I live in North Carolina and the soil here has an extremely high clay content. I have used soil conditioner that consists of composted pine fines to amend the soil. It does an excellent job of breaking the clay here and things now grow like mad in it. I also spread compost and dig it in as well.

What other things are people doing to make heavy clay soils productive?


3 Answers 3


Just to round off the sterling advice already given: if it is available, I would definitely add plenty of well-rotted horse manure (not farmyard or cattle manure, which is more suitable for amending light soils). Over time, horse or stable manure - preferably one that contains plenty of straw, rather than wood shavings - will open up the soil structure, and improve aeration and drainage

  • 1
    Yes, horse manure is great for poor soil. It's done wonders on my poor soil, even with a wood-based stall bedding. (The pumpkins don't even need the soil -- they pop right out of the manure/compost pile and grow like mad.) If you have a truck, with a little looking around you'll find someone willing to part with a couple of truckloads for free. Fair warning: you'll probably import a lot of weed seeds.
    – bstpierre
    Commented Jul 6, 2011 at 0:57

I live in the St Louis area so my soil is also very clayey.

I make 5 gallons of compost tea each week (from late Spring to earlier Autumn "Fall") and apply the 5 gallon batch to the front garden one week, then the following week apply a new fresh 5 gallon batch to the back garden. I repeat that cycle for the period given previously.

I have been doing this for 2 years now, and without question I have noticed a massive increase in worm activity eg lots of worm castings on the surface of the soil.

The more worms & good micro organisms you have in your soil, the better your soil will become (at least that is my belief).


Compost sounds like the main thing you want. This will primarily add nutritional value to the soil (to be fair clay minerals can hold all sorts of mineral ions - but no humus or water holding ability) but also improve drainage, digging, and it will be easier for roots to penetrate.

Over time the compost will break down so you will probably always adding it, just at a much lower rate in future years.

I would also add some sandy soil for the first few years - this will do a good job of improving the drainage.

@Mike Perry's advice sounds excellent: The worms will improve the soil fertility, but also do most of the mixing. They'll do a better job than you ever can and help save some hard work!!

  • FYI I've read that you have to add lots of sand (45-55% to total soil) to make it work. Otherwise the clay will just stick to the grains and make everything more solid.
    – Dano0430
    Commented Jul 7, 2015 at 18:28

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