Does cardboard leech nitrogen from the soil? I'm thinking of laying a couple layers of cardboard on top of my garden soil to help prevent weeds. What is the down side of doing this?
Thanks for your comments. I'll try the mulch.I put corrugated cardboard down then a few inches of mulch. This is called sheet-mulching. That layer of corrugated is worth about 2 inches of woodchip mulch for weed prevention.
After you spread mulch over the layer of corrugated sprinkle it or let a nice soaking slow rain get it wet. Until you do it will be a real slip hazard and a dog doing zoomies around the yard will clear out large areas of mulch.
Why would you spread a thin layer of dirt over cardboard? This will just make a weird layer of isolation between the ground and the top layer. That top layer will then quickly dry out in the sun or wash away with a heavy rain.
Cardboard, woodchips, paper (aka compost browns) don't leech nitrogen from the system but they will lock up the nitrogen in the short term or first few years. This is why you never rototill a garden where you use deep mulch practice with woodchips.
I am in full agreement with this point cpp (I would rather call you Sid or Fred or Joe) I would always prefer to use natural woodland or homemade compost, chippings and well rotted leaf mould than any matter that could be impregnated with suspect chemicals.I just read a post on gardenprofessors that basically said NEVER use cardboard, of any kind, in a garden. There are lots of ‘forever chemicals’ in all types. Just use chips from arborists. Up to 12” deep for weed prevention.
Sorry about my earlier recommendation.
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