Phosphorus Deficiency

Phosphorus is a macro, or major, nutrient required by all plants in considerable amounts, along with the other two macro nutrients, nitrogen and potassium. Most people know that phosphorus plays an important role in early root formation and growth. Equally important, phosphorus is involved in the production and processing of energy. It is crucial to photosynthesis and respiration, energy storage and transfer. It is involved in the processes of cell division and enlargement, and is consequently found in highest levels in young plants at the growing points. Inside plants, phosphorus is known to be mobile and moves from older tissue to new tissue quickly.

So, how do we know whether or not our corn is deficient in phosphorus?

Since phosphorus moves from older plant tissue to new tissue, it is no surprise that deficiency symptoms become apparent on oldest leaves first. In general, phosphorus-deficient plants may be stunted, and green areas of leaves may be darker green than normal. In corn, the edges can become a distinct purple colour, especially in cool weather. If your corn is showing what could be deficiency symptoms at the pre-sidedress growth stage and it is an unseasonably cold spring, it may just be the weather. Just wait for the weather to warm up. If the symptoms don’t go away, you have a real deficiency.

What can be done once phosphorus deficiency symptoms have been established in your corn?

Not much. Phosphorus is a macronutrient, which means your corn needs a lot of it. If you can see deficiency symptoms in the foliage, it is a safe bet your soil is very short in this important nutrient. You should have taken a soil sample before preparing your field for planting. Major corrections of soil phosphorus deficiency can be made with application of granular or liquid phosphate, but well before knee-high. You can in desperation sidedress phosphorus into a well-established field, but since phosphorus is immobile in the soil, you would have to basically run down your rows in order to get close enough to your roots. You would be better off to spray or fertigate with foliar applications of phosphate, although the amount you can apply this way is limited. TerraLink has a wide range of liquid and water-soluble phosphate fertilizers if you find yourself in this situation. Contact us today and find out what you can do to help your crops.