Phosphorus In Plants and Soils

Phosphorus (P), an essential macronutrient, is a vital component for several different factors of plant growth.  In the list of essential nutrients, there are two categories which help to divide the elements up based upon the quantities required for plants to thrive:  macronutrients and micronutrients.  Macronutrients are nitrogen, phosphorus,  potassium, calcium, magnesium and sulfur.  The first three macronutrients appeared to be so vital in plant nutrients their percentages, by weight, are found on the label of all fertilizers.  This is rather strange given the fact that calcium is more important than phosphorus for all plants.  Even more significant is the fact that calcium is rarely present in common fertilizers.  Look at the label the next time to see if there is any calcium in the product that asks you to rely upon “Miracles” when feeding your plants.  Moreover, magnesium is more important than phosphorus for a large number of plants.  Does your fertilizer contain magnesium?  Phosphorus levels less than 0.3-0.5% of dry matter weight are likely to lead to deficiencies.  Levels higher than 1% are likely to result in phosphorus toxicity.

So, just what is it that this macronutrient phosphorus is able to do for your plants that makes it so crucial that you maintain sufficient levels for all of your plants?  Phosphorus is a component of the complex nucleic acid structure of plants, which regulates protein synthesis.  Phosphorus is, therefore, important in cell division and development of new tissue.  Phosphorus is also associated with complex energy transformations in the plant.  Like nitrogen, phosphorus forms an essential part of photosynthesis.  Specifically, photosynthesis is the process of converting light energy in the presence of chlorophyll to produce simple sugars, and capture the energy in the form of ATP.  ATP stands for adenosine triphosphate, which contains three phosphate ions.  ATP is the cells primary energy source.  It is used to power everything that happens in plants and animals.

If there is a deficiency in the levels of phosphorus in your plants, it will be much less efficient in how it is able to convert sugar into fuel for growth.  Deficient levels of phosphorus means a decreased rate of growth.  Phosphorus is also believed to encourage blooming and root growth.  If there is not enough present in your plant and in the soil surrounding it, then both of these processes can be retarded.  An adequate supply of phosphorus is essential to the development of new cells and to the transfer of the genetic code from one cell to another as new cells are formed.

With all of that in mind, what are the symptoms that come with a phosphorus deficiency?  Stunted growth could be from any number of different nutrient deficiencies.  There are some ways to be able to tell and distinguish to give the gardener an opportunity to compensate for any potentially fatal crop or soil deficiencies.  Plants that are deficient in phosphorus are stunted in growth, reduced leaf expansion and surface area as well as a very unusual dark-green coloration to them.  Phosphorus deficiencies inhibit formation of reproductive organs, flower initiation is delayed and numbers decreased, and premature senescence of leaves can occur.

There could also be the development of anthocyanin pigments that give off a reddish-purple color in the cases of extreme phosphorus deficiencies.  If your plant is exhibiting these types of discolorations, then the time to act is right now if the plant is to grow to its potential.  These different colorations could be natural from your plant species, however.  Fewer leaves on the plant could also be the side effect of low phosphorus levels.  Also, be sure to check that the root mass looks appropriate and strong as lessened root growth is a very strong indicator of a low P level in your soil.  Some of the other effects that a lower level than needed of P could include delayed maturity, poor quality forage, fruit, vegetable and grain crops, as well as a much higher sensitivity to disease.

Keep all of these factors in mind as you watch the growth of your plants to be able to diagnose a deficiency of phosphorus and take the necessary actions to be able to compensate for such a scenario.  We are proud to offer Liquid Bloom, Liquid Grow and Mag-Pro® to eliminate these devastating effects which a phosphorus deficiency has on all plants.

Remember that phosphorus can also become toxic to plants at high levels.  This is most unlikely in hydroponic growing.  But levels of phosphorus can build up in soils, particularly where high levels are applied with little leaching from rain.