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E. Vinje

Hi Catherine –

It sounds to me like you need to add soil amendments to improve your lawn’s soil texture and structure and adjust its pH, rather than its nutritional content. That’s the domain of fertilizer. Too many lawn programs fertilize heavily without adding amendments, which means that plant roots cannot make the best use of the food they’re given.

It’s a good idea to add organic soil amendments like compost at least once a year, to make sure that the soil itself stays healthy. Sulfur (to lower pH) or lime (to raise it) should only be applied after a soil test, since adding the wrong one will damage your grass and the soil beneath it.

Here’s a quick overview of amendments for your lawn soil.

Compost: if you’re not sure what your problem is, add organic compost. For that matter, even if you are sure, add compost. Compost is the miracle amendment, for it improves all soils. It helps balance pH, making acidic soils more alkaline and alkaline ones more acidic. It improves soil retention in sandy soils and drainage in clay soils. Used regularly, it helps reduce compaction, thus improving soil structure.

Make sure the compost is well-finished and gives off only a rich, earth-like odor. Unfinished compost will not only smell but may rob your soil of oxygen. Best times to apply are in the spring before the grass begins to green and/or in the fall after the grass has gone dormant. Whenever you spread compost, do not apply too much. Compost should be spread no more than 1/2 inch deep over existing lawns.

Raising pH (make acidic soils more alkaline): Add wood ashes or agricultural lime, which can be purchased in any of several forms. For lime to be effective, it must be spread evenly, it must be dampened, and it must be in direct contact with the soil. To meet these conditions, rake, dethatch, or aerate before spreading, and water immediately afterwards. Note: Most turf grasses prefer a slightly acidic soil with a pH value between 5.8 and 6.5.

Lowering pH (make alkaline soils more acidic): Add sulfur pellets which, like lime, comes in several forms. For ground rock sulfur, add 1.2 ounces per square yard to sandy soils, and 3.6 ounces per square yard for any other soil.

Amending Sandy Soils: Organic additions work better than mineral or synthetic amendments to improve drainage and relieve compaction in sandy soils, because organic matter derived from plants and animals holds many times its own weight in water. Compost adds much more than organic matter, being rich in nutrients and micro-organisms, but for sheer unadulterated water retention, peat and sphagnum moss or coconut fiber are the way to go. Mature, composted manures are also excellent.

Amending Clay Soils: Everything said about sandy soils goes for heavy clay soils as well: compost and other organic amendments are far and away the best. They will make clays more porous, which in turn makes them more workable and improves drainage. Sand and gypsum are frequently suggested for clay soils, but many experts question their effectiveness, and they need to be used carefully. With products derived from plants and animals, you cannot go wrong.

Hope it helps!