How to amend garden soil that's mostly clay?

[QChickieMama]

I've used a garden plot here for 3 seasons, and after many disappointing yields, I'm realizing the soil is to blame. It's clay. When it rains, the garden becomes a pool and the plants rot. I've put a bunch of compost and composted horse manure in it over the last 3 years, but it seems it all goes away and only clay and rocks are left behind.

What to do to fix the soil? What should I add? I can till the garden with our tractor, but it doesn't go too deep. Should I just pile good dirt on top of the clay?

Thanks.

 

[1muttsfan]

I also have heavy cold clay, with the addition of heaps of jagged rocks. The only way a garden will grow here is by raising it. Use rocks, logs, pavers, or treated lumber for edging to raise your bed, 10-12" will make a world of difference. I started by digging out around 6-10" of the clay, edging the garden, then filling in with topsoil mixed with generous amounts of rotted horse manure, compost, old potting soil, and anything else that is rich and well-draining. You will see a huge improvement in your plants.

 

[1muttsfan]

This is one of my vegetable gardens, you can see the pile of manure just dumped in on the right waiting to get tilled in, as well as a few eggplants that were looking for a bathing spot.

 

[1muttsfan]

Here is another option for you - i am eyeing this for some border gardens around the edge of the yard

http://www.richsoil.com/hugelkultur/

 

[Life is Good!]

Sounds like our soil here!

We raised our beds 10" high, filled with potting soil, compost, chicken bedding, well rotted manure from our neighbor's horses and more compost. The thing that has helped the most is to top the gardens with mulch. Add worms if you have to (if using your own compost, you won't need to add worms, they're in there). The worms LOVE the mulch and reproduce like crazy, which means more dirt for your garden!

It's taken nearly a dozen years now, but we've got REAL dirt - anywhere mulch has been. I cannot tell you how much mulch I've spread on this property over those years - how many hundreds of bags we've purchased and pushed around with a rake....ugh.....but it's worth the end result. Good dark dirt. Neighbor's don't have dirt, they still have clay. We've got dirt because of those lovely worms!

Good luck, it's not easy, but well worth the efforts. But I know the raised beds helped get better harvests.

 

[lazy gardener]

If you buy purchased mulch, it's much more affordable to buy it by the cubic yard from a landscaping company. Many companies will deliver. More economical options include shredded landscape trimmings (like from road maintenance crews), mulch hay, litter from stables, shredded leaves, grass clippings. I agree, over time adding deep mulch will eventually improve any soil. To OP, I might add that you might need to improve the drainage of your garden site, then build the soil from there. Does water drain into the garden site? Does the garden site get full sun? Repeated tilling will slap that clay into an inpenetrable hard pan, so moisture can't drain below the depth of the tiller tines. How big is your garden site? How often do you till it? Can you take part of the garden, or all of it out of production for a season to try to fix the problem. You might try planting some heavy duty green manure crops to break up that hard pan. Contact your local county extension service for a list of green manure crops that would work well with your soil. You might also need to do some land work to route water away from the garden, and install some drain tile around the perimeter. All expensive fixes, but in the long run worth it if the garden site is otherwise ideal. It depends on how much you want to invest in the project and what your gardening goals are. Lastly, is your garden in the BEST location for you to grow a garden? I wish you the best of luck. I had a garden that was a far cry from ideal, with too much shade and root penetration from near by trees, heavy clay soil, and it took way too long to dry out enough to work the soil in the spring. I worked the soil for about 20 years, and it did improve, but not to my expectation. I finally moved the garden, it now gets full sun, has a gentle south slope, the soil is sandy loam, I can get in to it at least a month before any of my neighbors can touch their gardens, and it produces much better than the old garden did, even though it is smaller.

 

[TXchickmum]

We have clay soil, also. -have raised beds for our vegetable gardens. -also, raised the beds just a bit for our flower gardens and fruit vines. (We planted our blueberries in whiskey barrels since they need very acidic soil. -planted them in pure peat moss.) Our gardens have thrived!

A nearby city has a wonderful program for purchasing soil (called dyno dirt) and mulch.

http://www.cityofdenton.com/departments-services/departments-q-z/water-utilities/dyno-dirt

We purchase by the truckload and till it into our soil. -add tons to the raised beds. It is very, very economical! There may be similar options from municipalities near your area.

 

[QChickieMama]

If you buy purchased mulch, it's much more affordable to buy it by the cubic yard from a landscaping company. Many companies will deliver. More economical options include shredded landscape trimmings (like from road maintenance crews), mulch hay, litter from stables, shredded leaves, grass clippings. I agree, over time adding deep mulch will eventually improve any soil. To OP, I might add that you might need to improve the drainage of your garden site, then build the soil from there. Does water drain into the garden site? Does the garden site get full sun? Repeated tilling will slap that clay into an inpenetrable hard pan, so moisture can't drain below the depth of the tiller tines. How big is your garden site? How often do you till it? Can you take part of the garden, or all of it out of production for a season to try to fix the problem. You might try planting some heavy duty green manure crops to break up that hard pan. Contact your local county extension service for a list of green manure crops that would work well with your soil. You might also need to do some land work to route water away from the garden, and install some drain tile around the perimeter. All expensive fixes, but in the long run worth it if the garden site is otherwise ideal. It depends on how much you want to invest in the project and what your gardening goals are. Lastly, is your garden in the BEST location for you to grow a garden? I wish you the best of luck. I had a garden that was a far cry from ideal, with too much shade and root penetration from near by trees, heavy clay soil, and it took way too long to dry out enough to work the soil in the spring. I worked the soil for about 20 years, and it did improve, but not to my expectation. I finally moved the garden, it now gets full sun, has a gentle south slope, the soil is sandy loam, I can get in to it at least a month before any of my neighbors can touch their gardens, and it produces much better than the old garden did, even though it is smaller.

Our garden spot gets full sun, has no roots from nearby trees, and it's fairly level. It doesn't gather water from the pastures, but any water that falls into the garden stays. When we till it with the tractor, since the tines spin in one direction, the backside of the garden gets built up higher than the front part where the tractor exits. This is part of the drainage problem b/c the ground naturally slants toward the back of the garden.

I think what you're saying about repeated tilling that creates a hard pan has happened--but why is this?

The garden is about 20'x40'. We usually till it twice/year, in the early spring and late fall. We usually dump in our household compost at those tilling times.

I can look into green manure crops. Right now, the front half is planted in winter crops but the lettuce is only 2" tall after being planted in November. Hardly growing at all!

My current thought is to put a layer of sand, black dirt, and then composted horse manure on the back half of the plot for the spring planting. No tilling. Think that'll work? My crops from last season grew super well through 4-6" of soil before sending roots horizontally. Only okra thrived.

Thanks for your help!

 

[lazy gardener]

Sounds to me like you have a definite hard pan problem. Obviously, you are in a different climate than I am. I checked my favorite seed catalog and found the following 2 green manure crops that should be advantageous to you. Again, I recommend that you contact your county extension office for a list of green manure crops that would be helpful in dealing with hard pan in your climate and soil conditions. Bell bean is a nitrogen fixer which can be planted in early spring. Fixes up to 100#/acre in 6 weeks of growth, aggressive tap root breaks up hardpan and mines subsoil nutrients for secceeding crops. Forage radish (daikon): Fall and winter cover crop with a thick upper root 12-20" long and a thinner taproot up to 6' long. breaks up compacted soils and hard pan. Plant in stands of 5 - 8 plants/s.f. A good warm weather crop is buckwheat, though I don't know how well it would do breaking up your hard pan. I've never grown the first 2 crops mentioned, have grown buck wheat. If I were dealing with your problem, I'd take the whole garden out of production for a season of intensive cover cropping and mulching. I would start with Bell bean, work that into the soil (till minimally, don't try to get a smooth seed bed) follow it with repeated crops of buckwheat until onset of cold weather, then plant forage radish mixed with more bell bean, and field peas.

When you do till the garden, can you approach it from a different direction? Preferably tilling north to south if you have been tilling east to west. IMO, especially in clay soils, tilling does more harm than good to soil structure. clay soil is particularly vulnerable due to it's structure. Imagine a deck of cards: Those are clay soil particles. Imagine a bowl of marbles: Those are sandy soil particles. Imagine a bowl of little sponges: those are humus or compost particles. When you have clay, and work the soil, it lines those particles up so there is no space between them. That's what a potter does when he works a lump of clay to make a clay pot. The ideal soil structure is make up of the perfect blend of the 3 kinds of soil particles. I am a strong advocate of working the soil as little as possible, mulching heavily which will encourage build up of humus, and feeding the micro and macro soil life which will in turn nurture your plants and return the soil to good crumb structure. Now, will someone please loan my a ladder so I can climb down off my very high soap box???

It sounds like you have more land available to do a small garden adjacent to your current garden? If so, you could do a no till garden (research lasagna gardens), start gathering your material as soon as possible. When the frost is out of the ground, layer your materials, starting with newspaper or cardboard, aiming for a bed that is 2' high. I did a modified lasagna garden squash hill this last year, and raised 185# of squash in a hill that was about 3 x 4'.

 

[1muttsfan]

Tilling clay compresses it and eliminates the air pockets, making it even heavier and poorer growing medium. Tilling in humus helps some, but you still have the issue with compression and decrease in oxygen capacity. To really improve your soil you must add good quality dirt as well as humus, since humus breaks down and pretty much disappears. You could certainly try adding it to your poorly draining area, but it is likely that you will not get the same results as building elevated beds. and may find it will take several years to achieve significant improvement. You might try experimenting with one or two smaller raised beds this summer, they can be very intensively planted compared to regular gardens, and if built right are quite easy to take care of.