And just so we are all clear on this, a fertilizer is NOT determined by soluble NPK, only by measurable NPK, termed the "guaranteed analysis". Soluble or not, NPK can be measured in all fertilizer products, even in compost, should one want to go to the trouble and expense of having their own tested. The USCC (US Composting Council), an industry association of commercial compost operators, does have a testing process and various participants in this organization do offer STA-certified compost with a specified NPK. btw, should there be any questions on what requirements determine a "fertilizer" as opposed to a soil amendment, organically derived fertilizers - those created from animal or plant wastes - are by nature non-soluble. They require the actions of soil organisms to convert them into the soluble nutrient salts that plants can access with their roots. And yet these, whether single ingredient or blended ingredients, are sold as fertilizers with a designated NPK. Solubility - or lack of it - has nothing to do with whether a product is considered a fertilizer. Only a statement of guaranteed analysis or measurable NPK.

You don't add compost to give nutrients, despite what you read on this forum. You add compost to add water holding capacity, tilth, etc.

Dan

I've bought composted steer manure in a bag that had NPK ratings in the range of .5 -.5 -.5 to 1-1-1. I would think good balanced compost is in that range, maybe a bit lower if manure is higher in salts than the average vegetative compost ingredients most of us use. But I have to agree that nobody sits around calculating how many pounds of compost to add per 100 sq. ft. of garden. You just pile on as much as you can.

Dan may not add compost for nutes, but I do. What nutrients there are depends on what you compost. It depends on how you manage it, too. If you don't cover it and it gets lots of water, it will lose nutrients. Particularly nitrogen.

I don't use any purchased "fertilizers" on my garden. That includes organic ones. I use only compost in one form or another. Actually, I did put bloodmeal on my potato box, but that is separate from my garden and is an experiment I'm running. The nutrients resulting from hot compost will not be nearly so available as those from vermicompost. The worms break it down to a soluble level. Plenty of study has been done on castings and the fact that they are nutrient rich. It's why they usually have a guaranteed analysis on the bag, too. If you have worms in your compost you have castings. Thus, you are guaranteed to have soluble nutrients. Not to mention the nutrients that are tied up in the bacteria and fungi that are breaking the material down, the disintegrating bodies of dead worms, the feces of the multitude of other insects and crustaceans (roly polies), etc. Those nutrients are later released/retrieved for plant usage. If compost isn't fertile, my plants sure seem fooled. Nutrients don't magically appear in soil, so they're coming from something despite the fact that I practice fairly intensive planting. I live on a hilltop, so runoff isn't carrying any nutrients to my raised beds. If anything, it's leaching them. The only source of nutrients is the compost. Also, I had a compost bin that started growing a pumpkin plant from it. I was curious so I stopped turning the compost to let it grow. It got humongous and grew fast. Guess someone forgot to tell it that compost isn't good for nutrients. People can argue til they're blue in the face, but the healthy plants just don't lie or care about numbers we attach to what semantics lovers deem a fertilizer despite the actual definition of the word. So, if your goal is to feed plants and increase soil fertility, compost is a fertilizer. If your goal is to write an essay to share with people that don't understand that things which contribute to fertility are fertilizers, call it an amendment.

Adding fresh compost regularly (as opposed to "cured" compost) will feed the worms quite well. In fact, some people compost just to make worm food for commercial worm production. I tell people that raised beds aren't gardens. They are worm bins with plants. Feed those worms and they will do the rest. And just to drive a point home, the worm poop doesn't magically contain nutrients. It's derived from the compost they eat.

If I get a chance, I'll take a few pics of my compost and garden. You can decide for yourself if you think it's fertile and if you'd like info on what I do you can pm me.

Obviously using other feedstocks will contribute other nutrients and various amounts of same.

Lloyd

P.S. click on the "Download PDF" to get the fact sheets through the links.

You are fortunate to have the time and health to expend energy to add small amounts of nutrition to the soil. The OP may or may not.

Far, far more effective is to add fertilizer for nutrition. Just as adding fertilizer for soil tilth is far, far less effective than adding compost.

Dan

'Tilth' is Googleable. I merely turned the topic around to make a point about what is appropriate where. That is: compost is not used for fert, and fert is not used for compost. Just like you wouldn't use jello to pound a nail.

Dan

Good thing this isn't an educational forum, because then we'd have to explain things.

Your compost nutritional value, as has been said by more than one person, depends on content. To those beyond ignorance, it takes about 15 minutes a day to manage a hot compost pile or leave it for every other day. When you understand and instill the value of family in your home, you don't have to be young. You can get help. My son is learning how to compost to help me. Hopefully he will also teach his children and so will my other three kids. I help my grandfather (80). Not fortunate to be young and healthy. Fortunate to be instilled with and continue the tradition of family values and responsibility to elders. The same way it's been done for thousands of years. Of course, some people that don't have family around use these crazy things called tools. I believe one guy in this thread uses a tractor on windrows. I use a rake and fork to avoid having to bend much because I blew my knee out weight lifting years ago. I also have tendinitis. I work for a living and (as I mentioned) have 4 kids. Of course, rather than sit my kids in front of a TV or video game for the evening I teach them things that will come in handy in adult life. And in that teaching we get work done and enjoy the big fruits of our labor. So, don't try to act as if one has to be in peak condition or have lot's of extra time on their hands. That's completely untrue.

Oh, by the way, I meant to say to the original poster that I have yet to use too much compost and I use a lot of it.

So to wrap up for the OP in a few words, compost is used to improve the soil - but not for a good shot of nutrients - and you can't use too much.

Dan

It was worth the $30 to know the nutrient content and also to know that the heavy metal content was very low.

Nancy

Good gardening, Mary

Chemical fertilizers are water soluble salts of NPK. They kill the microbiology in the soil that work to "feed" the plants. The plants can take these up easily enough but if you stop using them the plants suffer because there is a greatly reduced population of microbes in the soil, that is to say, no one left to feed them.

Organic fertilizers are not water soluble and break down slowly - basically they're food for the microbes (bacteria and fungus) that work to feed your plants.

Compost, is extremely rich in soil microbiology. It's main benefit beyond improving tilth, suppressing weeds and regulating moisture is the addition of bacteria and fungus.

Personally I use organic fertilizers and loads of compost in my garden with much success. Look for fertilizers with low NPK numbers - a little goes a long way with an active living soil.

I came to understand that even though compost has a low NPK, it's fertility is actually much higher due to the fact that there are more nutrients in it that just aren't measureable but will, with time and decomposition, be released.

many people do you compost for nutrients and soil building. think about it, how can a plant that is only being fed by compost (which tested .5-.5-.5) appear and perform as well as a plant that is being fed organic or even synthetic ferts???

Dan

I've amended poor,sterile sandy soil with lots of compost and no fertilizers, organic or chem. Everything grew like gangbusters. They must be getting nutrients from somewhere. People underestimate the power of low octane fertile soil.

It must be clarified that if you need nutrients today in your garden to perk up the plants, a few forkfulls of compost likely isn't going to make them leap out of the ground.

Dan

I think anubis_pa is making a very good point, here, and I'm not seeing others talk about it.

I worked about 20 gallons of compost into my 72 sq. foot garden this Spring (which isn't nearly as much as I would have used if I'd only had more available). Even at 0.5-0.5-0.5, I'd need a full gallon of a granulated 10-10-10 fertilizer to get as much N-P-K for that area as the compost...and while I haven't used chemical fertilizers since childhood, I don't recall using the stuff at that sort of volume.

(This assumes that NPK numbers are by volume, rather than by weight, and I can't recall at the moment...but even if it's by weight, we can assume that the numbers would be at least vaguely similar.)

However, we know that when soil analyses are done, they are done on a weight/volume, and may recommend, say, 3 lb P per 1000 sf (vol being covered at depth). If the OP needs 2 lb P for her 1000 sf and she has compost at .5 .5 .5, then that is a LOT of compost to apply.

That is: 100 lb of compost at .5 .5 .5 is 100*.005 = .05 so 100 lb compost at .5.5.5 has .5lb P. So to apply enough compost to make up the deficiency, the OP has to hire a dump truck to bring in enough compost for her 1000 sf garden to make up the difference. A 500 sf garden would need a 1/2 ton truck to haul in, which IME is ~6-8 [.6] wheelbarrows. Hauling in 7 wheelbarrows for 500 sf and turning in should take ~2 hrs with cleanup if you're frisky and young, not counting going to the rental place and back twice. More if you want deeper than a tiller can go. Others can share their experiences turning in this much by hand.

To compare to a three-bin compost system at 4x4x3 per bin, IME this gives you maybe 40-80 lb finished compost in the last bin (willing to hear otherwise).

HTH.

Dan

Yes the NPK is low per 100 pounds. It is not unusual at all for people to apply hundreds of pounds to their garden. Thus the fertilizer value is pretty fair.

Yes you can use too much. I'm a lawn kind of guy and using more than 1 cubic yard per 1,000 square feet is to risk smothering the grass. One cubic yard weighs upwards of 700 pounds. If you are not putting it on a lawn, then you cannot use too much.

joe.jr said,
If compost isn't fertile, my plants sure seem fooled. Nutrients don't magically appear in soil, so they're coming from something despite the fact that I practice fairly intensive planting. I live on a hilltop, so runoff isn't carrying any nutrients to my raised beds. If anything, it's leaching them. The only source of nutrients is the compost.

ValerieRU posted a link a few months ago which goes into this. A Russian soil scientist published a paper in 1900 that put three commonly known facts together that woke me up.
Fact 1: Carbon-rich organic material (including humus and compost) has the ability to absorb ammonia gas from decaying protein.
Fact 2: It also has the ability to absorb moisture from the soil and from the air.
Fact 3: Ammonia gas is highly soluble in water.
With these facts the theory is that the compost absorbs ammonia gas and moisture from "thin air." Then when the air temperature drops below the dew point, that ammonia laden moisture drains out of the bottom of the surface compost providing a fast acting fertilizer directly to the roots.

Simply having humus in the soil doesn't necessary supply available N to plants for assimilation - the reasoning above neglects volatilization and leaching. If simply having various forms of N in humus meant plants could use these forms, we wouldn't have N limitations in many forest or woodland stands, and we wouldn't have had to invent the Haber process to obtain N to deliver to plants.

This is what I meant by the whole of it is greater than the sum of its parts; all of the soil working together is what makes good soil. And why I used the pounds thing with reference to a typical home composting bin - the finished bin does not contain enough weight to deliver sufficient nutrients in my example.

Dan

Equally likely the soil there has better water holding capacity and cation exchange capacity.

Many people here seem to be locked into [a] theory that all that plants need to grow is NPK

I think this is largely a function of product labeling.

Dan

Nope, small patch was as dry and dreary as the rest of the lawn for years.

Thanks!

I just found out today that adding fertilizer to compost makes both work better.

Fertilizer, as is well known, most of the time provides mainly N. P and K reserves deplete far more slowly than N reserves, in virtually any soil. Generally, unless one composted a very brown pile, and the compost is still composting, it will have significant amounts of N. In most cases, 2 inches of the stuff will provide decent fertilization for the year. Cabbages growing on beach gardens excluded.

If you don't know about all the subsequent knowledge gained in the past century about N in the soil, you may want to visit a used bookstore and see if you can pick up a basic soil science book, cheap. Community Colleges often have basic horticulture classes that should cover these knowledge gains as well. Some of this updated knowledge is also found in agronomy classes, forestry classes, agriculture classes, ecology classes, specifically wrt fire and its effects on soil N...if you get the chance, check 'em out!

Dan

Usable N is what one cares about.

And dew not evaporating but being adsorbed is part of the available soil moisture in the solum.

If I were to guess the total amount deposited in the solum, that number doesn't help an argument for...for...um...I'm not really sure for what exactly because there is no acknowledgment of usable N , assimilation, volatilization and leaching, nor why if this idea is so great why N is limiting in so many ecosystems (except where man deposists too much and has upset the N cycle).

Again, plopping some compost in the garden isn't immediately going to give the OP the shot of NPK implied in the original question and not clarified.

Dan

why if this idea is so great why N is limiting in so many ecosystems

Tell me please, where did you find ecosystems with lack of nitrogen?

Most forest ecosystems, many riparian systems (e.g. compare, say, the Tongass riparian with and without salmon), etc.

Nitrogen in dew is present in the forms of HNO3 (nitric acid) and NH3 (ammonia). They bound with soil minerals and form "available" for plants forms of N, P, K, Ca, Mg and so on

Um, no.

Dan

That would be incorrect thinking. I return to my entreaties for purchasing basic texts¹, reading them, and understanding the knowledge therein.

Viz.:

Although forest floor and mineral soil represent the largest pools of N in forest ecosystems, the majority (90 percent) of N contained within them resides in organically-bound forms that are unavailable to plants...[pg 557]

B.V. Barnes, D.R. Zak, S.R. Denton and S.H. Spurr, Forest Ecology (4th ed.), John Wiley and Sons, New York, NY (1998) 774 pp.

This is related, directly, to the assumptions in the replies that imply that the implied OP question can be solved by sprinkling compost from the pile in the veggie garden. This is false, unless 'sprinkling' means 'piling on many inches thick, turning well and waiting'. Soil cannot be improved in a day to provide all the nutrients plants need. It takes time, critters, and organic matter in addition to mineral soil (moisture helps too).

Dan

1 Texts more recent than texts written in the 19^th century.

Dan

Uuuhhh Raaahh! My Mackissic Merry Mac 12pt chipper is on its way now. I have an acre with a lot of trees/shrubs that get pruned. I'll have literally tons of ramial chipped wood.

I did forget to order the 1/2" and 1/4" screens for the chipper, so I'll have to jump on that.

It’s true ... and not true...
They are unavailable to plants but they are available to microbes and after them are available to plants.
Add this book to your library: "Krasilnkov. Soil microorganisms and higher plants" .
You may trust him. His portrait is hanging on the wall of fame at Luis Pasteur institute in Paris.

idaho_gardener,
you are a lucky man!

That is: again, many terrestrial ecosystems are N-limited, due to the processes that I mentioned several times upthread.

BTW, one of the outcomes of the FACE studies is that increasing atmospheric CO₂ will not "feed" forests that are N limited (many of them are, esp 2nd growth), so forests likely cannot be counted on as a carbon sink for management schemes to mitigate man-made climate change.

Dan

Essentially. If there were topsoil the results could be better.
Those ecosystem is too young and thus it may have nitrogen deficiency. If we are talking about good established ecosystem, in aged pine forests there are many ferns which provide nitrogen to soil. It’s enough for trees with 1 meter in diameter.

Dan

Thanks for your reply! Bye now!

Dan

Val, yes, I am a very lucky guy. Now, if only that chipper would arrive. Instant gratification takes too long.

Dan

I used to investigate aircraft accidents and had an unfortunate opportunity to work in a field of wild plants adjacent to a farmers corn field in South Carolina. The corn field was sand and the field I was working in was 15 feet deep of peat and then the bed of sand started. These two fields were 30 feet away from each other. Back then I had no interest in the soil but I sometimes wonder about what I was seeing. The airplane punched a very clean hole into the peat and stopped abruptly when it hit the sand. The resulting jet fuel fire burned away most of the top growth making our work very easy but it would have been similarly easy for a soil scientist to really look into that situation. It would not have exactly made lemonade out of the very sad situation but maybe some good would have come of it.

Also, huge thanks to Dan and to Valerie for keeping the apparent disagreement/agreement civil. Realizing that this thread is modestly adrift from the original intent, y'all have made the best of the drift.

It's back to availability, immobilization and what I wrote above: Simply having humus in the soil doesn't necessary supply available N to plants for assimilation - the reasoning above neglects volatilization and leaching. If simply having various forms of N in humus meant plants could use these forms, we wouldn't have N limitations in many forest or woodland stands, and we wouldn't have had to invent the Haber process to obtain N to deliver to plants.

The first link in my multi-link reply yesterday goes right to a page that details this issue and additional reasons why N may be unavailable.

Dan

Thank you very much for your story about 15 feet of peat over the sand. It’s very instrucrive story! Your remark about keeping agreement/disagreement civil led me to the thought that civilization is exactly the line between agreement and disagreement. Very nice!

Dan,

That book in your link is interesting. I’ll read it when I have time.
At this moment I have opened it on the page you have linked, and what I see?

Other elements that limit nitrogen fixation include molibdenum, iron, and sulfur which are essential cofactors of nitrogenase. Pasture legumes are limited by molibdenum in parts of Australia, foe example due to low level of molibdenum availability in the highly weathered soils, particularly at low pH. ... Phosphorus, iron, sulfur or molibdenum, may, in these cases, be the ultimate "master element" that limits production, even though nitrogen is the factor to which primary production responds most strongly in shirt-term experiments.

If so, why we have to speak about N limitations if real limitation is Mn (molibdenum)?
I know about molibdenum. I very well know about molibdenum.
Do we have to start costly Haber-Bosch process and cart tons of nitrogen fertilizers here and there, year by year, across continents and oceans, or we may just spread out few grams of molibdenum over hectares for 100-1000 years? Or we can shift pH to make molibdenum available and begin the process of nitrogen fixation. We have to solve real cause of problems instead of offering evasive and temporary solutions.

For me soil is an edge between lithosphere and atmosphere. Since atmosphere has 70% of nitrogen, for me soil will never have N limitations by definition. (If just only nitrogen will be removed from air by Haber-Bosch process.) :-)

Dan

If you're tired of reading the posts on a topic, you can simply stop clicking that topic.

Dan

Al