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I'm trying to kill off a large area (30'X30'X4') of living grass that has been established for hundreds of years. What would be the best way to kill off this grass? I do have a 30'X30' grain plastic tarp that I'm putting logs and pallets around/on the tarp and was wondering if I can do anything else to compress the area quicker to kill the grass in the area so I can hopefully do about a 700' long area during the winter winter in order to have wood chip trucks fill the area with free wood chips to try to establish a large garden next year with. I do know that this area will sink down a lot as it shakes a little when dropping about a 100 lbs log on the ground in area.

black thumb
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    What you've done will work just fine. I would throw some pure nitrogen on top of the dying biomass to feed the decomposers to allow them to decompose faster. Next time, chop that biomass up first. What the heck do you mean that your ground shakes when dropping a large log or weight on the ground? This might be relevant to your subsoils...do you have limestone as bed rock in your area? You might have a large 'cavern' beneath the surface of your soil...especially if you live on a creek. – stormy Jul 30 '18 at 23:10
  • digging the horseradish bed today i only saw black dirt, ash, and tree roots. from the looks of it the soil is very well water logged. – black thumb Jul 31 '18 at 03:52
  • What does 'black soil' mean to you? Water logged means no air, saturated soils and few if any thrive in saturated soils. Do you use a specimen microscope? Gosh they are CHEAP as in $20 bucks maximum. Amazon...I love the microscopic world. Black dirt does not at all mean 'fertile', having chemistry plants need to do photosynthesis. Horse radish needs drainage. Most root crops need great drainage. – stormy Jul 31 '18 at 08:15
  • it was built up for a very LONG TIME!!!!!, and probably full of worm castings – black thumb Jul 31 '18 at 11:59
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    Worm castings are like 2-1-1. The nitrogen gets used up quickly when there are things like bark chips to decompose. It doesn't go to the plants first and little to nothing of the nitrogen will be left after decomposition. Wonderful for the soil organisms who then aerate and mix the organic matter into the soil without tilling. I always have great soil no matter what soil I have to work with. Worm castings are in the bale of decomposed organic matter (that, sorry, is not very well decomposed but close enough) I use first few years. Less later. Ash is not a good soil amendment. Makes goo. – stormy Aug 03 '18 at 23:45
  • @stormy I don't have worm castings, I have swamp/creek side castings that built up more over time, and we're trying to dramatically push back the grass by building a garden with grass on the bottom, then cardboard, and finally wood chips for anything breaking through the cardboard. – black thumb Aug 04 '18 at 04:37
  • Same thing, black thumb. I always loved using the sod I cut out of a lawn to make new plant beds or beef up old ones. All things once alive will die and decompose no matter what you do. Better to add a bit of nitrogen to hasten the decomposition process. That cardboard, what do you expect of that layer? Is that for weed control? The chips as well? Ummmm. See, I NEVER worry about weeds. I focus on growth and happiness of my cash crops. Weeds are so dang easy to control. No pesticides necessary. Only the top 2" of the soil has seeds that will germinate. – stormy Aug 05 '18 at 07:34

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In general, I've heard technique of tarping over grass (and weeds and...) and killing it with heat and UV is called Solarizing while tarping to starve weeds of light is Occultation. If you use a clear tarp it's solarizing while opaque tarps are used for occultation. Another common method of covering soil is the "lasagne" method or the back to eden method, both of which are basically similar.

  • Solarizing works by heating the ground using a clear plastic tarp for 4 to 6 weeks. It kills weed seeds in just the top few inches and also kills many small insects and fungi/bacteria. It also kills beneficial insects/fungi/bacteria, so you should balance that out after the solarizing process. If the soil is disturbed after solarizing, weed seeds from below the top few inches may be turned and may become viable. Here's an article on solarization
  • Occultation is done similarly to solarizing: laying down an opaque tarp over the ground. This doesn't get as hot and tends to cause plants to germinate. Once germinated, they either die (if left in the dark long enough) or are in a weak state of growth that makes it easy for the gardener to simple pull them to kill them. Soil that has been treated by occultation should, again, not be worked as that will bring up viable seeds. Here's a good article on occultation.
  • Lasagne gardening and Back To Eden gardening work as a form of bringing in a known-good soil on top of the old soil. This causes the same effect as the occultation process and the good soil on top should not have any weeds.

All of these processes should ideally result in the decomposition of that cut grass, but I'm not sure it is technically "composting."

I think the first step of all of these processes has to be to mat down or cut down the 4 foot tall grass. A string trimmer seems well suited to cutting it down, but it could take a while. If you "chop and drop" the grass then the cut stems can be combined with a carbon material to become the base layer in a lasagne garden. You could also try rolling over the surface with something like an ATV or tractor to simply flatten the grass stems before using one of the above techniques.

greggles
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  • Anything that was once alive and now dead is definitely in a process of decomposition. Any nitrogen available is being used to 'feed' the workers, the guys doing the decomposition. What is this CARBON layer? The finer organic material is chopped the faster the decomposers will be able to do their job. Why oh why do you guys think this makes fertilized soil. Please tell me. – stormy Jul 30 '18 at 23:35
  • A known 'good soil'? What exactly does this mean? There is no soil without weed seeds unless sterilized. Or if you use human poo plus sawdust completely decomposed. No weed seeds and no pesticide residues a bit of heavy metals and the most nitrogen available to plants of all the decomposed mulches. But not enough to not fertilize with balanced fertilizer. – stormy Jul 30 '18 at 23:38
  • @stormy thanks for your comments and feedback. I made a small edit to clarify one part that I think you might have been addressing. If you have the time to answer the question and perhaps clarify some things you think I got wrong I'd love to read your answer (and upvote it). – greggles Aug 03 '18 at 18:57
  • Your answer is good Greggles. I would use the solarization and clear tarp. The opaque tarp would take longer allowing seeds to germinate to then be starved. All soil, unless sterilized and even then only partly kills some seeds, will be full of seeds. The only medium I've found without weed seeds is human poo and sawdust anaerobically decomposed as well as aerobically. No weed seeds. No pesticide residues (this is becoming a big problem). Mulch 2" over any soil and you can forget worry with weeds. This is the stuff that feeds the soil as well as vastly reduces weeds. This is the stuff! – stormy Aug 04 '18 at 00:09
  • Lasagna was used for composting, not to make plant beds. Someone just thought that might work great. I do not. Artificially making layers in the soil disrupts drainage and soil life. All that newspaper, cardboard and wood chips have to decompose FIRST. Most certainly will also use up nitrogen the plants need. Hugelkulture, Back to Eden, Lasagna gardening all make NO SENSE at all. To me. I want to KNOW what the chemistry is in my soil without doing tests. I always use a balanced fertilizer NPK and watch my plants for micro chemistry issues for tiny tiny deficiencies or even excess. – stormy Aug 04 '18 at 00:17
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It sounds like you want to do the Back to Eden thing. I have no experience of this but

HOW TO GROW A BACK TO EDEN VEGETABLE GARDEN:

For an ideal Back to Eden garden, apply 3-4 sheets of newspaper. Then apply 3-4 inches of organic compost or composted manure. Then an additional 2-4 inches of wood chips or alternative covering on top. If you are implementing the methods in the Spring or Summer, additionally apply a dusting of composted manure for organic fertilizer.

WHEN TO COVER A BACK TO EDEN GARDEN:

For an ideal Back to Eden garden, cover your garden in the Fall! If you look at creation, nature drops its needles and leaves in the Fall. Note: *If you are using raw wood chips, allow time for them to break down (at least Fall - Winter). You will experience more work fertilizing with organic manure if you wait until the Spring or Summer to apply raw wood chips. Note: *If you are using composted wood chips that have had time to decay, you may apply and plant in the compost immediately. Note: *If you are using composted wood chips that have been screened, you may apply and plant in them immediately (Paul prefers this method for his home garden).

Composting is the decomposition using aerobic bacteriae usually of previously live biologic materials. So, you need to kill the grass first, and that's what the newspaper is for - to exclude light. You don't want to compress the area as that will cause soil compaction which doesn't help anything to grow. Plants need air spaces in the soil for their roots to breathe.

http://www.backtoedenfilm.com/organicgardening.html

Graham Chiu
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  • I've established a few small back to eden beds, but none with 4' tall grass. Will the heirght ant thickness of the grass be more difficult? – black thumb Jul 30 '18 at 14:42
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    You should add the fact the grass is 4 foot tall in your question. Sounds like a job for your chicken tractor. – Graham Chiu Jul 30 '18 at 20:24
  • That soil is compacted no matter what. If we haven't double dug that soil we are trying to plant seeds in compacted, too damp soils that we think are full of NUTRIENTS. What does BACK TO EDEN beds mean? What are the benefits, what is the purpose what are the negatives? There has to be negatives. @blackthumb my fav cover crop is annual rye. It is 3' when it needs to be chopped up and double dug into the soil in the spring. Add a bit of nitrogen to help the decomposers decompose the biomass. Weedwacker is best to use on cover crops before lighting turn the soil over with a spade. – stormy Jul 30 '18 at 23:16
  • 'lighting'? lightly...? – stormy Jul 30 '18 at 23:39
  • Cover the grass, grass dies, roots die, and the spaces occupied by the roots open up to become air spaces. – Graham Chiu Jul 31 '18 at 00:50
  • I suppose they become air spaces temporarily until the first major rain. What is wrong with double digging and making a fluffy bed that is a good foot off the normal level, adding trenches to WICK the water and improve already great drainage no matter what type of soil one has! That is air. I do this ONE time. I seriously couldn't imagine planting in undisturbed soil. I will NEVER plant in compacted virgin soils. Soils in place. Back to Eden just goes against the grain for me concerning gardens. Ugh, ADDING weird layers of paper and ash and compost make no sense what so ever. – stormy Aug 03 '18 at 23:57
  • I take it back; I will plant trees in undisturbed soils, otherwise I will always double dig a bed down at least a foot ONE time. There is usually 3 to 4 feet of soil after double digging (I am throwing shovelfuls of decomposed organic matter into the pile, willy nilly). After raking the soil down, flat on top, bed at least 3' wide, I take a piece of plywood and jump up and down on it. Then I dig a shallow trench around the perimeter between walkway and bed, throwing the soil on top of the bed. Then the plywood compacting to get the large air spaces out of the bed. This is done ONE time. – stormy Aug 04 '18 at 00:25
  • This newspaper and wood chips make no sense at all. Does absolutely nothing for the plant bed nor the plants...that I am able to understand. Just dumping decomposed organic matter on top of the bed, after plants are 6" or more feeds the soil organisms responsible for mixing this stuff into the soil, perfectly and within one season. Logs, and newspaper and wood chips and ash layers make absolutely no sense. And let's talk about WORK. Ugh? – stormy Aug 04 '18 at 00:28
  • @stormy you continue to rail against that which you don't understand! – Graham Chiu Aug 04 '18 at 01:34
  • Did I not ASK why everyone thinks these 'methods' are so groovy? I will continue rail until I do understand. If others have a problem explaining the benefits in a sensible manner that is their problem. Do you take on something just because everyone else thinks it is so greaT? I understand plenty with which to question the credibility and efficacy of these...methods. Huggs, Graham. Not ONE person has explained WHY they think these methods are better than good old fashioned plant beds. Not ONE person. I've been all over the gardening network and not ONE person can explain the WHY. – stormy Aug 04 '18 at 02:22
  • Because we don't ask and answer questions in comments. That's site policy. – Graham Chiu Aug 04 '18 at 02:46
  • @GrahamChiu That is just sad. This site is important not only for OPs but for us professionals. Trust me, I am a 'good girl' and always follow the law...to a point. Once a 'law' is causing loss of information exchange, honest information exchange that law should be challenged. Don't care how one decides to challenge bad rules but to go along to get along...can only go so far. – stormy Aug 05 '18 at 07:40
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The old way of doing this would be to cut and stack the sod/turf on one side, till over the ground, let weeds appear, handle the perennial weeds that appear and then till again.

A sod cutter may be available for rent in your location; how long that would take would depend on how quickly you learn mechanical things and how carefully you can follow instructions. Otherwise 30x30 is not such a large area and might be cut by hand with a spade, which requires a strong back and determination. But since you appear to be tossing heavy logs with ease this will not be a problem. Turves are stacked upside down and allowed to rot like a regular compost pile, eventually to be returned to the new garden as a top dressing.

Colin Beckingham
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  • sod cutters can cut through 4' tall grass? – black thumb Jul 30 '18 at 14:40
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    Hmm, I was wondering where the four feet came from. That would be a separate operation. – Colin Beckingham Jul 30 '18 at 14:46
  • Colin this would be my method...after weed wacking the biomass down to the ground. The sod cutter will cut out the weeds, biomass and weed seeds in the top 2 inches. I use that soil turned upside down for new plant beds and/or smothering live weeds. – stormy Jul 30 '18 at 23:06
  • And someone please tell me the thinking, the reasoning, the benefits of rotting logs below a plant bed? Why not just do a proper double dug bed? – stormy Aug 04 '18 at 00:00