Plastic sheeting for weed suppression

Discussion in 'Planting, growing, nurturing Plants' started by Mirrabooka, Oct 18, 2018.

  1. Mirrabooka

    Mirrabooka Junior Member

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    several respectable Permaculturists are advocating weed suppression with UV stabilised black plastic.

    I wonder if members have any thoughts about this option? Suppliers?

    Thanks
    Peter
     
  2. Jason_H

    Jason_H Member

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    I have heard of clear plastic being the way to go. Warms up the soil holds moisture to promote germination, then the weeds germinate and get cooked under a hot sun. I think JM Fortier does it at his market garden in Quebec to reduce weed load when planting out.

    Black plastic should work too just by light exclusion. They use it a lot around here to keep weeds down in between strawberry rows.
     
  3. 9anda1f

    9anda1f Administrator Staff Member

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    Plastic mulch is used frequently by farmers around here (semi-arid) to suppress weeds and minimize evaporation.
    Personally I prefer to sheet mulch a weedy area using old cardboard, manure, and compost covered with straw. Once the sheet mulching has composted, weeds are easy to "yank-and-drop" as further contributions to soil building.

    One of many sources for plastic mulch: https://www.growerssolution.com/PROD/black-plastic-mulch-1-mil-embossed/SRMBlack
     
  4. mischief

    mischief Senior Member

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    I am going to try this method this year.
    The reason for this is because my new neighbour misunderstood me and instead of getting his contractor to clear the weeds off and THEN dump his beautiful virgin soil over the hedge onto my place....he/they dumped two or three loads full of weeds.
    A year later, it is a mess.
    I had to buy a base and mattress for somebody else, which came with all that "I can re-use plastic sheet".
    Woop Woop,Woop!!!
    What I am hoping to achieve with using this ,is kill the weeds by letting them grow under a 'mulch' of the clear plastic.
    Hopefully what should happen, is that the weeds will grow but cant really survive under a clear plastic sheet.....cook and die
    Or so I hope.
     
  5. Treemo

    Treemo New Member

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    [​IMG]

    [​IMG]
     
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  6. songbird

    songbird Senior Member

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    even UV stablised plastic is still eventually going to start breaking down and then you have to dispose of it.

    i much prefer cardboard with mulch on top of it (to hold it down or even use rocks if
    you don't have mulch).
     
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  7. Bryant RedHawk

    Bryant RedHawk Junior Member

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    The following information might be of interest to those in this thread, it is about a study done in Loess and potato farming methods there.

    Even though it is such an important crop there, potato yields are lower than they could be.
    The area has a dry climate with uneven precipitation.
    Droughts are common, especially in the spring when crops are just starting to emerge.
    If soil moisture was more reliable, the potato crops would do better.

    Rong Li and colleagues at Ningxia University in Yinchuan, China set out to discover if different tilling and mulching practices could improve soil moisture -- and crop yields -- in the Loess Plateau.
    The researchers studied three tillage options (conventional, no-till, and subsoiling) combined with three mulching options (no mulch, straw mulch, and plastic film).

    Usually, the Loess Plateau fields are plowed, or tilled, after the harvest and left bare until spring planting.
    This is known as conventional tillage.
    Conservation tillage can mean not tilling the soil at all between crops (no-till).
    Another conservation option is subsoiling: deeply breaking the soil with a long blade, without turning it.
    Tillage helps water soak into the soil and improve water storage within the soil.

    Li said, "We didn't know whether tillage with varied mulching practices would improve drought resistance during the potato seedling stage in these dryland farming areas."

    The team studied the same field over two years -- a relatively dry year followed by a wet year.
    For each combination of soil management options, they measured topsoil temperature, soil water content, seedling emergence rate, and marketable yield of potato tubers.

    Plastic mulch warmed the soil more than the other mulching options.
    Straw mulch had a cooling effect compared with no mulch.
    However, all three options produced soil temperatures in the right range for rapid potato germination.
    So it seemed that topsoil temperature was not the key factor for early seedling growth.

    The team concluded that drought was the main factor limiting crop production.
    Soil moisture during the seedling period is essential for crop success.
    Techniques that maintained soil moisture improved both the emergence rate and strong seedling establishment.
    Both are essential for good tuber formation and marketable yield.

    Other findings include:
    •Seedling emergence was lowest with conventional tillage and no mulch compared to other treatments.

    •The highest emergence rates occurred when subsoiling was combined with plastic mulch.


    •Within the same tillage option, seedlings in mulched plots were much taller than those without mulching.

    •Straw mulched plots had the highest potato tuber yield, followed by plastic mulch.


    •Conservation tillage (both no-till and subsoiling) with straw mulch led to higher potato yields and marketable tuber rates compared to other treatments.
    •The highest marketable potato tuber yield was found in the combination of subsoiling with straw mulch. This yield was 14.9% higher compared to conventional tillage with no mulch.

    Li and his team concluded that if the main goal is to increase soil moisture, straw mulch should be selected.
    Straw is also relatively low-cost and environmentally friendly, while plastic mulch can cause pollution problems and is a less sustainable method.

    "We recommend conservation tillage combined with straw mulch as a more favorable farming practice for drought resistance in potato seedlings," Li said. "This combination has great potential for greater crop production in our region and similar semi-arid dryland farming regions of the world."

    In the Loess Plateau, where the potato is king, these findings may prove to be truly royal.

    This work was supported by the National Natural Science Foundation of China.

    Notice that while plastic used as a mulch did work, they found that using straw as the mulch produced a better crop.
    So if you want to lay down a plastic mulch and then pick it up before it deteriorates into microparticles of plastic, go for it, but be aware of the short comings of using plastics, even those that are UV stabilized, they will begin to break down in a single year of constant use. That means if you don't get the plastic up and stored, you will run the risk of having some microparticle sized plastic in your soil and that stuff can last a hundred years in that state.
     
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