Helping garden soil retain water

mcaren(8, Va. Beach, VA)April 21, 2009

I've followed this forum on and off for a few years, and have tried to put the advice given to work in creating an organic garden. About 3 years ago my family and I started a small raised garden bed -- we initially ordered a few truckloads of a topsoil/compost mix, and have added our own compost since. The initial soil looked great -- a nice dark brown -- but after working with it for the first year we realized that it only looked nice -- in fact it was basically dark sandy sterile soil.

We've added our own compost for two years and have grown two winters of cover crops that we dug into the soil each spring. We actually moved the garden this year to a new spot in our yard, and while digging up the soil to move it we FINALLY noticed earthworms (until this spring it was still relatively sterile soil). Not a lot, but a few here and there.

What I am noticing is how sandy the soil still is, and how it does not retain water. I would have thought by now that we'd have improved the soil quite a bit, but that would not appear to be the case. As a matter of fact, we've had rain for a few days and while our yard is a mucky mess the garden soil is dry and barely clumping.

Is there a point where you have to add clay or something like that? Can anyone offer suggestions as to what I can add to this soil to encourage some clumping and water retention?

Thanks. mcaren (in Va. Beach, VA -- near water, yard has acidic soil although garden is "fabricated" soil...)

Thank you for reporting this comment. Undo

I stole this...... Sounds like you're doing this, but article stresses you need a lot of organic matter. A cover crop won't give you enough........

Improving Sandy Soils

A very sandy soil will grow very little plant life unless organic matter of some type is added to it. The only way for a soil to acquire organic matter in proper proportion is for the garden enthusiast to incorporate it himself. Organic matter improves the texture of sandy soil by filling the spaces between the tiny stones (of which sand is actually composed). The filling of the spaces also increases the water-holding and nutrient-holding capacity of the soil, therefore, holding both water and fertilizer where it is available to plants.

Organic Matter
Organic matter consists of materials derived from plants and includes such materials as animal manures, peat moss, straw, leaves, compost, native peat, old sawdust, garden refuse and sod. Organic matter is a temporary product and must be maintained in the soil. For most gardens the incorportation of organic matter into the soil each year is a simple matter; but for lawns, organic matter can be incorporated only at the time of construction.

Rate of Application
Several months of preparation should go into supplying sandy soils with organic matter to properly improve the soil. Several applications of organic matter several weeks apart should be thoroughly incorporated into the soil and allowed to settle before planting. The organic materials should be applied at the rate of 6 to 7 cubic yards per 1000 sq. ft. of soil surface. This would amount to about a 2 inch layer of organic matter spread over the soil surface. This would be incorporated into the top 5 or 6 inches of soil. Lighter applications are of little value.

Incorporate thoroughly
The organic matter can be spaded, forked or plowed in, but should be thoroughly mixed with the existing soil. The most satisfactory method is roto-tilling. It is best to accomplish this incorporation several months prior to planting to allow time for the organic matter to break down and settle itself in the soil. If available, some topsoil mixed in along with the organic matter would further benefit sandy soils. When using native peats, have your soil checked for lime requirement because this material is usually quite acid.

    Bookmark   April 21, 2009 at 7:54PM
Thank you for reporting this comment. Undo
shebear(z8 NCentralTex)

I have to add at least 4" of compost to our raised beds each year because that's how much the beds drop. The organic matter in the compost is broken down more each year and you have to replace it and not just little piddly amounts either.

    Bookmark   April 22, 2009 at 12:48AM
Thank you for reporting this comment. Undo
coffeehaus(7a Central VA)

You are faced with several challenges as you garden in sand. Sand is coarse and allows rapid water infiltration but also drains at a commensurate rate. Sand, unlike clay or organic matter, does not adsorb water since it is not negatively charged. It will also not adsorb cations, those positively charged compounds needed in abundance by plants. As the responder above noted, massive amounts of organic matter are indicated.

You are also confronted by the fact that organic matter is rapidly degraded by soil microbes in the presence of moisture, heat and oxygen. Gardening in a well-aerated soil in Zone 8 with plenty of moisture means that you must add lots of organic material and do it often to be successful.

    Bookmark   April 22, 2009 at 7:15AM
Thank you for reporting this comment. Undo
gardenlen(s/e qld aust)

g'day mcaren,

all you can do is to continue to add organic matter, compost whatever and keep the gardens heavily mulched with green type hay's ie.,. spoilt lucern hay or pasture grass hay, over here we have sugar can mulch as well.

maybe add in some mushroom compost derived direct from the mushroom farm, i hear over there many farmers are glad to see people take it away as they have to pay to dump it, over here it started that way but the farmer soon learnt that us gardeners are prepared to pay for it, good drinking money hey? and of course once money is involved it gets dearer and dearer as the farmer is distanced from the cost saving benefit it gave him when it was given away.


Here is a link that might be useful: lens garden page

    Bookmark   April 22, 2009 at 2:24PM
Thank you for reporting this comment. Undo

I don't have any advice for you, but does anyone know whether it would be beneficial add some soil from the yard to the bed?

    Bookmark   April 22, 2009 at 4:05PM
Thank you for reporting this comment. Undo

What you sandy soil needs is lots of organic matter. If you have been adding some and not improvement has been noticed then you have not been adding enough. From experience I know that sand needs lots of OM to get to the optimal 6 to 8 percent in the soil that will retain soil moisture. Sand, without organic matter, will not retain moisture.
Adding "topsoil" is largely a waste of your money as well as time and energy since that "topsoil" will be most likely 95 percent of what you already have, the mineral portion of soil, and maybe with luck have about 5 percent organic matter which you do need. So if you add something with maybe 5 percent OM to the soil you already have and that does not have enough OM how much OM are you really adding to that soil?

    Bookmark   April 23, 2009 at 8:11AM
Thank you for reporting this comment. Undo
gardener_mary(6 MA)

Just an idea. What is your native soil like? I think you said acidic, but is it clay, loamy or also sandy. I think you also said poor draining so I would suspect some clay. Maybe it would help to use alot more of your native soil and less of the purchased sandy top soil. I think acidic soil is easier to correct than very sandy soil.

Good gardening, Mary

    Bookmark   April 23, 2009 at 2:27PM
Thank you for reporting this comment. Undo

Organic matter (OM), specifically humus increases the CEC of the sandy soil. Increased CEC increases the soil's capacity to buffer water and nutrients. There are three things in addition to adding compost to the soil that will improve your sandy soil.

1. Fertilize your vegetable garden. Otherwise the OM is mineralize to supply plant nutrients. Fertilize the green maunre crop to increase the OM dug in.

2. "Water" your compost with a clay slurry. The clay will increase the CEC of the resulting compost. The clay will also improve the composting process as well as increase the nutrient content of the final compost.

3. Add zeolite to the compost and/or to the soil. This is a high CEC material that does not deteriorate like OM.

    Bookmark   April 23, 2009 at 4:13PM
Sign Up to comment
More Discussions
Can I use Miracle Gro Garden Soil by itself ?
I just bought Miracle Gro Garden Soil with some bags...
how would one add / help mycorrhizae
On another thread (very long and informative - why...
Hate new GW
I hate the new Garden Web! I cannot figure it out!
Miracle-Gro Garden Soil
I was at Home Depot this morning getting a few things...
Unique Problem with smell
I have what I would consider a rather unique problem...
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™