kimmsr:
I test my soil every 4 years on the "Test, don't guess" principle. But I often have second thoughts, simply because all soils are different, meaning you can get away with something in one garden that wouldn't work in another. I wonder if I'm gardening to produce a nice soil test as Arden Andersen would say. Which brings me to this: shouldn't we be testing the produce, especially since the name of the game is (should be) to produce nutrient-dense food? I use a hand-held refractometer to measure BRIX, and this year I shall be using a device to measure pH in leaf sap. I would really appreciate your thoughts on measuring food quality ass opposed to soil quality. Regards, Peter.

Peter, tissue testing is CRITICAL when one is trying to find certain answers. It's used all the time, routinely, in agriculture and agronomy.

It's the only accurate method of determining plant deficiencies and toxicities, for example. But tissue testing can determine the actual nutrient quality of the finished product. And since every soil is different, tissue samples can help a grower really and truly fine-tune a fertilization program.

I've used tissue sampling many times for diagnostic purposes, and always kicked myself afterwards for not making the process a routine part of a field call. And if one is very interested in the nutritional content of the fruit, veggies, or grains they are growing then it's the only method of gaining that information.

Of course, it doesn't answer all of the questions we may have...and this kind of testing is probably not needed for the average backyard grower.

As far as testing for Brix and sap pH, I've assumed for quite some time that if growers knew how to manipulate these two qualities within their plants, than many plant problems will be prevented. This IS something that can easily be done by anyone with the proper tools.

I'm of the "What I do works for me year in and year out" mentality. If I had soil and plant issues, then I'd test. New gardners, new/different soil, not enough compost to solve problems? Then I recommend testing. (and hey- test all that you like if it's working for you).

I also only use rabbit manure, rather than inches of cow manure- thus avoiding many of the pollution issues associated with certain organic practices.

for me it's don't worry about it unless there is an obvious problem, and that has only ever occured once with one tree i planted.

we don't use fertilisers and rarely use manures relying on green hay mulches and kitchen scraps to feed our gardens, and so far after about a decade no problems. figure if you get all the worms and organisms working in the soil there can't be too much wrong with it hey?

len

Here is a link that might be useful: len's garden page

I support pablo's philosophy - if it's working well, don't look for trouble :-) But that's the approach I take in my garden, where I've lived for many years, know what's in the soil (cuz I put it there) and have experienced no significant problems that makes testing a necessity. And I do not routinely use fertilizers, preferring to just mulch with compost and use the bunnies' leavings on those plants I know have high nutrient demands.

But I do support the need for soil testing for the same reasons he advocates - unfamiliar soils, novice gardeners or those who feel the need to fertilize on a regular basis or who are experiencing evident growth problems.

And as an aside, I'd like to take exception to the notion that organic gardening is somehow the pervue of only those who grow edible crops. Organic (or "natural" if you prefer) gardening is a philosphy that applies to any type of gardening and is not restricted to cropping or edible gardening. It is just as valid and important to apply those same principles and practices to all gardens, even my 99% ornamental garden.

Good point, gardengal. All of my tissue testing experiences were related to the turfgrass on golf courses, or for ornamental plantings.

Do I do such sampling in my own yard? Nope.

Having your soil tested is not looking for trouble it is done to ward off trouble, save you money in the long run, and aid in preventing environmental damage.
No one can look at their soil and tell which nutrients are there. No one can look at a growing plant and tell if it is strong and healthy unless the plant is covered with insect pests and if that is the case which of the twenty or more macro or micro nutrients are lacking that causes that problem, or is it because you added something that was in abundance, was not needed, and is now preventing your plant from uptaking other, necessary, nutrients.

I beg to differ. If one has the experience, the training or the resources, it is very easy to determine most common nutrient deficiencies by looking at plant appearance and performance. There are scores of texts with pages of illustrations and descriptions that will narrow down plant problems to specific nutrient deficiencies or over concentrations. While these may not be 100% absolute without testing to confirm, it is certainly a good starting point from which to proceed.

I do believe there is a tendency to want to overcomplicate gardening. While I am not dissing soil testing by any stretch of the imagination, it is often simply not necessary to do on a routine basis. If one has taken the time to build a healthy, organically rich soil and to continue to amend it over time with a quality organic mulch like compost, virtually all necessary plant nutrients, both macro and micro, will be present in sufficient quantities and adequately replenished as needed to ensure ongoing plant health. We seem to think we can outsmart nature by our continuing manipulation of the environment when in fact we should be following more of Ma Nature's guidelines in attending to our soils and our gardens. Back off on the fertilizers, mulch with organic matter, stop attempting to micromanage your garden and see what happens. I defy anyone to visit my garden and not confirm the health of my non-fertilized, non-soil tested plants.

How much more simple can it be, how much more money can be saved and how little adverse impact can we have on the environment if our routine tending to our soils and gardens relies primarily on composting and using that compost to mulch and amend? IMO, fertilizing is highly overrated and most often unnecessary for any but high cropping or container situations.

i'm also with gardengal,

on this one, and i also ask anyone to look at my plant pic's and tell me the plants are less than healthy, or if you want to hop a jet you most welcome to come and look see for yourself. i'll give you a cold glass of water and vegemite sandwich chuckle.

i have only ever tested when it is obvious something is wrong and remedies are not working.

we also don't add man made fertilisers as a matter of course preffering the range of natural nutrients found in green hay mulches.

len

Here is a link that might be useful: len's garden page

I would agree with not testing, in part - after 10-15 years of gardening with lots of organic matter of various types mixed in, you should have very good, healthy soil. And after 15 years, your garden soil should be in balance - IF you got a test in the first place and added what was lacking. Of course, after more than 10 years of adding a good mix of organic matters, your soil SHOULD be in great shape. BUT, for those of us who are starting out with untouched soil - mine used to grow row crops, then was pasture/neglected, then had umpty-ump game cocks penned on it, before I started to garden it - the house/flower gardens were pasture before the house was built - do need to have the tests done for a while, just to be sure that we have added the correct things. While I HAD gardening experience before I moved to SC, it was in very different climates and soils, so knowing from experience what to add had to be learned again. I am thinking that I will have another test done this year, because after 2-6 years, depending on what part you are looking at, I want to be sure I have been adding the right amounts of what is needed to my red clay - I DO know it is better soil, but I had enough problems with disease last summer to think something isn't in balance.

SO, I think all of you are correct, in your own places.

Do you have problems with insect pests and plant diseases? Those are related to plants not as healthy as they could be with a good healthy soil.

The only home test that is available to me here is the Rapitest pack with 4 vials - one each for pH, N, P and K. Since they're quite expensive, I have so far only tested the soil from one part of my garden, under the hibiscus bushes. The results were:

pH-neutral, N-low, P-high, K-low

How accurate are these home tests as an indicator of soil deficiencies (I'm assuming that they only test for soluble nutrients)? Should I start reaching out for N/K fertilizers, or just continue composting, amending and spinning a healthy soil food web?

My personal suggestion for anyone who regularly adds appreciable amounts of organic matter to their soil is forget what the tests say regarding nutrients.

There are labs that will test for all nutrients rather than just readily available forms, but I couldn't tell you off hand which ones those are or what the cost is. I do know that the extension service in my state does not test for all nutrients.

If one is growing perennial plants such as shrubs or plants capable of naturalizing in one's area there will almost never be a need for any fertilizer and even a regular organic matter addition may produce higher than needed fertility for them, particularly the 'wild flowers'.

For plants grown for foliage there is also probably no need for fertilizers.

Where the need for fertilizers becomes more a concern is with plants grown for blooms or fruit/veggies and certainly anything grown in containers.

While these plants may grow just fine in soils well amended with organic matter, it is also possible one will get a better yield with supplementation. It is also possible one will get the plants sick/diseased by over doing it.

I don't have a perfect solution to this, but what I will be trying this year is growing everything without fertilizer in the soil (just compost, and lots of it) and I will be on standby with water soluble fertilizers like fish/seaweed emulsion and if necessary, DynaGrow/DynaBloom (not organic). These will be applied as a foliar spray to a portion of the plants if I suspect they could use a boost. This way I can see the difference between the fertilized plants and the non fertilized.

>justaguy2
I was just going to ask you how it is possible to maintain rapid, year-round growth (in the tropics) without the use of fertilizers. Then I realized that nature has been doing it for millions of years in our forests. So I suppose that the ultimate objective is to provide plants with the natural conditions found in those ecosystems, and use fertilizers to correct deficiencies only when necessary.

OK, this may be a silly newbie question, but I haven't really been ammending for long enough to actually observe it:
I just noticed that my planting beds are filled to the brim with compost and manure mulches. Do these really "sink" over time, and is that an indication of when to add further ammendments? Even if I made some compost now (which I was planning to) I wouldn't have any place to er, put, it. Though I could just make teas, of course.

Through physical and biological decomposition, and the on-going tilling done by an army of macro organismns such as earthworms, your compost and mulch really and truly end up as the simple atomic elements that will be taken up by your plants.

insect pests and plant diseases aren't much of an issue in my gardens, the only pests we look for are grubs and catterpillars and you get those from egg laying moths/butterflies, but it is only ever likely to occur on occassions on the brassicas.

len

I never tested, assuming I did enought with adding compost, kelp meal and some lime to combat acid rain. Then one year I got tomato blossom end rot (boy did I cry). I tested soil and found it was too low in calcium. Now I add more lime to soil, and save all my eggshells crushed in plastic bag in freezer. When I plant tomatoes, I put crushed eggshells in holes. See link below.

Here is a link that might be useful: more about blossom end rot

Those home soil test kits are notably unreliable. Many people here who have tried them found the pH test often gives the same results whether you test your soil or vinegar or a baking soda solution and those kits do not tell you why your soils pH is what it is. Nitrogen availability depends on soil temperature, the activity of the Soil Food Web, the warmer the soil the more active they are the more N will be available and those test kits are based on junk science anyway testing only N,P,K when there are many other essential nutrients your plants need, Magnesium, Zinc, calcium, Iron, Sulfur, Boron, Copper, Manganese, and Molybdenum are some that can create problems if they are in too short supply or are not in good balance.
Blossom End Rot while cause by a Calcium deficiency in the plant can happen in plants with adequate soil Ca levels. Adding egg shells to the planting hole will do nothing to prevent BER this year since the Soil Food Web will not make that Ca available to the plant for quite some time, and if your CA and Mg ratios are out of order what Ca you do have may not be available to the plants.
You will not know that unless you have a soil test done.

I garden for many reasons, and harvest is not always my first priority. Therapy is often a prime reason and I am happy to work with one soil as another, for the therapeutic value. Being physically active, in the sun, making a disorderly piece of land look more attractive, is good, period. The process makes my brain happy.

And like most of the other people who have responded, my garden is generally productive and healthy.

I'd like to see a reference that insect pests do better on "weak" plants. I have a butterfly garden, and the lush plants host the most caterpillars.

I'm not against testing either - and it would be fascinating to have all of us "live and let live" long-time organic gardeners send a soil sample to the extension service, to see if our hunches (that our soil is in relatively good shape) are borne out.

The argument that soil testing might reduce pollution carries the most weight with me, as fertiliser runoff (chemical *or* organic) has negative effects on the ecosystem.

patty, one of the great benefits of organic fertilizers is that runoff or leaching into groundwater is seldom an issue. The reason is that most organic fertilizers (and certainly those in granular or powdered form) are not water soluble - it takes the activities of the soil organisms to covert them in to a plant-usable form so they will persist in the soil until digested, not moving through it like synthetic, salt-based solubles. This applies to ferts only - compost and manures can and do leach and a good deal of rural pollution of groundwater is attributed to leachates from these materials.

While it is not the only cause, plants under stress for whatever reason - drought, over fertilization, poor soils or drainage, diseases, etc. - emit pheremones and other intangible attractors that certain insects are drawn to. It is not necessarily weak plants that attract predatory insects - very lush growth can do so as well. And planting a garden that is attractive to specific insect types (and I use that term loosely), like a butterfly garden, should be of no surprise when those insects colonize. The health, or lack of it, of these types of plants is not a factor, it is the plants themselves. This is the underlying theory that supports companion plantings, afterall.

Gardengal it is not necesarily true that leaching or runoff of organic matter in the soil is seldom an issue, it depends on many factors. The nutrients in manures are often soluble enough to flow out if the soil and any of the "Organic Fertilizers" that have those numbers on the label are also soluble enough to flow right out of the soil. Those numbers are simply readily available nutrients, water soluble nutrients.
But too much organic matter in the soil can also present problems. People that live on the edges of swamps see this in the well water all the time, a smell and taste caused by rotting vegetation in the water.

kimmsr, I tried to make it very clear that I was not referring to composts or manures. These are not technically considered organic "fertilizers" as they do not have a guaranteed analysis. Organic fertilizers that are marketed and sold as such and have a guaranteed analysis and a stated NPK ratio and are granulated, pelletized or powdered are by nature NOT water soluble, therefore they do not move through the soil nor infiltrate groundwater. The nutrients are not present or accessible to plants until after digestion and/or assimilation by soil organisms.

When you test for a nutrient and get a number, required by the USDA, you test for "readily available", ie. water soluble nutrients. Nothing can be sold as a fertilizer in the USA unless it undergoes those tests and the nutrients, whether it is an "organic fertilizer" or a synthetic are water soluble. The nutrients measured in manure are readily available adn water soluble. Compost can only be sold, in the USA, as a soil amendment, not a fertilizer, becuase the nutrients in compost are not readily avialable and are not water soluble.
Because many of the nutrients in manures are water soluble is why in the Netherlands you can only apply a certain amount of manure and why the soils in the Netherlands must be tested before that manure can be applied.

That is not precisely true.

From a Texas A&M University article titled "Organic Fertilization":

"Personal beliefs often enter into the selection of a fertilizer with many individuals choosing to use organic fertilizers rather than manufactured products. Both types of fertilizer can be used to supply soil nutrients to the plant, but with few exceptions, natural or organic fertilizers contain nutrients in low concentrations and relatively insoluble forms as compared with synthetic fertilizers. The concentration and solubility of the nutrients govern how much fertilizer to apply because the nutrients must be dissolved in soil water before they can be absorbed by plants.

Nutrients in organic fertilizers become soluble through a process termed mineralization or weathering where the complex molecular structure is broken into smaller water soluble mineral ions that can be utilized by the plant. Some organic substances have a rapid rate of mineralization and release all of their nutrients during the first growing season with little to no residual value for crops in subsequent years. Other organic substances have a slow rate of mineralization and release portions of their nutrients over several years and may be considered soil building materials. Materials slow to mineralize generally have limited value for growth of plants in the year they are first applied. Some natural rock materials that are very slow to weather may have little value in supplying nutrients to a crop or in enhancing the fertility of a soil."

Reaching out and grabbing a part of a piece on why gardeners should not use organic fertilizers does not prove any point.

Gosh, I feel like I'm flogging a dead horse, but in an attempt to try and broaden your rather narrow view here goes:

1. The article is an essay explaining what organic fertilizers are and how they work. It neither promotes them or disparages them. It leaves it up to the reader to make a choice based on information and suitability for their purpose.

2. This article (and a good many others, if one bothers to look for them) states simply and clearly that organic fertilizers - plant nutrients derived from naturally occuring sources (various grain or seed meals, rendered animal/poultry byproducts, plant extracts, minerals and rock powders) - are mostly insoluble in their natural state. That is, they do not readily or easily dissolve in water, either before application or by mixing with available soil moisture once in the ground.

They require the activities of the soil organisms and/or the mineralization described above to break them down and convert them into their basic elements, which are then able to be accessed by plant roots. This is what makes organic fertilizers uniformly "slow release" compared to synthetically derived ferts. This is both a blessing and a bother, depending on how rapidly one wishes the effects of the fertilizing to be realized. "Slow release" can be translated almost directly to "water insoluble" - even synthetic fertilizers that have been prilled, coated or otherwise treated to be slow release are unlikely to cause significant leaching as the breakdown of the material coating the product is gradual and highly dependent on time, temperature and available soil moisture. Liquid organic fertilizers - typically derived from fish and emulsified plant extracts - have short circuited this process to some extent in that they have been prepared into solution. This is not the case with granular or powdered organic fertilizers.

3. Because of these inherent properties, organic fertilizers - not compost, not manure, not untreated synthetic ferts - do not leach into groundwater readily or easily. It is simply not in their make-up to do so in their applied state.

I am not trying to make any point. I am simply restating rather well established chemical properties in an attempt to clarify what appears to be a misunderstanding of how these products work

Here is a link that might be useful: the full Texas A&M article

GardenGal.. HI!!...being a Texan I love the TAMU site and have read that article before...it's a great educational website and worthwhile continued viewing with an awesome search engine to find anything you want to know!!..You are right on !!...Jeanne

Gardengal I have read that article, numerous times, and it is an apologist attempt to dissuade people from using organic methods of feeding the soil.
I do not have a very narrow point of view but I do have an organic point of view and will maintain that since over 30 years of experience and 50 years of learning have taught me what to do. If you build up your soil into a good healthy condition you will not need "fertilizers" and your plants will grow strong and healthy and will see many fewer insect pests and diseases, and that you cannot build your soil into something good and healthy with "fertilizers".

If you have read the article "numerous" times, I find it very difficult to understand how you could possibly get the notion that it was attempting to dissuade people from using organic methods. What exactly in it lead you to that conclusion? Was it the portion that said that in growing crops, at times the soil may not satisfy the nutrient requirements of the crops and after viewing plant performance and evaluating soil tests, the grower may elect to supplement with fertilizers, organic fertilizers being one alternative? Or was it this excerpt that outlined the values of adding organic matter: "The application of farm manures, composts, or plant residues to meet the nitrogen requirements of a crop will satisfy the calcium, magnesium, sulfur and most of the minor element requirements of the crop"?

I am not a huge proponent of supplemental fertilization in most cases, as I too believe a fertile, organically rich soil, replenished regularly with organic matter in whatever form, will generally supply all that is necessary for healthy plant growth and that fertilizers, whatever their source, are often applied unnecessarily. However I also understand that in some cases, often associated with the annual cropping of edible plants, it is difficult to keep up with the strong nutrient demands these types of crops have without supplemental fertilization. No one is disputing how to arrive at good soil conditions but sometimes they are simply not enough. And why not opt to go with organic fertilizers if that is the case? This article makes no argument against them - rather, it explains how they work, differently from synthetics.

Be that as it may, my point in referencing this article was not to defend using or not using organics or to advocate using fertilizers in place of proper soil preparation. It was to point out the innaccuracy of your statement that organic fertilizers were water soluble and have the same ability to leach and contaminate groundwater and contribute to pollution as do synthetics. And that is simply not correct.

And despite your protests to the contrary, from your writings here on GardenWeb I believe you do indeed have a rather narrow point of view, either not understanding or choosing to ignore the larger picture. Yes, developing a quality soil is the basis for good plant growth. But not all gardeners have the ability to prepare and use their own compost or can even generate sufficient quantities or organic matter to supplement their soil's needs. And farmers and growers involved in intensive cropping often simply cannot keep up with the nutrient demands of their crops without supplemental fertilization. Is this wrong? No, it is just a different approach with typically equally successful results. To dismiss it out of hand because it differs from your opinion IS a narrow point of view.

>kimmsr and gardengal

I'm not going to take sides here, since you two are surely far more experienced. But here's what I understand, from an objective newbie's point of view:

The NPK rating of any fertilizer measures the percentage of *water soluble* nutrients. So, in a 10-10-10 synthetic fertilizer, those numbers are *all* it has to offer since it is essentially plant junk food. On the other hand, pelletized chicken manure rated at 5-5-5 may have significantly more nutrients than what the numbers indicate, since the NPK rating does not measure the insoluble portion of the fertilizer.

So, as kimmsr mentioned, leaching/runoff *could* be a problem when using organic fertilizers. However, due to their low *soluble* nutrient content, it's probably not too big an issue unless they are applied excessively.

P.S. If someone could please answer my question about having "too much" organic matter in the soil :)

Also, to add my 2-cents worth to the discussion, many people are just starting out and do not HAVE the benefit of "good, healthy soil" at the present moment. They may be doing their best to get to that point, but until they get there, they and their plants do need some help. Thus the continuing discussion of organic fertilizers, to give the plants a boost through until they get "good, healthy soil", and don't need anything more.

If you (anyone) have been gardening in the same place for over 15, or even 10, years, then you should have a "good, healthy soil" at the end of that time. But, I am willing to bet that at the 2,3 even 5 year mark, your soil was nothing like that, especially if you started with really bad soil, as many of the posters here are doing. It isn't easy to turn the typical soil found around a newly built house into "good, healthy soil", since what you are usually starting with is probably subsoil with a thin skim of topsoil over it, if you are lucky.

Keeping OM in a pure sandy soil in intense heat is almost impossible - the microherd eat it almost as fast as you put it in - so unless you have access to unlimited amounts of compost, etc., you can't keep your soil as "good, healthy soil", fit to grow a lot of things. If all you want to do is grow those things that DO like those conditions, then yes, you probably do have "good, healthy soil".

I will also add that the definition of "good, healthy soil" changes with what plants you want to grow in it - the same soil that is perfect for nasturtiums is not the same as grows good tomatoes or corn, nor is it the best soil for blueberries. And the best soil for blueberries grows lousy lavender. If anyone has had the misfortune to plant melissa (lemon balm) or Eupatorium coelestinum (wid ageratum) in good flower-garden soil, they have probably been sorry by the next year as they struggled with shoots going 1-3 feet out. But, plant either in relatively unimproved soil, and they are very nice, non-thuggish plants. The best soil for them, as for any plant, depends both on what YOU want to have and to grow, and on the plants' needs.

Sorry to post a follow up to my own message, but I believe that I made some mistakes in my previous comments.

From the Wikipedia:
"The mass fraction (percent) nitrogen is reported directly. However, phosphorus is reported as phosphorus pentoxide (P2O5), the anhydride of phosphoric acid, and potassium is reported as potash or potassium oxide (K2O), which is the anhydride of potassium hydroxide. Fertilizer composition is expressed in this fashion for historical reasons in the way it was analyzed (conversion to ash for P and K); this practice dates back to Justus von Liebig (see more below). Consequently, an 18-51-20 fertilizer would have 18% nitrogen as N, 51% phosphorus as P2O5, and 20% potassium as K2O.

In general, the mass fraction (percentage) of elemental phosphorus, [P] = 0.436 x [P2O5]
and the mass fraction (percentage) of elemental potassium, [K] = 0.83 x [K2O]

(These conversion factors are mandatory under the UK fertilizer-labelling regulations if elemental values are declared in addition to the N-P-K declaration.)
An 18−51−20 fertilizer therefore contains, by weight, 18% elemental nitrogen (N), 22% elemental phosphorus (P) and 16% elemental potassium (K)."

Example NPK analysis of 10-52-10 (synthetic) fertilizer:

Guaranteed Minimum Analysis
TOTAL NITROGEN (N) . . . . . . . . . . . . . . . . . 10%
Nitrate Nitrogen . . . . . . . . . . . . . . . . . . . NONE
Ammoniacal Nitrogen . . . . . . . . . . . . . . . 7.6%
Urea Nitrogen . . . . . . . . . . . . . . . . . . . . .2.4%
Water Insoluble Nitrogen . . . . . . . . . . . . .NONE
AVAILABLE PHOSPHORIC ACID (P2O5). . . . .52%
Soluble Phosphorus (P) . . . . . . . . . . . . . .22.6%
Insoluble Phosphorus . . . . . . . . . . . . . . .NONE
SOLUBLE POTASH (K2O) . . . . . . . . . . . . . . .10%
Soluble Potassium (K). . . . . . . . . . . . . . .8.3%

Therefore, as I understand it, NPK ratings are a measure of *both* soluble and insoluble nutrients (as opposed to what I wrongly stated earlier). Of course (as in the example above), the nutrients in synthetics are all water soluble. If only I could find a similar analysis table for organic fertilizers. Then we would be able to how much (if any) of it is water soluble.

My second mistake was posting that last "P.S." part in the wrong thread. I got my windows mixed up and asked for help here instead, when it should've been in the "ideal % of organic matter" thread. Sorry :P

Let's clarify something:

The NPK numbers stated on any fertilizer refer ONLY to the guaranteed analysis of those nutrients in the bag/package. A 10-10-10 bag of fertilizer will contain 10% nitrogen, 10% potassium and 10% phosphorus. The rest of the contents may contain micronutrients or trace elements but the majority of it will be fillers. Therefore, a 40# bag of this fertilizer would contain only 4# each of the three primary nutrients. The NPK designation has absolutely nothing to do with how much of the product is immediately available or is water soluble - a 10-10-10 treated slow release synthetic fertilizer will have virtually none of its product immediately available and its solubility is only present and active once the protective coating has fully dissolved, something that can take as long as 12-14 months with certain formulations of Osmocote Plus. If not treated to be slow release, chemical fertilizers ALL tend to be immediately water soluble - that's because they are comprised almost entirely of soluble salts that can be immediately accessed by plant roots. Hence the issues with fertilizer "burn" if applied excessively or incorrectly and the problems with these types of products leaching or moving rapidly through the soil to infiltrate groundwater.

Some chemical fertilizers contain different sources of nitrogen which have varying degrees of solubility, These are typically spelled out on the packaging as well and will indicate how much of the nutrient is determined to be "immediately available" - this is very different from the NPK guaranteed analysis, however.

Similarly, a single ingredient organic fertilizer like alfalfa meal with an NPK of 2-1-2 contains 2% nitrogen, 1% phosphorus and 2% potassium, the rest being micronutrients and organic fillers. And virtually none of it is immediately water soluble nor is it immediately available. Organic fertilizer are not comprised of soluble salts - these salts are not formed until after processing or decomposition by soil organisms or by mineralization or chemical reactions with the soil. Therefore, there is virtually no risk of fertilize burn when using these products and minimal chance of leaching.

Organic fertilizers, like the alfalfa meal or various blended formulations, are considered low analysis fertilizers as they all tend to have lower concentrations of these 3 nutrients compared to synthetics or chemical fertilizers, most of which are considered high analysis fertilizers.

Various animal manures and compost, while they do have nutrient value, are typically not considered fertilizers as their nutrient levels are variable depending on source, feed and processing methods and seldom come with a guaranteed analysis. Legally, unless the guaranteed ananlysis is stated on the package, they cannot be marketed or sold as a "fertilizer".

I hope this serves to clarify some apparent misunderstandings about the information contained on fertilizer labels and how they work.

I am personally embarrassed by TAMU's limited knowledge of organic farming and gardening. The article linked above is just one example. And I agree with kimmsr that the article is just one of many that try to disuade people from using organic materials. Here's why. The statements below in italic are from the TAMU site...

Both types of fertilizer can be used to supply soil nutrients to the plant, but with few exceptions, natural or organic fertilizers contain nutrients in low concentrations and relatively insoluble forms as compared with synthetic fertilizers. The concentration and solubility of the nutrients govern how much fertilizer to apply because the nutrients must be dissolved in soil water before they can be absorbed by plants.

By saying organic fertilizers are low nutrients compared to chemicals. The implication that the only nutrients in organics are the limited soluble ones shows a fundamental ignorance of the biological process which release the insoluble nutrients.

Some natural rock materials that are very slow to weather may have little value in supplying nutrients to a crop or in enhancing the fertility of a soil.

Once again saying you are better off using chemicals and ignoring the fact that microbes will "weather" the rock into nutrients.

In the fertilization of crops, growers must first be concerned with supplying the primary macronutrientsnitrogen, phosphorus and potassium. Since organic or natural fertilizers have variable chemical composition, a balanced or adequate supply of all of the primary macronutrients from one organic fertilizer is unlikely. Therefore, more than one kind of organic fertilizer is usually needed to provide sufficient crop nutrition in any system of organic gardening. This situation differs from that of synthetic fertilizers that are manufactured to contain from one to all three of the macronutrients and can be purchased in practically any formulation.

Implying the manufactured synthetic fertilizers are better because one organic material does not provide 100% of the soluble nutrients to the plants. Nevermind that there is no single synthetic chemical that will provide 100% of the nutrients either and they they have to blend just to get three of the 13 or so necessary nutrients.

The nitrogen in organic fertilizers such as dried blood, alfalfa meal and seed meals is released almost entirely in the first season they are applied to the soil, leaving little residual nitrogen available for the following season unless the application was in excess of the requirements for the crop.

Does this sound like a positive statement to encourage you to use organics? How about this statement to go along with the former: Synthetic fertilizers are salts which wash through the soil with the first rainfall or irrigation; thus, they have to be replaced continually throughout the growing season.

Rock phosphate, mined from deposits, has a high phosphorus analysis, but the material is of such low solubility that special application techniques are required to achieve any benefits in the soil. Colloidal rock phosphate, taken from a lower grade ore than regular rock phosphate, is claimed to release phosphorus more readily than regular rock phosphate. Although colloidal rock phosphate costs the same as regular rock phosphate, the phosphorus content is only about 2/3 that of rock phosphate. The low pH of the soil helps release the phosphorus from the phosphate source. Super-phosphates are manufactured by treating rock phosphate with sulfuric or phosphoric acid, simulating the action of acid soil on the rock. Unless restricted by marketing or philosophy, organic growers may want to use the super-phosphates during an initial build?up of phosphorus reserves in the soil. Once a soil test indicates an adequate level of phosphorus, organic materials can be used to maintain phosphorus fertility.

This statement illustrates the colossal lack of information in the TAMU system about organics. Taken without the understanding of the microbial processes involved, the TAMU statement basically drives the user to using chemicals. And keeping in mind that Texas is famous for alkaline soil, the statement from a Texas school that low soil pH will bring out the phosphorous is just weird. Our soil pH runs in the 8s but we still grow things. Why? Because soil microbes produce acids to reduce the minerals into forms the plants can use. Some of the unused acids will persist in the soil in the form of humic acid.

I realize this topic is straying from the intended mark, but at least the originator has had a hand in it. I am not big on soil testing, which is why I've avoided this thread, but I had to check in to see why it has been bouncing to the top so much.

I'm speechless! I don't see how anyone can read negative 'implications' into that article whatsoever!

Those were my thoughts as well, Dorrie, but I guess it is all a matter of interpretation :-) For example, my impression of this statement that was singled out: "Synthetic fertilizers are salts which wash through the soil with the first rainfall or irrigation; thus, they have to be replaced continually throughout the growing season" was that it made a rather compelling argument FOR choosing organics over synthetics. You wouldn't need to fertilize nearly as often and you'd avoid the leaching problem.

It is not the most detailed treatise on organic fertilizers I've read, I'll grant you that, but it covers the basics. And as the land grant agricultural colleges go, TAMU has a very good reputation for promoting organic methods, trailing behind UCDavis and WSU.

dibbit said, "Keeping OM in a pure sandy soil in intense heat is almost impossible". Not true. Most people throw away more organic matter than they add to their soil. Organic matter is there and available without purchasing peat moss from a store except in a very few places.
enoughcliches wanted to know, "can you add to much organic matter to your soil?" Absolutely. Many people do live where there is too much OM in the soil and their water indicates that with taste and many other problems. Often you can smell in the water this "too much" organic matter as well as taste it. Most of the time this will be around bogs, swamps, wetlands. However, for most of us the problem is getting enough, not too much organic matter in our soils.

Kimmsr, I should have added to the comment you cited, that it is almost impossible without constantly replenishing it. If you keep adding OM, it will be there, but if you add once and once only, it will be almost "used up" in a summer. This based on admittedly limited experience of 3 years in FL.

For example, my impression of this statement that was singled out: "Synthetic fertilizers are salts which wash through the soil with the first rainfall or irrigation; thus, they have to be replaced continually throughout the growing season" was that it made a rather compelling argument FOR choosing organics over synthetics. You wouldn't need to fertilize nearly as often and you'd avoid the leaching problem.

Hee, hee, hee! I made that one up as an example of what they might have said if they wanted balance in the discussion.

And as the land grant agricultural colleges go, TAMU has a very good reputation for promoting organic methods, trailing behind UCDavis and WSU.

Please, if you have any links that would support this, please post them. The general feeling here in Texas, San Antonio in particular, is that TAMU is 100% dead set against organics in agriculture. I have one link that purports to advance the organic lifestyle but it is woefully short on substantial content. I'm still looking (in my spare time).

If that is the general consensus of San Antonio..then you are incorrect to say the least...TAMU is one of the leading Agricultural Colleges in the USA and does have extensive information on IPM..as well as organics..you should have clicked on the bottom links of the page you suggested...or do a search on their site...Jeanne

Jeanne, I clicked all the links and did the search. I'm still drawing a total blank. ANY help would be appreciated. If you can show me even basic information on organics, I'll admit I'm incorrect. Extensive information is what I found here. TAMU has nothing like that.

IPM is just about the antithesis of my type of organic gardening. They advocate using organic poisons and THEN using synthetic poisons. My type of organics is to use food sources to improve the health of plants so the plants will resist the pests. Oh, but first you have to have the right plant in the right soil in the right zone at the right time of year. In other words, if you try to grow tomatoes in Alaska during the winter, don't be surprised if they don't do well, get a disease, or get eaten by some kind of snow aphids.

So in all this discussion I have really not seen anything that refutes what I said at the beginning,
1) So you know the base nutrient and soil pH levels.
2) So you do not add "stuff" to your soil that it does not need, but that you do add "stuff" to your soil that it does need.
3) So you do not add to the pollution of your environment.
4) So you do not spend money on "stuff" you do not need.
5) So the yields from the garden are really optimal and the plants you grow are not bothered by insect pests that are more attracted to plants under stress or that are unhealthy because their diet is wrong.
http://www.basic-info-4-organic-fertilizers.com/whysoiltest.html

Many people seem to "feel" that soil testing is unnecessary but there are no real good arguments to support that "feeling".

Many people seem to "feel" that soil testing is unnecessary but there are no real good arguments to support that "feeling".

That's me. Although I have been ripped off with my local garden shop. I sent them a sample of compost. The results said I was low on organic matter and and the pH was way too high. My area is limestone rubble, so what they did was "dry lab" the test and sent out a generic answer to everyone.

And then there's this statement from TAMU admitting they had been relatively clueless on their approach to soil testing for phosphorus. I still don't like their approach to soil testing. Prior to this admission they had been telling everyone, and I mean everyone, to stop using phosphorus as a fertilizer because there was already too much available phosphorus in the soil. Shouldn't they have gotten a clue from the fact that everyone else in the world uses phosphorus fertilizer?

I prefer the testing methods from The Texas Plant and Soil Lab.

Dchall,

What are you growing that you need your soil tested?

Blutranes

Nothing. I don't test my soil. But I prefer the methods and materials used at the Texas Plant and Soil Lab over the methods and materials used elsewhere.

kimmsr: I'm with you. High-BRIX produce requires balanced soil. The key ratios for me are calcium/magnesium and phosphate/potash. I wouldn't know where the heck I am without a soil test every 4 years or so. I think this is very relevant for the all-you-need-is-compost lobby (and I am a keen composter -- "If you're not recycling you're throwing it all away"). I say this because compost contains lots of phoshate and potash which can shift that ratio considerably given years of enthusiastic application. Furthermore, I regard calcium as the key mineral and I don't think that one can maintain optimal calcium content in intensive cultivation without some soil ammendment; so how would one know how much to add without a test. Don't guess, test! Regards, Peter.

whats the most cost effective way/tool to do a soil test

Contact your local office of your state universities USDA Cooperative Extension Service about having that done and then dig in with these simple soil tests to see what you have.
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

It is with great trepidation that I enter this discussion but here are my thoughts on soil (and I must include growth media in my definition) tests.
In a commercial operation the practice is essential.
In a homeowner environment it is of limited value.
For the specialist, specific soil analyses add great interest and gratification to their particular pursuit.
As for tests themselves, it is more important to understand and interpret the results.
My first question usually is what was the extract used in the process. Water extracts will show different results from acetic acid extracts on the same samples.
Exchangeable pH is as important to me as pH.
Tissue analysis is the proof of the pudding and is more important in the short term for the commercial operation.
I was often bemused by the homeowner who would buy a 5# bag of aluminum sulfate to put on his 5000 sq.ft. lawn to increase the acidity on a "fine sand" of pH 7.8 all the time fussing over the computer print out obtained from a reputable University. I have great respect for the fine minds who collectively serve as the dynamo that powers the University system and I am not competent to comment upon their ranking or merits.

Like all other things your soil test is a guide, a resource. Since Joe Homeowner is one of the major contributors to the pollution of our world today knowing whether you need to spend you money on X brand of fertilizer or not is better for you and the rest of us than simply dumping some fertilizer yout soil may not need on your soil to flow out and into the water supply. A soil test will help you make that decision.