There are two ways that inorganic substances can leave a pot, by mechanical movement, or by dissolution. If these are "fines" of some kind it is possible that they are just being carried by the water, and being caught up in the mesh of the bag. Or, if they were dissolved, they could be crystallizing again, as the run-off from the pot dries.

Would lime be the best suspect? Possibly, it is white. But it could also be calcium and etc from your water.

I suspect it happens with all pots, and you just see it because of the fabric.

Or course, if everyone else with fabric pots says "I never see that!" it might be an issue.

Update: upon reflection, I think it likely that they are just lime "fines" washed mechanically, and seen only because you use the bag.

This post was edited by johns.coastal.patio on Wed, May 7, 14 at 15:58

How was the mix made?

Did you moisten the bark and peat and perlite, and then mix the Lime in, evenly coating the ingredients?

Did you make the mix dry? Did you add the mix dry to your containers and *then* try to water?

As John suspects, I, too, suspect this could be Lime.

Josh

Just an idea:
Can you just top dress the lime, instead of premixing? This can also apply to CRF.

I think , this way there will be less of leaching.

No, top-dressing is not a good idea with Lime.
The point is to incorporate the Lime evenly throughout the mix. Same with CRF - much more efficient if mixed throughout.

Josh

Strikes me that if you have a coarse mix, and a slowly soluble powder amendment, it will mechanically wash out. That is the nature of the materials.

Wetting, to make something "stick" only works until the first "flush."

Perhaps you want a slowly soluble but large granule material.

I used dolomitic lime mixed in thoroughly with the CRF and and the 5-1-1 ingredients, filled my bags, then watered them heavily prior to planting my broccoli in early April (which by the way did not grow at all).

Since I need the growing mix for my tomatoes in less than 2 weeks I just dumped them into larger 20 gallon bags. Now I'm concerned that the lime I added won't last very long and my plants will suffer. What should I do to compensate considering the fact that I will need to water my bags much more frequently than if I had used non-porous containers.

John, that's one of the reasons that it's a good idea to make the 5-1-1 a few days ahead of time (or a week or two if possible). I've certainly mixed and planted the same day, but I'm always sure to make a moist mix that will hold onto the majority of the Lime.

Njitgrad, for future batches, moisten your mix in a big tub or wheelbarrow, et cetera, prior to putting it into your pots/bags. Then, do a light watering to settle your plants in. This will prevent dry-spots in the mix (which is seriously detrimental to the roots of a transplant) and will help the mix retain the powdered Lime.

Josh

Hmmm. Borrowing from some of the 420 guys, "Dolomite lime is finely ground dolomitic limestone and contains a ratio of Ca and Mg, but it isn't water soluble, it is dissolvable over time and is therefore a slow release additive and buffering agent.. pure Ca limestones are more soluble than dolomitic limestones"

If that's true, you've got a "fine" for slow release in a course medium.

I wouldn't see that binding to the medium, I'd see it as mostly inert.

The Lime phase reaction takes 2 - 14 days on average, depending upon moisture and temperature.

Josh

Hmmm. Here is an old field experiment:
The limestone dissolutions for the 3-month period were very similar in both soils (Table 2). The values for the two calcite particle sizes (18 and 35-mesh) were about 26 and 42 percent; for the smaller dolomite particle sizes (60 and 120-mesh) about 38 and 64 percent. These three-month results agree with those obtained in New Zealand (4 & 5) but are higher (150 percent) than those obtained in Ohio (17). At the end of I year the two particle sizes of calcite in the Hartsells soil had undergone 80 and 92 percent dissolution; in the Claiborne soil, 62 and 86 percent. The dolomite dissolutions in the Hartsells soil were 70 and 89 percent; in the Claiborne soil, 80 and 94 percent. At the end of 2 years all but the 18-mesh calcite separate had completely dissolved. The maximum pH value of the Hartsells soil was 6.3 and that of the Claiborne soil, 6.6 to 6.7.

It seems likely that what you've got in 14 days is the "first cut" of a multi-year process.

Here is a link that might be useful: 1960 study (PDF)

Josh, evenly mixing in CRF isn't the most efficient way. You get more leaching that way. It is better to put some just under where the roots are going to be when planting and then the rest worked in to the top. The water carries the nutes down into the medium. Topdressed nutes stay in the container longer.

This discussion may be starting to get a little too technical for me. Can anyone offer advice as to whether I need to take correction action or not, now or during the growing season? I thought that the 5-1-1 was a set-it and forget-it mix but it appears that would only apply to non-fabric containers. Should I periodically add more dolomytic lime?

I'm the "don't worry guy" so maybe it will be hard to believe me when I say "dont' worry" ;-)

You are doing the same thing as thousands of other 5-1-1 users, and it works for them.

There are hydroponic growers to the right of us, there are permaculturists to the left of us. Many things work, and 5-1-1 is certainly one of them.

okay, I feel better now :) but perhaps you can give me some early warning indicators to look for after I transplant into the 5-1-1 so I don't take too long to react to a necessary corrective action

Abnormal leaf colors would be a clear signal that something is amiss, but other than that, it would be reduced growth.

My logic really is that something similar must be common, because coarse 5-1-1 mixes are common and fine lime additions as well.

The chemistry might be that the lime quickly reacts with free and available acids in the bark, and that loss of some lime later is not a big deal.

Nil,
incorporating the CRF works most efficiently in the mix not for its positioning (top to bottom waterfall effect), but for the consistent moisture and temperature in the body of the mix. I've top-dressed and I've scratched CRF into the upper inches of mix and the results just aren't as predictable and consistent as when the entire mix includes the CRF. The upper layers dry down, which halts or interrupts that nice even release, in my experience.

Josh

I think you are confusing efficiency with consistency. There is a study looking at different CRF mix techniques and mixing in like you described shows the most leaching and therefore is least efficient.

Perhaps I am :-)
I suppose that my preferred technique is not as cost-efficient, given your comments on leaching of product. I prefer the consistent glut of nutrients, however, since the cost is minimal and the growth is strong. Leaching may also not be as noticeable for me since I don't water as often as others - every 2 - 4 days during the beginning and end of the season - and only every other day during the very hottest weeks of Summer. This year, due to the drought, I will also employ driptrays to conserve water run-off.

Josh

That's 5-1-1 jizz, don't get any on the sofa!