Why Do Hard Lumps Come Up Out of the Ground in the Spring?

Soil Types

• Soil texture is classified by the amount of sand, clay and silt the soil contains. Sandy soil is coarse and gritty and doesn't hold moisture and nutrients. Clay soil is smooth to the touch and feels sticky when it's wet. Clay is fine-textured and has the capability to hold nutrients, but it becomes compacted and doesn't allow water and air to pass through because it's so dense. Silt's texture is between clay and sand. When silt is wet, it feels somewhat smooth. It isn't gritty like sand, but it doesn't stick together like clay. If your soil is lumpy in the spring, then chances are good it has a high level of clay.

Cohesiveness

• Soil's cohesiveness, which depends on the amount of air and water in the soil, has much to do with the soil's texture. Because clay soil is finely grained, it is very cohesive and forms dense clumps when it's wet. Because it contains little air, clay soil doesn't crumble easily and the lumps are difficult to remove when the soil dries. Granular soil, including sand and silt, has a low clay content, is coarsely grained and isn't cohesive. It doesn't form clumps, or lumps, when wet and crumbles easily when dry.

Loam

• Loamy soil is best for gardening because it combines relatively equal amounts of clay, sand and silt. The clay content ensures that the soil holds moisture, but sand and silt prevent the soil from clumping, allowing both air and water to permeate. Soil that consists primarily of one soil type -- sand, silt or clay -- benefits from the addition of organic material such as compost, rotted animal manure or mulch such as chopped leaves. In addition, clay soil is often improved by the addition of sand. No more than 2 inches of organic matter should be added in a single year, however. Soil improvement is an ongoing process.

Timing

• Attempting to work soil too early in spring often contributes to lumpy soil. Working the soil too early is especially problematic if the soil is clay or silt because it forms bricklike lumps that damage the soil structure. Be patient and don't plow or dig the soil until it has time to dry. To determine when the soil is ready to be worked, squeeze a handful of the soil. If the soil forms a clump that holds together, it's too early. Wait until squeezed soil falls apart easily.