it depends. first, do you have tree roots under your beds? if so, the soil can get depleted quickly. second, which soil it is? Sandy soils get depleted in one year, due to nutrients moving down past the root reach. Third, compost is notoriously N-deficient, so that needs to be added every year. I do this by burying scraps, with four beds with permanent clover cover, by adding some urea, or by mulching with leaves and letting the worms and bacteria create some nitrogenous compounds.

Saying compost is nitrogen deficient is not quite true. It is true you lose some of the nitrogen in the process but a lot of the nitrogen gets tied up in the active food web that compost becomes. It is slowly released over time which will benefit the plants long term.

As to your question there are a few things you can do to help your raised beds long term. If you live someplace that has cold winters you could plant a nitrogen fixing cover crop near the end of your growing season that you chop and drop right into the raised beds. As the plants you cut and dropped onto your beds composts over the winter it helps add important nutrients back into the soil. You could do the same with grass clippings but be careful as it can mat and you don't want grass seed in your raised beds. If your soil lacks organic matter you can add fall leaves. When all else fails you can always add in some compost. Just be careful because to much compost can cause a problem. Plants use some nutrients faster then other and phosphorus and potassium can build up over time.

It is deficient relative to the minerals, of course, not in an absolute sense. It is the only nutrient that volatilizes (well S does that too, but to a much lesser extent). If compost were well balanced, P and K would not accumulate.

Get a soil test from a reputable source. In most areas of the U.S., your Agricultural Agent can point you in the right direction. Where I live, it's $7, and well worth it.

When you 'get' soil from someplace (even someplace reputable) you can't be sure of its make up. The best soils are 'built'. It's quite possible that the soil you have was built well, and has a good foundation of minerals, but there are many variables... such as the pH for example, and the drainage of your beds.

A good soil test will help you determine, and adjust, the balance of nutrients and conditions. I don't suggest either home tests, nor most nursery (quick) tests. Send it to a lab and they will give you a full spectrum report.

Most labs will offer not just the readings, but suggested ways of bringing the soil into balance. For the ones that don't, you can get help interpreting the test easily enough.

As pointed out, sandy soils drain quickly - a good quality for certain crops, but requires frequent additions.

Clay soils have loads of various minerals (sometimes in very good balance, other times... not,) but they can be lacking in organic matter and the processes that make those minerals available to plants.

Soils that are built upon conditioners... peat, vermiculite, coir, etc... have little-to-no mineral reserves.

So, even good soils, built for differing purposes, can have good qualities and yet not be able to support long term plant health. If the soil seems to have good qualities, it may just need supplements to keep it performing well.

One last thought... do your beds have good drainage? 'Good' drainage is moderate. Soils that drain too quickly can be dry and leach out nutrients. Soils that drain too slow can be soggy, salty, and not allow for aeration. Raised beds usually drain well if they have no bottoms, but it can depend on the soil or surface they sit upon.

I second the soil test. Probably nothing wrong with supplementing with some high N fertilizer while you're getting that done, if the plants look pale. If the test shows other deficiencies you can change over, but if P and K are OK avoid 'balanced' fertilizers like 12-12-12 so as not to overdo. P and K don't leach out as fast and can accumulate as glib pointed out.

Can soils be depleted? Yes, in three ways.

1. If you grow vegetables and then harvest them from the garden you are permanently removing those nutrients from your garden ecology.
2. Nutrients can leach down into the soil beyond the reach of plant roots, as Glib said.
3. The crucial N-P-K and trace elements can combine into compounds plants can't use, or lost into the atmosphere.

For this reason, gardens must be replenished with the nutrients that have been lost. Picture the natural forest floor. Leaves, twigs, and branches are constantly raining down and decomposing, eventually delivering fresh nutrients.

There are various ways to do this. Permaculture takes the long view, building a plant ecosystem that naturally recycles itself into a self-sustaining ecosystem with no need for outside supplements. Modern agriculture takes the short term approach of directly adding manufactured nutrients required by the plants, ecosystem be damned. And there is a wide spectrum in between using a combination of natural amendments that feed the soil biology and then let the ecosystem take it's course.

The starting place for best results and increasing your understanding of the soil is RGreen's advice for getting a soil test. That will involve the test, then interpreting the results and coming up with a prescription of amendments to bring the soil in balance.

If you are a more casual gardener and don't want to deal with testing and the subsequent learning curve, my advice for your next best option is to add compost (which you have already done - good decision on your part!), and a complete organic fertilizer (COF). These are mixtures of common organic amendments (soybean meal, feather meal, fish meal, kelp meal, rock phosphate, gypsum) designed to replace the nutrients and minerals commonly lost year by year.

Finally, I'll throw my opinion in to the ring regarding compost and nitrogen discussion. Compost is wonderful and crucial, but it is not a fertilizer (i.e. a source for N-P-K). Yes, there are some nutrients, but it is highly dependent on the source materials (were they nutrient-dense to begin with?) and the composting process used. Generally the faster (or "hotter") the process, the more nutrients (especially N) are used up (or more specifically lost into the air as ammonium ). Use compost in your garden for the organic matter, improved tilth, cation exchange capability, and benefits for the soil ecosystem as a whole. But for nutrients, look elsewhere.

I have had my best luck with focusing a little more on micro nutrients. My little garden has been in the same place for about 20 years now, and sometimes it shows. I think its real important to feed the bacteria and even the biological denizens. Sometimes people talk about how a bacteria makes a symbiotic relationship with the roots of a plant, but I think its even deeper than that, in that the connectivity also extends to nematodes and all manner of additional critters, and together they make the plants happy. My feedings and fertilizing seems to be most effective when I use a very broad spectrum of fertilizer and vitae at a lower rate but a little more frequently. But then, maybe its just the attention that the plants like. I dont do a lot of testing, its pretty obvious when the plants are not happy as we usually grow the same things every year.

Like I posted earlier it is going to depend on what you want to do as a gardener. You are going to lose most of the nitrogen in your garden as water permeates down through your soil. There are several ways to combat this. One is to keep adding nitrogen through fertilizer either store bought or home made. The other is to use nitrogen fixing crops like comfrey which draws essential nutrients from deep areas where most garden plants can't get them. You harvest the comfrey several times a year. The leaves break down extremely fast and when the leaves are dug into the soil there is little nitrogen loss.

How quickly any soil might become nutrient depleted depends on the make up of that soil, the amount of organic mater in that soil, and how active the Soil Food Web is, or was.

As some pointed out sandy soils tend to loose nutrients fairly quickly, because sand is not able to hold onto them and they flow out of that soil with the water. Clay soils, on the other hand tend to lock up nutrients so they are not available tot what ever may be growing in that clay soil. In both types of soil as the amount of organic matter is digested by the Soil Food Web the amount of nutrients available to plants will decrease, and that is the reason organic material in soils needs to be replenished annually, to keep the level up and provide the necessary nutrients to grow plants. This is one of the reasons why soil testing is important since there is not other way a gardener can tell what nutrients are in the soil and if they are fairly readily available to the plants (the soil pH).

In addition to a good reliable soil test for soil pH and major nutrients these simple soil tests may be of some help determining what might be needed to make a good healthy soil.

1) Soil test for organic
material. 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 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 your soil will smell, to a point. Too much organic matter
can be bad as well.

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.

kimmq is kimmsr

Did you work your compost into soil at all or just layer it on top? Was the layer thick enough to that you just planted in the compost or did you plant into the soil below? In the future I would work that compost into the top few inches of soil.

What are your plants problems? What other amendments or fertilizers do you use?

I like several others would recommend getting a soil test. I think taking some samples from your original soil and from a few different locations in your garden will tell you quite a bit. When taking your samples I would brush away your compost and get a 6" deep sample. Logan Labs seems to be strongly recommended here and on other forums. I used them this year and was pleased.

Thank you all for the information and answers - we will get a soil test done this season and go from there. As an update, my plants are looking a lot better in the garden beds, and I think my compost addition early this year has made a significant difference. I always grow my plants from seed, and this year the soil I used to start the seeds was unfortunately really low quality. Once the seedlings got settled in the beds, they took a while to get going. But the plants actually look pretty vigorous now.

Vegetables tend to be gross feeders. There are some exceptions (carrots for instance) but mostly, they need a lot of feeding.

The first year they did very well and are an indication that the compost you bought was good quality.

It seems to me that you are doing the right thing already: choosing good compost initially, making raised beds and making your own compost.

And all of that gives you time to learn about reconstituting soil. First year is the best. wonder why the 3rd is not?