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Compost: A Discussion!

January 3rd, 2010 · 1 Comment

From Dan and Michael – from a series of emails!

All mixes measured in 5 gallon buckets

The EPP Organic Mix

2 buckets aged stable cleanings (horse manure plus straw, hay and  a few wood chips)

1/2 bucket of pine bark fines *

1 quart plus or minus (depending on the plant) of perlite

1 quart (approx.) of coffee grounds

roughly 1/2 cup of each: colloidal soft phosphate rock and New Jersey Greensand

1/4 cup dolomite lime (or none for acid loving plants)

a small scattering of soil innoculant

a tiny pinch of mined (not chemical) potassium sulfate

– I think that is everything.

My Personal Organic Mix (for my own garden!)

3 to 4 buckets pine bark fines *

2 buckets wood chip compost (from the Wood Resource Recovery facility north of Gainesville on SR 121, $12 per cubic yard)

1 or 1/2 buckets aged coffee grounds (Free from starbucks if you are very regular about picking them up and don’t leave them with big messes of fermenting grounds.  Use the 1/2 bucket measure if the plants are slow growing, a full bucket for veggies or tropicals.  See the note below for aging them.

1/2 bucket perlite for deep containers or for plants needing a bit more drainage – but usually the extra pine bark fines work well for ensuring drainage and they are cheaper than perlite so most of my mixes don’t use perlite these days.

5 cups rabbit food or alfalfa meal pellets (rabbit food from any pet supply dealer or department store, alfalfa meal pellets from some feed stores, both cost about the same and add the same trace nutrients, kelp meal is better but costs more)

1 cup colloidal soft rock phosphate (hard rock phosphate might work but is much slower to release so you’d need to add something organic with quick release phosphorus in it)

1 cup New Jersey Greensand (very slow release)

1 cup dolomitic lime like Soil Doctor (use no lime if you are growing acid loving plants)

a handful of any good bacterial and fungal soil innoculant.

occasionally (depending on the plants and my mood) a half cup of clean wood ashes for extra quick potassium

My Personal Not-So-Organic Mix (for my own garden!)

Use the larger amount of pine bark above and the smaller amount of coffee grounds, add 1 cup of “propagation” grade (12 to 14 month) Osmocote Plus with micronutrients (which is half the recommended strength for the low rate application), cut the rock powders about in half, and eliminate the rabbit food. For plants that need very quick release nitrogen (like leaf veggies) I sometimes add Super Rainbow 16-4-8 fertilizer instead of the Osmocote - I get the Rainbow stuff  from Alachua Farm and Lumber but it may be available at other farm stores. This has trace nutrients and is pretty much the top of the line for bagged commercial fertilizers. It beats the heck out of 6-6-6 which, in addition to its very suspicious name, doesn’t have the trace elements and adds too much phosphorus for almost everything.

Note on Coffee Grounds: if using fresh coffee grounds reduce the amount to no more than 5 to 10 percent by volume and add more rabbit food or alfalfa meal or throw in some other nitrogen source like blood meal.  For the EPP mix the stable manure adds the extra nitrogen but for my home mixes I don’t use stable manure. Aging the coffee grounds makes them usable at high concentrations and prevents some strange growth problems that happen with large amounts of the fresh grounds in a potting mix.  To age them leave the grounds under a tarp in a large pile for five or six months so they heat up then cool off. For smaller amounts, leave in a covered water tight container until they sort of liquefy then put into a covered drained container and dry them out. If they don’t liquefy by themselves add a little water to help them along. The aging process makes them partly form into hard clumps which are a somewhat slower released source of N and is much more mellow.

Note 2:  I haven’t yet fully optimized the nutrients for my home mixes, there may be more of one thing or another than is absolutely needed.  But the mixes work fine for veggies and potted shrubs and I catch the container effluent (runoff) and pipe it to trees to make sure I’m not wasting anything. Also, the spent potting mix (after the stuff gets weed seed infested or breaks down into muck) also goes as mulch under fruit trees or in other gardens on the ground. Waste not, want not.

Oh yeah – don’t forget to add a good measure of fire ants to make the potting experience much more fun!  :-)

* Pine bark fines from Griffis Lumber on 441, about $22 per cubic yard – or grind your own from regular size pine bark run through a wood shredder – you need about 1/2 inch to 3/4 inch diameter pieces, don’t mill to a powder!)

From Michael to Dan

The EPP container mix usually does not contain any lime or dolomite.  We used to put some in for things that like basic conditions, but I don’t think our mix ever quite gets acidic enough for that to be useful.  We’ve generally been having the opposite problem for plants that like acid, although the same symptoms can be caused by too much potassium.

My approach to the soil mixing is like cooking, I don’t like to measure, I just add stuff till it looks right.  The plants growing in the soil I cook up are almost always happy.
For vegetable seedlings that need extra nitrogen, I mix in blood meal.
This information is really not very useful for gardening unless you are doing it all in containers.  Most gardening uses natural soils and adds things that are lacking.  For that you need a soil test.  Soils around here usually need most of the things you can add, such as, dolomite, organic matter, NPK, and micros.  To know just how much of all those things you need to add, you need a soil test that you can get done for $15 at the University’s soil lab. Contact the IFAS extension and ask for a soil sample kit.  They will mail it to you for free.  It will tell you how to collect you sample and deliver it to the appropriate office.  The only thing you can almost never get too much of is organic matter.  Some sources are low in Nitrogen and will use whatever is there in the decomposition process.  Some people who read a badly written pamphlet often tell me “oh, you can’t use that, the C/N ratio is all wrong.”  No, it means you need to pee on it…or add some other source of nitrogen to balance it – blood meal, fish emulsion, any kid of legume residue, synthetic fertilizer, etc.  I also get “You shouldn’t use oak leaves or pine needles for mulch because it will make the soil too acidic.”  Wrong again.  Adding oak leaves and pine needles for thousands of years will make the soil too acidic.  Then you’ll need to add a little dolomitic limestone, and can continue with the oak leaves and pine needles again.

From Dan to Michael

Yep - the mixes I listed are entirely for container gardening which is pretty much most of what I do other than the fruit trees and shrubs I plant in the ground.  Too many tree roots where I live to grow anything that isn’t strongly competitive so most things go in bins, boxes, trays, bags, and pots and I isolate those from the soil either up on blocks or with black plastic sheeting.   For planting in soil its a whole nother ball game.
For the EPP mix I should have said dolomitic lime for alkaline loving plants rather than not for acid loving plants – in other words we don’t use it most of the time.  My bad.  At home I use so much acid to mildly acid materials (pine bark, coffee grounds, compost) I add the dolomite as a default and only leave it out occasionally (for potatoes, strawberries, etc.). So my brain is set in a pro-lime default mode.   I think the irrigation water at the blueberry farm must add plenty of calcium carbonate (lime) for us from the hard well water.  In fact, I think if you stand still long enough under the sprinklers you’ll develop a bad case of stalactites.
Dan

ps – for the true container gardening geek there is a good article on container mixes at http://edis.ifas.ufl.edu/CN004 .  Some things there are counter to my experience but it is a great overview of things to use and factors to consider.  A bit too deep in theory for most people. But I rather like theory since it is so pleasant to defy it and still succeed. :-)  Like Michael indicates all that is important in the long run is that the plants do well in the mix, not whether a soil scientist thinks it is properly drained or all the ratios are right.

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