I'd guess it's based on what the last results were. If you had a test that said, "all's well", I'd assume what you're doing is right. On the other hand, I started a new garden when we moved in ~3 years ago. I had the plot tested, and it was basically "dead"--needed lots more NPK & Organic matter. I had it tested this fall and my P&K levels are high. I over-did it a little on the manure, I think. So I'll keep adding leaf-mold compost & have it tested again in 2-3 years, I think.

If you're an experienced gardener & are good at "reading" your plants, 5 year intervals in an established garden doesn't seem unreasonable to me.

OTOH, my dad has never had a soil test, and his tomatoes turn out just as yummy as mine. But he does have 30 years more experience on his side. ;-)

It depends. Many of the factory growers test annually while many home growers never have and never will. A soil test is one tool in a growers belt. If your initial soil test is way out of wack you might want to test annually to chart how what you are doing is working. But if you tests tell you that your soil is close to pretty darn good you probably have no need to test more often than once every 5 years.
"scientia potentia est", Knowledge is Power.

I test the pH of the soil around the base of our blueberry shrubs once a year, and add agricultural sulfur as necessary. Our native soil is high in clay, with alkaline pH around 7.6, so it takes some effort to keep the blueberries happy. However, I do not test for N, P, K, or anything else. The shrubs get small amounts of liquid fertilizer in the spring, and they also get compost and shredded leaves, as mulch. They are generally healthy and productive. Sometimes they are damaged in the winter months by browsing rabbits, but they grow back quickly during the spring and summer.

+1 on what JonCraig and kimmsr are saying. Depends on your situation, a little knowledge goes a long way, but no need to overdo.

Here's my latest soil test.........

What might be causing the high levels of phosphorus and potassium ?

Your Results pH: 7.3 Phosphate: 370 Potassium 640
Phosphate
0-25 (Low) 25-100 (Medium) >100 (High)
Potassium
0-125 (Low) 125-250 (Medium) 250+ (High)
Recommendations:
pH: The pH is high for some vegetables. Mix 1 pound of sulfur per 100 square feet into the soil during
the fall or before planting in the spring to lower the pH. Pelletized sulfur is easier to work with than the
dust.
Fertilizer: The levels of phosphorus and potassium in your soil are high. Use one of the following
fertilizers at the recommended rate.
Iron + (11-0-0) at 4/5 pound per 100 square feet
Nitrate of Soda (16-0-0) at 3/4 pound per 100 square feet
Ammonium sulfate (21-0-0) at ý pound per 100 square feet
Urea (46-0-0) at 1/4 pound per 100 square feet.
The fertilizer should be worked into the soil before planting.

P and K may be high because you've added lots of chicken manure.

What is the level of organic matter in that soil?
Too much manure as well as too much OM may be the reason for the high P and K levels.

Hmmmm......... Just as I suspected! Soooo, it's too much of a good thing?

kimmsr- How is the level of OM determined? The compost consists of 75% pine shavings/25% chicken manure (I have 7-8 hens)

Will adding the recommended fertilizer lower the P & K?

Will adding the recommended sulfur lower the pH?

Should I refrain from adding more OM (of this type)?

Is a 7.3 pH impacting certain vegetable production? I've read numbers as low as 6-6.5 and as high as 8 or 9 for melons, whereas onions are around 5.5 - 6.5.... I don't have great success growing either of these.

The culprits!!

{{gwi:108390}}

Here's another pic of compost pile...........

Organic matter is normally tested along with the other test parameters at the lab. However if you're adding compost it's probably not deficient.

Definitely cut back on the chicken manure compost. Use your 'other' compost for annual additions for awhile. High nutrients can goof up absorption of other nutrients. What they've recommended is using N-only fertilizers with no P and K. You have the same situation I have in my veg garden - too much P and K.

The sulfur should lower the pH so definitely add that.

Thanks toxcrusadr for your insightful input! I plan to add the sulfur & Urea in the spring..........

Don't know why my test didn't include a test for OM....... It was performed by my local extension.......

agree. I would go with only urea. I, too, have pH=7.7, and too high Ca, Mg, K, and P, and no chicken manure for ten years. If you want to be fine, sure, use ammonium sulfate. and there is no need to test for ten years either.

I'm one of them old timers that has never had a soil test. As far as I know my Father never had one either. His was a garden based on heavy grey clay, probably alkaline. Mine is a sandy loam, probably slightly acidic. Both were started and maintained the same over the years. Lots of various manures added and compost either worked in or used as a mulch. It's my understanding finished compost is slightly acidic and that is what most garden veggies prefer.
Funny thing is, I took a Master Gardener course several years ago and they stressed the importance of the soil test and I thought I would someday out of curiosity but never have. I'd probably try to change what I have and screw it up.

A soil test for soil pH and major nutrient levels is one tool a gardener can use to help get the soil into a good healthy condition.
cugal, adding the recommended fertilizer will not lower the levels of P and K, or even balance them.
Optimal pH levels for most plants is in the 6.2 to 6.8 range, but 7.3 is not all that high. Of more importance is the balance between Calcium and Magnesium.
Given the relatively small quantities of fertilizers recommended I'd not bother with them.
Determining the level of organic matter in soil is fairly simple an these simple soil tests can help with that.

1. Soil test for organic matter. 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. For example, 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 drainsâ 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 your 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.

Soil tests are not all the same, so it's possible your lab does not include OM in the standard test regime and you have to ask for it. Mine does N separately and charges a separate fee for it, for example.

BTW, your chicken manure compost pile looks like sawdust. I assume you're using wood pellets of some kind for bedding? I don't know how long you are composting that stuff, and maybe this pile is fresh, but just keep in mind that although poultry manure is very high in N, wood is very very low in N and takes a looong time to compost completely. If you were to add woody material that's not well decomposed to the soil, it could deplete N for awhile, resulting in stunted growth.

Thanks kimmsr for these guidelines! I only see #5 as being an issue in my soil....... I don't see a great number of earthworms, but I think I know the reason for this....... Sevin.......... I know spraying Sevin helps control garden pests, but also kills the beneficial organisms as well..........

That pile is just wood dust or shavings that chickens have run on for a little while, huh?

I strongly second the rec to not add too much of that at a time to a bed, or else let it sit a couple of years.

Well shoot......... It's very possible that my soil is lacking N..... As I posted earlier, the compost pile is probably 75% pine shavings & 25% chicken manure and yes it gets added when it's around a year old........ The pile in pic is fresh..........

I assumed the manure was supplying ample N.........

A year might be fine, it all depends on what the compost looks like. If you don't see pieces of wood, if it looks completely decomposed to humus, it should be OK. I've composted a lot of planer shavings and sawdust by mixing with grass clippings, leaves etc. and it seems to work in that amount of time. You may not have a problem at all, I just thought you should know to watch out for it.

Was the test for soluble NPK or for total NPK? Sometimes the P and K can be tied up in insoluble forms.

P & K high:

Most established gardens tend to accumulate "P" and some "K". The reason is that most gardeners keep adding, 10-10-10 or 16-16-16 . What happens is that N is either used or leached but most of the P sticks around and to some extent does K. Bad news is that you cannot remove them But good news is that they do not do harm.

Here is a double edged sword that you can use: ADD AMMONIUM SULFATE. It dos two things (1) supply N and (2) reduces pH. Epsom salt (Magnesium sulfate) also can help.

Just my 2 cents worth or less.

Kugal

1200 sq. ft is about a 30' x 40' garden and if that's your chicken maure pile just spread it on till it under and let mother nature do its thing. Over that area and the size of that pile your not adding that much.

JMO

have a great day

I might agree if it were only that pile, but we don't know how much chicken manure is in there compared to wood shavings, and how often a pile like that is generated. The pile looks very woody and not very manure-y to me.

+1 on the comments above about accumulating P and K. I was using 12-12-12 for a number of years because when I bought my house, essentially a new house on a former wheat field dug down into subsoil clay for home building, the soil was P deficient. Fruit trees I planted did not even bloom. I just needed to cut back, especially on the veg gardens, probably sooner than I did.

I appreciate everyone's input! Great bunch of knowledgeable folks here on GW!

c6-zr1 ( Hmmm, as in Corvette?) gives me hope! I've been doing basically what he's describing for several years. Although I have some very mellow soil, I think it needs more N.......

In sandy soils for those who don't use synthetic fertilizer you can be sure K is never high! I wish I could find a way to keep the K-levels up....

MOFGA put out a good little summary of sources of natural nutrients, liked below. I had to stop using Sulpomag because of high magnesium levels developing in my soils.

Here is a link that might be useful: Sources of nutrients

Bananas are high in K, but I have no idea what's in the peels.

Well now, a little Googling shows banana peels have about 80 mg/g K (or 0.08%) (dry wt basis I assume). I don't know how high that is compared to other fruit/veg waste, but it does have some. Another source said the peel contains about 40% of the K in the entire banana.

So if you have low K, find yourself a juice bar and get their waste. :-]

Alfalfa meal would be a better choice.

Thanks for the link marshallz10 ! Lots of good info there.... Chicken manure supplies three times the amount of N as does cow manure........ Didn't realize there was that much difference......