chlorophyll. The energy required for plant growth comes from photosynthesis
and this process only occurs because of chlorophyll. Without chlorophyll, plants cannot
manufacture food and life as we understand it would cease to exist. Magnesium is
also important for various plant enzyme systems. Stunted growth is often the result of
magnesium deficiency. Magnesium is usually available naturally in most soils and is
often overlooked as an important nutrient that may be needed for the health and vigor of
a crop. Magnesium becomes available within the soil by weathering processes on other
natural minerals. Magnesium availability to plants is subject to soil pH.
Magnesium becomes subject to removal from soil when that soil is sandy or has a
low pH (is acidic). Some crops will use and remove much more magnesium than others.
Sugar beets and corn are two crops that use larger amounts of magnesium.
The ratio of calcium to magnesium availability is important. For soils with a cation
exchange capacity (CEC) higher than about five ME per 100 grams, it is often a good idea
to maintain the soil Ca:Mg ratio at about 10:1. For sandy soils (which leach more rapidly)
having a CEC of five ME or less, it’s generally best to maintain the ratio at about 5:1.
Outdoor agriculture has long focused on the primary macronutrients to maintain and
improve plant health and yield. This has generally been successful as soil naturally
provides most of the essential nutrients, though there are exceptions in this practice due
to climate and location. With hydroponic growing, many grow mediums do not naturally
contain secondary nutrients and micronutrients, so attention
to these “lesser” nutrients is critical. As our outdoor growing
acreage continues to come under nutrient stress due to crop
utilization, and as we grow more of our food using hydroponic
methods, we will need to make certain our fertilizers contain a
complete balance of all the essential nutrients that plants need.
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grow cycle
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