It only takes minutes after application for soluble fertilizers to make their way into the plant's nutrient stream. Many nutrients need to be in the nutrient stream constantly for the plant to grow normally. Nitrogen, phosphorus and potassium are considered mobile nutrients and are readily borrowed from one plant part to sustain other parts, particularly strong sinks like new growth o flowers/fruit. Calcium and boron are usually considered immobile nutrients, and need to be in the nutrient stream at all times for normal growth to occur. Sulfur, chloride, copper, zinc, manganese, iron and molybdenum are intermediate in mobility, and only under certain circumstances are intermediate elements mobile. The mobility of the intermediate mobile nutrients is usually linked to the breakdown of amino acids and proteins in older parts of the plant under low nitrogen conditions and their movement to younger parts of the plant via the phloem stream. Again though, unless nitrogen availability is good, these elements are mostly immobile.

That it rains doesn't mean all the fertilizer you applied is washed from the soil. Elements attach themselves to colloidal surfaces and tend to remain there to some degree until they are exchanged. Cation exchange in soils occurs when root hairs utilize proton pumps to pump hydrogen ions (H+) into the soil. The hydrogen ions effectively displace the cations that are attached to negatively charged colloidal surfaces, making the cations available then for root uptake and incorporation into the nutrient stream.

AL

Thanks for the detailed response as always, Al!

Al,
Thanks for the very informative responce. I have pondered that very question that Starlady asked countless times and until now watched the weather and cut the drip system off for at least 36 hrs.
Al,I've said this before but I want you to know that I have learned a lot by reading and trying your way of doing things as far as container growing gos. I used to think I knew what I was doing, wellllllllll you came along and I learned how little I knew. I actually try to teach people what I have learned [ mostly from you] and give gardening lessons to friends and the people they drag over here. The cool thing is when they get to the back yard and see the results that your medium in containers, foliage pro, a good drip system, etc can look like they go back to the car and get there notebook. I Thank You Sir

Plant em if you got em.
Sam

Oh my, Sam! What a nice thing to say. I have always made it known that I get my biggest kicks from the the thought that I might somehow be helping to improve someone's growing experience; but to know there is a secondary impact growing from all the friends I've made that now want to share is an even greater blessing (for me).

I talk to a lot of groups here at my home and at their meeting places too, and I share with you the satisfaction that comes from seeing 'the light' go on when what you're trying to relate actually registers. I find it to be SUCH a rewarding experience - again, it comes full circle to the thought that it makes me, and I assume you, feel like we've genuinely helped.

Thank you, Sam.

Al :-)

I like how synthetic ferts work so quik and effective the problem is this is what is messing our farm land up though.I always used MG but now i found that good old fish fert is just as cheap and more effecetive. it has vits and minarals and micro. way more than the meriacl grow. You may fined fish fert is all you need maybe some bone meal or crab shell for calcuim and tht is all your plants will ever need. If you keep feding with mircal grow your soil will have salt build up. Organic is slow and forever synthetic is good for a short time.

TheMasterGardener, in a container with freely draining soil salt build up should not be a big issue as one can flush the medium quite easily by just watering heavily.
There is nearly no risk of overwatering if your mix has no perched water.