Decado
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Newspaper Mulch - Nitrogen Leaching?

I put down newspaper mulch, and I did put grass on top. The problem is that I used about 4 layers of newspaper to keep away the grass. Are the lower layers of the newspaper going to leach nitrogen from the soil or will the grass on top take care of the nitrogen?

TZ -OH6
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No, high carbon material must be mixed into the soil so that the environment for the fungi remains constant and there is high contact. A layer of newspapers doesn't have the contact or the moisture holding capacity. Wood chip mulch often does hold enough moisture for quite a bit of fungal growth during parts of the season but usually doesn't cause problems because contact with the soil is in a single thin layer. That is good because it may pull nitrogen from the surface where weed seeds are trying to germinate, but not lower down where the vegetables roots are. Mixing unfinished compost or wood chips into the soil is where you can get into trouble.

garden5
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TZ -OH6 wrote:No, high carbon material must be mixed into the soil so that the environment for the fungi remains constant and there is high contact. A layer of newspapers doesn't have the contact or the moisture holding capacity. Wood chip mulch often does hold enough moisture for quite a bit of fungal growth during parts of the season but usually doesn't cause problems because contact with the soil is in a single thin layer. That is good because it may pull nitrogen from the surface where weed seeds are trying to germinate, but not lower down where the vegetables roots are. Mixing unfinished compost or wood chips into the soil is where you can get into trouble.
Interesting. Some say that having the wood chips on top of the soil does leach enough nitrogen that it harms the growth of plants, while others say that it doesn't. Personally, I'd think that they would have a more detrimental effect on shallow rooted plants like cucurbits than on a plant with a deeper root system, like a tomato.
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TZ -OH6
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Joined: Fri Jul 25, 2008 11:27 pm
Location: Mid Ohio

Several factors involved.... root depth, mulch depth, climate. I found that when mulch was really needed to hold in soil moisture the mulch dried out, as did the top couple of inches of soil, thus killing the fungus inbetween wet periods. Without the mulch, soil drying would have been much worse. Newspaper under wood chips would restrict fungal growth, so tht is an option too.

I have problems with low nitrogen here and there for a couple of reasons tied into using clay soil that has just recently been turned into a garden. It is very easy to see that the plants are not growing and have a bit of yellow on the lower leaves. I just give them a shot of shot of nitrogen. They perk up in a couple of days. It is much easier to deal with the low nitrogen than problems associated with not mulching (dry soil, weeds).

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