Nitrogen fixing- does clover rob Nitrogen from soil?

[pippo]

People,

 

Say, you have clover in a pot with a small tree. Now, Clover is supposed to fixate N from the air, and release it into the "dirt". But, IF you add N fertilizer, will the clover "turn it down", and leave the N for the tree to take up, or will it hog some of the N for itself, even if it fixates it from the air?

 

Thaks

[chadn737]

This is a complex question.

 

The plant can't distinguish between nitrogen fixed by rhizobacteria or applied nitrogen. Its going to take up both. The real issue is whether or not at the end of the day more nitrogen has been left in the soil than removed. I am not familiar with any research on applied nitrogen with clover, but there is quite a bit that has been done with soybean, another legume. One thing that has been learned is that applied nitrogen oftentimes inhibits nitrogen fixation. The act of developing rhizobia and forming the symbiotic relationship with the rhizobacteria costs the plant energy...considerable energy. In the presence of a high nitrogen environment, it is more energy efficient for the plant to simply obtain its nitrogen from the soil than to invest energy into the rhizobia. So there is a tradeoff in the fixation. However, these sorts of results come from soybean fields, where soybeans are the only crop. Planting your clover next to a tree, you now have a non-legume in the mix consuming nitrogen as well. This may offset the situation.

 

Quite simply I have no simple answer for you.

[CharonY]

Typically, both will compete for the available nutrients until it becomes limited at which point nitrogen fixation may start to occur. If nitrogen is provided in excess, both will happily utilize it. As chadn737 explained, just because the plant has the potential to symbiotically fix nitrogen, it will not initiate it until it senses nitrogen limitation.

[pippo]

good explanation, people. Makes sens biologically too. Thnaks. Time to add N to my tree!!

[Hyena]

For your question, should it matter?

 

Even if all nitrogen from the soil is utilized by the clover, would it not then return to fixation of atmospheric nitrogen?

 

Assuming there is enough N produced by the clover to sustain your tree (hoping it's a small one) from its fixation, the result should simply be that the resources available in the soil will be utilized until no more is available - at that point, intake by the tree would be limited to what the clover can produce; if it enough to sustain structural and metabolic processes (mostly implemented towards chlorophyll, methinks), then the tree should at least be able to survive.

 

-Hyena

[Moontanman]

I grew up on a farm, we always plowed clover under to keep it from competing with what ever we were going to plant, clover grew during the fall and early spring.

[CharonY]

For your question, should it matter?

 

Even if all nitrogen from the soil is utilized by the clover, would it not then return to fixation of atmospheric nitrogen?

 

Assuming there is enough N produced by the clover to sustain your tree (hoping it's a small one) from its fixation, the result should simply be that the resources available in the soil will be utilized until no more is available - at that point, intake by the tree would be limited to what the clover can produce; if it enough to sustain structural and metabolic processes (mostly implemented towards chlorophyll, methinks), then the tree should at least be able to survive.

 

-Hyena

 

Why would the clover release nitrogen to the trees while it is still growing?

[tantalus]

 

Why would the clover release nitrogen to the trees while it is still growing?

Living mulch systems can use clover, depending on the type, such as white clover. White clover can grow using its stolons. Presumably there is a continual turnover of biological matter and some of the Nitrogen is returned to the soil when older biomass, above and below ground, decomposes. White clover stores much of its Nitrogen in its roots. I do not know what the rate of decomposition is, nor the amount of nutrients that the plant fails to withdraw into its healthy structures before the onset of decomp or the extent that another plant can access that those nutrients instead of the clover just reabsorbing them, but there is potential scope for a plant to benefit from the fixation of clover while it is still alive.

 

Such systems are not that common commercially at the current moment, although I believe they are more popular in perennial systems like orchards so may be relevant for the OP's tree. That said, they also offer a wide range of other potential benefits, so fixation might not be a key motivator in the their present or future utilization in many instances.

[pippo]

Sure can be complicated, but thanks people, for all the info/perspectives. Overall, I dont hate clover- just when I see it growing so vigorously, Im suspicious its taking some from what I put down for the trees.........But I dont think it can take ALL of it. Kinda like mosquito larvae in a pond with sunfish- the fish camnt eat all the larvae.

[Harold Squared]

Nitrogen is not the only vital nutrient which plants compete for. The roles of potassium, phosphorus, and trace minerals can be most significant. As an example I am fairly certain that magnesium is vital to the structure of the chlorophyll molecules in all cases. Chlorosis can be caused by insufficiency of magnesium as well as nitrogen and even by a shortage of iron.

[pavelcherepan]

Nitrogen is not the only vital nutrient which plants compete for. The roles of potassium, phosphorus, and trace minerals can be most significant. As an example I am fairly certain that magnesium is vital to the structure of the chlorophyll molecules in all cases. Chlorosis can be caused by insufficiency of magnesium as well as nitrogen and even by a shortage of iron.

 

Harold, the discussion was about nitrogen, wasn't it? By the way, the discussion point has ceased and the OP hasn't been online since October 2014, so if you want to discuss this topic it's better to create a new thread.

 

Edited April 6, 2015 by pavelcherepan

[Harold Squared]

I got here as fast as I could. If this thread or others are not fair game for commentary perhaps they should be deleted. I see nothing wrong with consulting archives personally nor do I understand how a valid point can be out of date somehow merely due to the passage of an arbitrary period of time. Your own post of machine gun guy has much less to do with topic of OP than my post, coincidence or fact?

Edited April 6, 2015 by Harold Squared