How does extra phosphate stimulate plants to grow more than they would with only an adequate amount?

Question

I'm looking for the biochemical mechanism here, not just the usual "because it makes them grow" sort of non-answer.

Answer 1

Adequate phosphate means just what it says, it is the right amount to meet the plant's needs.  Extra or excess phosphate will be lost as runoff and the plants that will be stimulated to grow are aquatic weeds in the waterways.  Excess phosphates and nitrates are two of the biggest problems contributed by agriculture in our environment.  Encouraging application of extra phosphates is not a place we need to go.

Answer 2

P works at the very early stages of the life of a plant and it promotes the increase of roots' dry matter deposit.

A plant with a stronger and heavier root system is usually a more vigorous plant.

It makes the plant more able to survive in case of a drought.

Answer 3

usually phosphorus is a root activator, therefore, adequate means enough, but it depends on what type of phosphoric form . in my exprience the liquid form of phophorus fertilizer (as phosphoric acid) is best for we inject it direct to the rootzone of the plants by drip, though we inject it to a very minimal amount based on ppm(parts per million) by %age availability. And we found out little at a time is much better than giving the required and recommended amount  at one time as based on soil analysis & foliar analysis. So in totality, it is almost the same as human, if we need a food per day, we can not take our one week need at one time but must do it on a daily basis, in plants like wise we found out, that we calculate requirements based on economic point of view of applying any fertilizer per se! not to overdo and will fall on economic threshold of applying fertilizer. to economic point of view shall we say if it is production for business purposes!

Therefore,

1. timing of application must be known for effective use of the nutrients by plants.

2. economic consideration (assuming for agricultural business)

3. must know the character of plants you're applying either fast growing or slow growing type of plants.

4. split application or little at a time of the required is better if it can be justified by the cost of application.

5. and the type of phosphate to be applied

6. adequate application means sufficient enough and again depends on the plants!

Hope this helps and give you the idea. i may not able to satisfy the direct thought of your question.