Fertilising - works best when?

[fredman]

Now that is well said. Even I understand that

[bonborn]

Hi Daluke,
Following Brian's advice, when using liquid fertilizer I would always water first before applying the fertilizer. If you water first it wouldn't matter if it was morning or afternoon.

Regards Ray

Now this confuses me. I always did it the either way round. Someone please tell me i am wrong. My thinking was that the dry soil will hold the liquid fertiliser rather than letting it run of. I always waited to fertilise when the soil was dry.

It is the same principal of when a child takes anti biotics. They are strong, and you don't want to give them on an empty stomach, otherwise the body starts to use them without any dilution or anything else to digest.

The analogy is the same, because a tree in nature, doesn't get liquid fertilizer poured down its throat, so by wetting the roots first, you will give the plant water to absorb as well as fertilizer afterwards to mix the intake.

For example, when you take a large multi vitamin pill first thing in the morning, you often feel horribly nauseous and may throw up from the sudden intake of concentrated vitamins if you haven't eaten anything first. Yet, if you eat a meal before hand, then take the multi vitamin pill you don't experience any problems. It is the same for plants/trees.

But don't we dilute the liquid fertiliser as per instructions given. I always dilute seasol and then water using a watering can. When the soil is dry it takes up most of the liquid rather than letting it run of. I then follow this with normal water the next time soil feels dry again.

[Phoenix238]

I've seen mentioned a few times about watering twice, once to prepare the soil mix to accept water and the other to actually hydrate it. When it's dry it doesn't absorb water properly and half of it runs straight through, or something like that. I usually presoak mine

[Rory]

You can do it either way, but if you water it first, then the first thing the roots are exposed to is water and not fertilizer. It depends on different factors. Everyone has their own regime. Watering after you apply the fertilizer has the potential to wash away the fertilizer, so I am not sure why you would water after you have applied the diluted fertilizer. Anyway, if you haven't had problems before, then continue doing what you're doing. There are all different strengths of fertilizer on the market, so I wouldn't be too concerned about the theory behind it. Watering and fertilizing is a personal preference.

[Phoenix238]

I like the quote "doing is better than perfect" ie. You're better off doing something than being indecisive and not doing anything trying to find the perfect answer

[treeman]

Evenings, after tea when it has started to cool down...
Never fertilise if your soil/air temp is below 14 (cation and anion exchange doesn't take place below 14)
Never fertilise in the mornings if you are in daytime temps of over 28-30+ (root burn, plant stress)

There seems to be some confusion as to exactly what takes place when you fertilize.
To begin with, Cation Exchange is an electric process. When you apply a cation (Mg+ Ca+ K+ NH4+) they are attracted to negatively charged particles in the soil. These sites give up and take cations continually depending on the concentration in the water of the media. It can happed at any temperature. (if it didn't, your lawn would starve in winter). Growth response of plants to temperature is directly related to where they originate. Tropical plants may have difficulty with temps below 20C where's a temperate species from the mountains would function perfectly well with 5C.

Root burn.
It is a misnomer. What really happens is that when the EC (electrical conductivity) of the water media becomes greater than the that inside the roots, They begin to give up water and if the EC is high enough the roots will die and get attacked by bacteria and fungi. There is no ''burning''

The high media EC is caused by using to high a concentration in your dilution. If you maintain a high water level in the soil you will see less root damage. Remember that after you liquid feed the EC in the media doubles when the half the water is evaporated or taken up.

There is absolutely no problem feeding when day temps are going to be 30. The temperature will not cause the problem. Quick drying of the soil may if you do not keep the water at an adequate level.

The problem is different when you use solid organic feed or controlled release feed (osmocote etc). With these you MUST keep the water level in the pot high because increasing temps increase the release rate. But again this comes back to appropriate application. I use all three types and I have never experienced root damage even at temperatures of 35C.

Watering before fertilizing is not needed when the media is moist (ie when you watered the day before).
Watering after fertilizing is just silly.

[squizzy]

Treeman beat me to it. But I thought it was an osmotic thing?

I remember something about liquid feeding and osmosis. Something like higher concentrates moving through a cell wall to lower concentrates. This is where "burn" occurs. I can't remember exactly how it goes but it meant basically have high salt dry cells inside the plant have higher salt concentrates and then the liquid feed on the outside of the cell so the lower concentrate liquid draws the high concentrate back though the cell wall into the soil? Is this about right treeman?

Squizz

[treeman]

Treeman beat me to it. But I thought it was an osmotic thing?

I remember something about liquid feeding and osmosis. Something like higher concentrates moving through a cell wall to lower concentrates. This is where "burn" occurs. I can't remember exactly how it goes but it meant basically have high salt dry cells inside the plant have higher salt concentrates and then the liquid feed on the outside of the cell so the lower concentrate liquid draws the high concentrate back though the cell wall into the soil? Is this about right treeman?

Squizz

That's exactly right!

[GavinG]

Since I didn't know you shouldn't fertilise dry trees, mine have been fine when I do. Standard rates, no burn. Getting around to it is the real problem.

Gavin