Tips for Amending Problem Soils (2024)

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How to Amend Rocky Soils

Rocky soilsoftenlacknutrientsthatplantsneed,and they’re not good at holding water. They’re also hard to dig or till. Removing the rocks will makecultivating your garden easier and helpplant roots penetrate the soil.

Onceyou’ve removed as many rocks aspossible,use a shovel to break upthesoil to a depth of about eight inches. Next,work in three to fiveinches of organic matter, such ascompost or well-rottedmanure.

If you havemore rocks than you canremove, rake a layer of topsoil to your garden spot orplantyourflowers or vegetablesin raised bedsfilled with good organic planting soil.

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How to Amend Clay Soils

While you can see rocks in your soil, it’s not as easy to know ifitcontains clay.Clay doesn’t let waterdrainreadily,sopools ofstandingwaterare often signsof its presence.When clay soil dries out, it may crack.

To test forclay,use a garden trowel to dig up a smallhandfulof subsoil(the layer of soil underneath the topsoil). Moistenit withsomewater,shape it into a ballanddrop the ball onto the ground. If it stays in a clumpand doesn’t break apart, you have clay soil.Repeat this test with samples from different places in your garden, since you may not have clay everywhere.

You can improve clay soil, but don’t work it when it’s wet, and avoid walking on it so it doesn’t become compacted. When it’s dry, addthree to fourinches of organic materials, such as compost, leaf moldorwell-rotted manure(not peat moss),and work them into the soilaboutsixinches deep.Mulch the soil withbark, wood chipsorsome other type of mulch that decomposes slowly. Over time, the sun and rain break down the mulch, which will also improve your soil.

Growing a cover crop from seedcan also help. Try clover, winter rye or legumes to build up healthy soil.Sow the crop inthefall, after your garden is finished. Itwillalso help control erosion and keep weed seeds fromsprouting. Covercrops can be turned underto add more organic mattertothe soilwhenyouplant again in spring.

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How to Amend Compacted Soils

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How to Amend Sandy Soils

Sandy soils aren’t good at holdingwateror nutrients, but they’reeasy toidentify.Sandfeelsgritty andwon’t form a ball in your hand.

Fortunately,sandy soil iseasy to dig, so work intwo or three inches ofpeat moss or perlite to help it retain water.Toaddnutrients, work in compost, leaf mold, well-rotted manure or other organic matter.When you fertilize, choose a slow-release product. Liquid fertilizerscanmovethrough sandy soil too fast to benefit plants.

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How to Amend Saline Soils

Plants can fail to thrive or die in soils with too much salt content. Saline soil can be present in arid regions, in areas with shallow water tables, near oceans or where minerals have weathered and broken down. Road salts can also accumulate in soil.

Improving saline soil is a challenge, so ask your County Extension Service agent for advice if this is a problem in your garden. Extension agents can also help you find salt-tolerant plants and suggestorganic materials, if any, that may help improve your soil.

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What is Soil pH and How Do I Amend It?

Soil pH refers to the acidity or alkalinity of soil. It’s measured from zero to 14. Acidic soils have a pH below 7.0,whilealkaline soils measure over 7.0.Seven is neutral.

Soil pH is important because it affects the ability of plants to use nutrients.Most plantswill do finewhen the soil pH is between 6.0 (slightly acidic)to 7.5 (slightly alkaline).However, some plants, such as blueberries and azaleas, need acidic soil, and some trees, shrubs and perennials do better in alkaline soil.

A pH meter or test kitlets you measureyour soil’sacidityoralkalinity so you can amend it, if indicated. It’s a good idea to take soil samples from various places in your garden and combine the measurements to get your average soil pH.Follow instructions in the soil test kit you purchased or you can use a soil test kit from your local County Extension agent.

If your soil is acidic,usegroundlimestonetoraisethepH.If possible, apply it two or three months before planting, so it has time to work. Wood ashes from untreated wood will also raise pH. Spread them over the soil in the winter and work them in the next spring.

Ifyour soil is alkaline, aluminum sulfateor sulfur willlower its pH.Aluminum sulfate changes the pH right away. Sulfur works more slowly.Changing the soil’s pH usually requires several treatments, so retest until you reach the pH you need. Also, retest when you plant a new garden.

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Top-Dress Your Garden

Again, it's recommended that you amend your soil on a regular, consistent basis with organic matter. Amend your pH as the soil pH testing indicates.

Vegetable gardens benefit from a top dressing of organic compost in spring and/or fall or in mid-season. Simply pull away anymulch and spreadtwo to three inches of compostor well-rotted manure over the soil.Then replace the mulch. Youdon’t need to work the compost into thesoil;itwill break down naturally andreleasenutrients.As a bonus, top dressing can help discourage weeds from growing and help the soil retain moisture.