ABSTRACT
As mentioned above, a principal objective of tillage is to develop good physical condition in the soil for plant growth-or good tilth. Soil with good tilth has a wellaggregated structure. Aggregates are small, preferably sand-sized, structures formed by arrangement of soil particles into groups that are held together tightly. Sand-sized aggregates formed from clay impart good tilth to this fine-textured soil. These soils will be crumbly and loose or friable. With sandy soils, development of good tilth is not of the concern that it is with clayey soils. Sandy soils are called light soils because of their ease of tillage and possess good tilth naturally. Gravel-sized and larger structures are called clods and impart poor tilth. Cloddy soil usually does not provide good conditions for germination of small-seeded crops. Cloddy soils result from the compression that results from tillage of wet, fine-textured soils and the failure of the particles to break into small aggregates.
