Software
Houzz Logo Print
engk916

newbie help with improving clay soil

18 years ago

hi, i need help improving the soil of my garden. we just installed a walkway that made room for a great spot, but it's covered with rocks. i noticed during the installation that there seems to be a really thin layer (the constractor said it was 3 inches, but it seems more like 1") of topsoil that lies over hard red clay. i mean, it's so hard that it almost seems like a sun-dried brick when left exposed.

i know it will take a few years to improve the soil, but i'm somewhat of a newbie, and am not sure how to go about this. my husband feels certain that the only way to grow anything in this rocky clay patch is to buy a lot of topsoil and manure to create a raised bed. is this the only way to do this? i know i need to remove the rocks, but beyond that i'm not sure how else to add biomass and break up the hard clay. if anyone could recommend a multi-year plan that would be great. i thought of planting something small like squash and tomatoes this year, then sowing a nitrogen-adding green manure like hairy vetch for the spring. or something to break up the clay pan like alfalfa. however, i'm not sure if that would be a mistake because i heard it could be hard to kill in time for the spring planting.

here's a picture of the garden area so you can see what i'm dealing with:

http://s283.photobucket.com/albums/kk282/engk916/?action=view&current=theyard.jpg

it isn't a large space (8' x 14'), but roomy enough to grow a few things for our family of four. if anyone could help this newbie with some tips i would really appreciate it.

thanks!

Comments (27)

  • 18 years ago

    Here is your picture.
    {{gwi:142983}}

    I can't give you a multi year program because it usually only takes a few months. Cover it with 3 inches of mulch, keep it moist, and in three months you'll be able to dig it with ease. Keeping it moist is usually pretty easy because the mulch will hold the moisture in. The fungi and bacteria that grow in moist soil under the mulch will provide the biomass you spoke of.

    What do you ultimately want to grow there?

  • 18 years ago

    Typical New Jersey soil, ecept that around Cape May. The best way to start a soil improvenment project is to contact your local office of the Rutgers University USDA Cooperative Extension Service about having a good, reliable soil test done for soil pH and base nutrient load. Also dig into that soil with these simple soil tests,
    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.
    which will give you a better idea what you need to do to make the soil you have into a good, healthy soil. All you need do is add organic matter to what you have, there is no need to buy "topsoil" to but there since any you do buy will be 95 percent of what you already have (the mineral part of soil) and only 5 percent (organic matter) what you need.

    Here is a link that might be useful: Rutgers CES

  • 18 years ago

    I would suggest 3 things to improve your soil;

    #1 Add some organic matter to improve structure. Compost leaf, mold, manure or whatever you can get your hands on.

    #2 Adjust the pH (if necessary Âget a soil test). Red clay sub soils are commonly very acid. If you are going do some amending with organic matter you can ad lime at the same time. There is no point in improving the structure if pH is 4.8 because nothing is going grow.

    #3 Be very careful about tillage. If the hard red clay is too dry you will not be able to get it stirred up because it will be nothing but massive hard clods. If it is too wet you will smear it and destroy any existing structure. You really do not want to smear it because it can take many years to get it back to where it was. If the moisture content is just perfect you will be able to till it up into little pieces and mix in amendments.

  • 18 years ago

    And don't get to worried about the red clay. If it's red, it means that there is oxygen present. I've learned to love my red clay....and so do all of my plants and lawn.

    We tilled the planting beds once to incorporate organic matter, but never after that. Mulch is replenished once or twice a year.

  • 18 years ago

    we don't have red clay here, but we do have blue/grey buckshot/gumbo. teh Extension service says for our cly the only thing to do is to till in sand at about 50% mix. so if you want 6" of good soil you put 3" of sand over it and till them together a bunch of times untilt eh top 6" is sandy loam.

    you can add organics for a quick fix, but you MUST add them back every year in our area. by using sand you usually don't have to keep converting the clay, maybe once every 10 years or so you do it again.

    RED clay in the hills close to me has a lot higher sand content than ours, so there your only choice IS to add organics every year.

    i agree with the others above, see what your composition is and find out from teh extension service what you need to do.

  • 18 years ago

    thank you, i looked up getting a soil test from rutgers and found out that i need to wait six weeks. the fool that i am, i double-dig the bed and added some composted manure this past weekend because i'm expecting some tomato transplants in the next week or so from burpee. so i guess i can't get my soil test for another six weeks, but it will be at the top of my to-do list. btw, the clay was so hard that i couldn't get my spade down more than maybe 6-8" (the length of the shovelhead). is this normal? because of how hard it was to dig the bed i'm wondering how anyone could add sand since it was so darn hard to dig up the first time.

    as for what i'd like to plant...from what i read, mostly "heavy feeding" veggies like broccoli, squash, brussels sprouts, tomatoes and some snap peas. down the road if the soil can improve to a reasonable depth, also carrots.

    i have another dumb question. how far away from the house should i locate the compost pile? i don't have one yet, and it seems foolish to pay for bags of it when i can make some myself. but seeing as i have never actually composted i'm wondering how to go about it. i can use everything except protien/fats, right? but what about grass clippings? i'm just worried about throwing in some clippings that might have some nasty pesticide thrown on it.

  • 18 years ago

    oh, btw i noticed while digging the soil that there was a strong smell of sewage - any idea what that could be?

    there were almost no earthworms....sigh!

  • 18 years ago

    A 'sewage' smell almost always means that the site is anaerobic....with a population of bacteria that don't need oxygen and give off sulfur dioxide.

  • 18 years ago

    I thouroughly agree with the suggestion to heavily mulch the area. also ading ag lime, river sand, and organic matter are very good ideas. The sand will improve your drainage, as red clay does not drain well. Ag lime will improve tilth, among other things, lime being an all around gardener's friend. Happy gardening!!

  • 18 years ago

    Adding sand to clay soils is not recommended by any of the soil scientists that I have talked with and every agricultural school that has something out about this will tell you that you need to add between 45 and 75 percent sand to make much difference. Far easier to add organic matter which because it is what the Soil Food Web lives on does need to be added every year.

  • 18 years ago

    yikes! i knew that sewage smell wasn't a good sign, but at least there's a way to fix it...

    thanks for the tips, i'll post back in a month or so when i get my soil test done. :)

  • 18 years ago

    kimmsr, that is why the experts here say you SHOULD add sand, you put in enough to change the soil composition. then you work in the organics as needed. if you try it around here with JUST organics, you will never get much more than an inch or two of decent soil.

  • 18 years ago

    The soil scientists at Rutgers, Cornell, UCONN, Michigan State, Purdue, OSU, Wisconsin, Washington, North Carolina State, and numerous others all state that unless you add between 45 and 75 percent sand to clay you will do nothing. I have seen nothing from Missouri since Dr. Albrechts papers that say anything about adding sand and he was one that stated adding sand to clay would do little unless very large quantities were added.

  • 18 years ago

    i am from Mississippi, not MO.

    but READ what i posted, mix in at 50%. that certainly falls inthe range you listed. and it is a very effective LONG TERM solution. mixing in a few organics does nothing to improve the soil below the first couple inches. you mix in the sand to change it to a more sandy loam, then add your organics for the nutrients. even when the nutrients are used up, you still have good soil that will easily take amendments.

    i dug up my septic lid yesterday to check the tank since it has been a few years since it was pumped. it took me 30 minutes to dig thru the clay. the hole was about a 20" circle going only 12" deep. the very top layer near the grass was decent loam, but below that i may as well have been digging in half dried pottery clay. i had worms galore inthe top 2-3 inches of soil, the last 9 was nothing.

    just about 100 feet away is my garden. this area had truckloads of sand added to it 30 years ago. even parts tha thave not been gardened in many years you can dig a hole 3X the size of the one i dug yesterday in only a few minutes. i do have a couple areas where the clay has started to revert, but i can deal with those.

  • 18 years ago

    I have no idea what the scientists say, I have not read any reports, but I do have red clay soil, & can tell you from experience adding sand is helpful. It improves drainage, which is necessary when you have clay. I also reccomend ading organic matter and ag lime, we all know what the organic matter does, but the lime... well, it is a blessing to my garden; we have had heavy rains the past few weeks, my garden is beautiful and healthy, my neighbors has washed out. I give the credt for this to sand and lime. Lime will also help neutralize the ph of your soil, and make digging/tilling/harvesting easier. Happy gardening!!

  • 18 years ago

    check out expanded shale, worked wonders on Tx black gumbo.

  • 18 years ago

    If your objective is to improve drainage, adding sand is not going to help. That is unless you add a whole lot of sand. But if you are going to go to all the trouble and expense of adding 50 to 70 percent sand (or whatever was recommended above) you would be much further ahead to just have your clay hauled off and replace it with a loam.

    It is kind of counter intuitive, but the objective is not to physically separate the clay with sand or straw or whatever to make drainage channels, it is to increase the clays bonding to itself. By strengthening this bond the clay structure changes from an impermeable mass to a bunch of small tightly bound particles. What binds the clay together is humus which comes from the addition of organic matter. If you add organic matter to your clay soil, over time it will feel less sticky, the structure will improve, and it will drain better.

    If you do not believe me do this test; go to your garden and screen out a handful soil particles that are an eighth of an inch or so in diameter. Do the same somewhere else in your yard that had the same soil originally, but has not been receiving the compost, manure, etc that the garden has. Dry the particles and put some of each in separate glasses and add water. I guarantee you the non-garden soil particles will Âmelt long before the garden particles. By just looking at that mass of guck in the bottom of the non-garden soil glass it will be obvious to you that it is not going to drain as well as the garden particles that have retained their structure and pore space.

    This is precisely why you hear so many recommendations to add organic matter to mellow clay soils. Adding sand will not help. Pore some sand in with the non-garden soil particles, add water and know what you are going to get? Guck with sand in it that is not going to drain any better.

  • 18 years ago

    You already dug up your rocky soil, wow, what dedication. Plant the plants you have, but make a raised bed around them. Tomatoes send out roots through almost anything. You can just make a heap if you don't want to build sides. Looks like at least you don't have a weed problem there! Pile up as much organic material as you can get free. Possibilities include other people's bagged grass clippings, yard waste, and leaves, animal manure of almost any type, old produce from stores or markets, used coffee grounds from coffee shops, wood chips from your municipality, whatever you can find.

    You can buy topsoil and compost, but seems pointless when you can makes lasagna beds free, and get better results. Also, start a compost pile ASAP. Can be anywhere. Cheap containment method would be 3 pallets nailed together like this :_: or a double bin :_:_: better still. Good luck!

    Marcia

  • 18 years ago

    Engk916, clay can be awful discouraging when you first start trying to improve it. It's so hard to work with; physically difficult to till, and seemingly-slow to change for the better.

    You've already had very good advice, above. As a general plan, this is the best suggestion I can offer from my experience: Keep the soil surface covered year-round with organic materials.

    Whether you cover the soil with mulch, compost, manure, wood chips, or green manure plants -- as long as you try to sustain a blanket of organic materials on top of the soil, it will continue to improve.

    The positive side of clay is, it tends to hold onto soil improvement. Though it may not seem there's much change from one year to the next, the longer you keep adding organic materials to it, the better it gets.

    One of the standard garden truisms is "The first year is the hardest." If you can try to think of your soil as a savings account, and keep adding steadily to it over time, within a few years you'll see a large change for the better.

    The FAQs on the Soil, Compost and Mulch forum offer many suggestions and good ideas about soil improvement. I'd strongly suggest reading and re-reading them.

    All the best,
    -Patrick

    Here is a link that might be useful: Soil FAQ Page

  • 18 years ago

    Adding organic matter to soil is supposed to be an every year thing, Ma Nature would not have developed so many plants that provided so much organic matter every year if this was not the plant, to add this material to the soil to support the growth in the coming year. Soil is composed of the mineral component, the clay, sand, or silt, and the living component, the organic matter. Most often the mineral component is around 95 percent and the Organic matter is around 5 percent, so adding more of the mineral component really does little to help make any soil into a good, healthy soil, but adding organic matter, which the Soil Food Web lives on, will help make that soil good and healthy so it can grow strong and healthy plants.
    The link below will take you to a treatise written by Dr. Elaine Ingham about your soil and what goes on in it, something everyone that wants to be an organic gardener needs to know.

    Here is a link that might be useful: The Soil Food Web Primer

  • 18 years ago

    kimmsr,

    So you do realize that the plants you are adding to your soil came from another soil somewhere right? What did Ma Nature have in mind for that soil?

  • 18 years ago

    I was in your shoes last year so I can only imagine what you're feeling now :). My whole backyard is full of rock hard Californian clay soil (also with lots of rocks I have to pick out, and concrete chunks, and roof tiles, you name it!). During spring and summer it's like one giant brick, it's impossible to dig and you can see huge deep cracks everywhere.

    So as someone who knows what you have to deal with, my recommendation is lots and lots of organic matter! As much as you can possibly get your hands on! And like others have mentioned never leave the soil bare, any mulch you have on top will help retain moisture and slowly improve the structure of your soil. Slowly but surely you'll build a population of earthworms which will help you out (I also had 0 last year). You'll have to keep adding stuff every year too. I thought I had added enough organic matter to certain locations in my backyard only to find it had disappeared this year! (The soil was still clay, but it was much easier to dig since I'd already done it last spring).

    I would suggest making paths in your garden so you don't step all over the soil you worked so hard to improve and compact it, as clay so easily does (the oxygen you introduced while digging is important for root development). I also recommend not working the soil when it's too wet (and sticks together) and if it's too dry letting the water soak in will make it much much much easier to dig. The upside is, clay usually has lots of nutrients and once structure is improved will be wonderful stuff!

    Raised beds weren't an option for me (I live at home and my mom didn't want any) but I've only heard wonderful things about them from other people with clay soils so you might want to go that route (a lot less/no digging for you). You won't be stepping all over the soil compacting it either.

    And the last thing that comes to my mind is try seeing if you have a local community compost place. I had NO idea I could pick up FREE compost at my local recycling center (I can get up to 1 truckload a week!) until this year. Sometimes it has little bits of plastic in it, or maybe a golfball or some other random object but it's helped my backyard out immensely now that I haul in as much compost as I can carry per week free :) Our community compost gets tested too, so I'm not worried about diseases or anything.

    Whew, that was a long post! I hope that helps! Happy gardening! :)

  • 18 years ago

    lemonwater, i think my situation is the most similar to yours in that there's a limit to how much i can spend to change the soil. i can't see myself trucking in loads of sand to change the composition (like fertilizersalesman said) because i might as well truck in the same amount of topsoil to make a raised bed. both would be prohibitively expensive. my community used to offer free compost, but it was closed last year because the town realized that the compost might be contaminated with heavy metals since the site was previously used as a dump.

    based on everyone's very helpful tips, i'll mulch well this season and hopefully i can convince some earthworms to take up residence! i was also thinking of planting a cover crop this fall. while i like the idea of letting plant roots break up the clayplan for me, i'm worried that i'll just be dealing with another problem of unwanted growth or hard-to-kill cover crops. i thought of using alfalfa or hairy vetch, but like i said in my original post, i'm a newbie and really don't know anything about this! has anyone tried going this route? i know i'm looking at a long road since i'm starting from scratch, but i'm quite patient because i know the results are worth it.

    thanks again,
    engk916

  • 18 years ago

    engk916,

    You could plant oats in the fall. They will grow some and eventually freeze out so you won't have to worry about them in the spring.

  • 18 years ago

    thank you, i'll sow the oats as soon as my tomatoes are finished (or die :) this year. i just finished planting yesterday before the rains came today. i will plan on adding some paths too, after all the hard work of digging up that horrible clay, the last thing i want to do is compact the soil by stepping on it! i bought some hay and mulched the heck out of my little rock patch.

    btw, what's lasagna gardening? i looked it up on google and saw it's a book. would there be a faq that provides the same info or would the book be a worthwhile purchase for a newbie like myself?

    here's an updated picture of my little garden:

    {{gwi:142984}}

  • 18 years ago

    People unfamiliar with the smell that comes from certain hardwood tree roots after they are broken might confuse it with a sewage smell. You can often smell the former when land is being cleared by bulldozer. One would have to have a mighty shallow water table to smell hydrogen sulfide from anaerobic soil with just a normal gardener's depth of digging. With a true sewage smell the first thing I'd look for was sewage, though spilled gas or fuel oil can become septic underground and give a similar smell.

  • 18 years ago

    BTW suggestion. If you do plan start a compost pile recommend you don't have it piled using the side of your house. Pile will attract termites, earwigs, rollie pollies, cockeroaches, earthworms, toads, etc. due to the nature of the material in the pile. Not at all bad, but you wouldn't want the termites to find the other source of food, say your house for instance. :-)

    I have clay soil in VA, lots of clay and yes like the others recommend add alot of compost. I also did lasagna gardening with layers of browns and greens layers, then added burlap to hold it down and to keep in moisture. Made three rows of them, probably scared my neighbors because it looked like shallow graves. LOL. Works great, you can find sources of info all over the Web via google.