A soil test indicates what nutrients are in the soil and what nutrients are needed. A soil analysis from NCDA lists the amount of nutrients in the soil and gives recommendations for improving the nutrients for landscape plants. After the initial soil test, soil should be tested every three to five years to make sure the fertilizer program is on target. The effectiveness of fertilizer applications depends on soil properties such as texture, organic matter content, drainage, and pH. Soil particles are grouped by size and designated as sand, silt, or clay. Sand is the largest particle size, and clay is the smallest.
Soil texture varies with the different proportions of sand, silt, and clay on each location.
In general, soils with a greater portion of silt and clay retain more water and nutrients than those soils composed mostly of sand particles. Soil organic matter also influences soil productivity. Organic-matter additions to soil may also provide nutrients as they decompose, or they may increase the tilth of the soil by amending or modifying the soil structure to promote water infiltration and root penetration. Soil drainage is critical to plant health. The soil's ability to hold water must be balanced with its ability to retain enough oxygen for plant growth.