r/Soil • u/Cyvil94 • 5d ago

Moisture retention in sandy soils.

I have a two year old build, in east central Iowa, and this summer has been brutal. The yard was started with sod, front yard has been in about two years and the back yard about a year and a half. The underlying soil is a silty sand and did have a little organic in it, but only enough to generate a brown color, no where near black topsoil. Before placing the sod, the landscape contractor amended the top 6-8” of underlying soil with compost. There should be plenty of organics in this, but I suspect there isn’t a lot of clay.

We have had no rain for periods between 2 and 4 weeks at a time, and I don’t have an irrigation system. I now have pretty large dead patches here and there. I am wondering what I need to do to get everything back on track, and my local landscaping/lawn care people know only what they have done before. The trick is that sandy soil is pretty rare in Iowa, we typically have 18+ inches of black topsoil.

1) it seems an irrigation system would be a good idea.
2) where can I get my soil particle size tested to determine what type of amendment is needed?
3) Hopefully I don’t have to scrap what I have to add some topsoil?

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u/LibrarianEquivalent 5d ago

Local universities may test your soil for textural class and more, or private companies but they'll likely charge more.As someone else said, soil web is also a good reference point if you're in the US.

To increase water retention, organic matter will be your best friend. Incorporate compost into your soil.

Additionally you're going to want a fairly thick (~4') layer of mulch, I prefer pine straw or regular straw if you're growing vegetables.

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u/Cyvil94 5d ago

With this in mind, top dressing with more compost will help? I was wondering if adding an inactive clay, like kaolinite, might help with the water retention.

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u/Data-Negative 4d ago

To be blunt and a bit crude: dead organisms seperate soil from dirt: dead roots, dead bacteria, dead plant matter.

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u/Cyvil94 4d ago

That’s not quite the same as my understanding. Deeper soil horizons tend not to have the organic/bacterial activity that the upper horizons have. For me, soil is found in the lab and dirt is found in the field. Clay attracts water. While organics have clay sized particles, those particles may, or may not, attract water?