Organic matter retains moisture and provides a source of nutrients, which is important in sandy soils. In clay based soils, organic matter binds the small clay particles together creating larger pore spaces for air. Drainage and structure is improved. The pH of the soil is a measure of the acidity or alkalinity of a soil. Most vegetable crops grow best on soils between 5.5-7.0 pH. With careful management, soils as low as 5.0 and as high as 8.0 in pH, can still be productive.
Nutrient availability is dependent upon soil pH levels.
Even though soils may not be deficient in minerals, plants may still exhibit deficiencies depending on the soil pH, because minerals may be tightly bound or held in an unusable form.