Sandy soil is coarse and gritty to the feel and water moves through it quickly, so has low water holding capacity. Sand is poor in nutrient content.
Sandy soil can be improved by regularly adding organic material, such as compost or well-rotted manure. This will help improve (slow down) drainage, increase the water holding capacity, and increase plant nutrients.
Clay soil is reddish brown and is fine and powdery when dry. Water moves through it slowly, so it has high water holding capacity; typically, too much. Clay soils can be rich in plant nutrients, but the pH is often too high or low, so those nutrients are not available to plants.
Clay soil can be improved by adding organic material, such as compost or well-rotted manure. This will improve (increase) drainage and provide more appropriate water holding capacity. Organic material will also lighten heavy soil.
Loamy soil is dark brown and contains clay and sandy soil in moderate proportions with some organic material. Water moves through it at a moderate rate, so has moderate water holding capacity. It is rich in plant nutrients. Loamy soil is ideal for growing healthy grass.
Think of pH as the mouth to your grass by which it consumes plant nutrients. The pH scale ranges from 0, highly acidic, to 14, highly alkaline. The mouth of your grass is “wide open” when it has a pH of 6.0 – 7.0, which is neutral and ideal for growing healthy grass.
Grass grown in soils that are too acidic or too alkaline cannot consume any plant nutrients, whether they occur naturally in the soil or are applied in the form of fertilizer. If you are applying fertilizer to your lawn without knowing the pH to your soil, you could well be wasting your money. Don’t do it.
To improve soils that are acidic (below 6) you will need to add lime (calcium carbonate) to move the pH to neutral. To raise soil pH by one point in a typical sandy loam soil, spread crushed limestone in the fall at a rate of about 50 pounds per 1,000 square feet unless your liming product recommends a different spreading rate.
To improve soils that are alkaline (above 8) you will need to add granular elemental sulfur to move the pH to neutral. To reduce soil pH by one point, say from 8.0 to 7.0, spread elemental sulfur with your garden spreader at the rate of 20 pounds per 1,000 square feet unless your sulfur product recommends a different spreading rate.