# Water movement in Soils



## wors (Feb 2, 2019)

More questions about clay, hard soil, and adding sand to existing soil are being posted. This is one the best videos that illustrates how water moves in soil. It shows having a fine material over coarse material. It also shows organic matter mixed in with soil verse a sand channel being closed off. Some people on the forum suggest aerating clay soils and backing filling with sand. If the holes get covered over time with thatch/soil then the holes don't help but hurt.

Hope this helps people.

https://www.youtube.com/watch?v=DmTNFIEc2VA


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## KoopHawk (May 28, 2019)

That was actually quite fascinating.


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## CarolinaCuttin (Sep 6, 2019)

Pure water has a very hard time moving from small pore spaces to large pore spaces. You may have seen the gardening myth debunkers that use a clear container and fill the bottom half with gravel and the top half with a potting soil. When water is added, the water gets down to the gravel layer and stops filtering through. Hydrogen bonding causing cohesion and adhesion is responsible for this phenomenon.

Add a wetting agent to the soil or the water and everything changes: the expected response is achieved and the water drains through. Wetting agents interfere with hydrogen bonding and allow free movement across a variety of pore space sizes. I'm a big advocate of wetting agents for this reason.

Sand can be especially problematic in soils because it can become coated with hydrophobic organic material. Filling aerification holes in a clay lawn with sand is probably not helping. Unless you are leveling your lawn or sand capping it's probably better to fill aerification holes with a good compost or topsoil mix.


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## wors (Feb 2, 2019)

CarolinaCuttin said:


> Pure water has a very hard time moving from small pore spaces to large pore spaces. You may have seen the gardening myth debunkers that use a clear container and fill the bottom half with gravel and the top half with a potting soil. When water is added, the water gets down to the gravel layer and stops filtering through. Hydrogen bonding causing cohesion and adhesion is responsible for this phenomenon.
> 
> Add a wetting agent to the soil or the water and everything changes: the expected response is achieved and the water drains through. Wetting agents interfere with hydrogen bonding and allow free movement across a variety of pore space sizes. I'm a big advocate of wetting agents for this reason.
> 
> Sand can be especially problematic in soils because it can become coated with hydrophobic organic material. Filling aerification holes in a clay lawn with sand is probably not helping. Unless you are leveling your lawn or sand capping it's probably better to fill aerification holes with a good compost or topsoil mix.


Good points above. The compost works and helps because it is creating macropores with aggregation of clay particles.


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## JerseyGreens (Aug 30, 2019)

20min mark why we should always roll in new topsoil during a Reno. I've been rolling nearly every evening and I can seriously tell I'm removing air holes under my new topsoil.

This was a great timed video for me as I'm having seriously wet areas of my Reno vs dry areas. It must have to do with the new sandy loam topsoil hitting my native silty loam layer 2 inches below.


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## wors (Feb 2, 2019)

Water moves from larger pores to smaller pores. Rolling will compact the pores at the soil surface helping soil move up into those smaller pores.


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## adgattoni (Oct 3, 2017)

I doubt members of this forum are going to sandcap their lawn and subsequently cover it with topsoil. I believe most of us here are going for the scenario illustrated at 22:30 in the video. A sandcapped top layer with vertical channels going down into the native soil.


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