Most of our region's soils are clay-based. While re-doing some foundation planting over the weekend, I discovered several deposits of clay. It's kind of a nasty word for those who have been trying to improve this soil condition for years. And it really does take years of incorporating organic matter [compost]. But there are benefits to having clay soil that shouldn't be overlooked.
Clay soils hold moisture. That's important in our arid climate. Clay soils also have reservoirs of minerals and they attract and hold minerals. That means less fertilizing is needed for most plants because minerals are already available. Clay soils are stable, so plants get a better "grip" through their root systems. Downsides: when they dry out, they are like trying to chip through pottery. If they become too compacted, roots can't penetrate and minerals are not available. In addition, when compacted, tiny areas for air circulation are cut off - and plant roots need those little pockets to access oxygen. The soil should be amended for optimum plant health. Dig down about 12 inches and break up the clods of clay, mixing in compost and maybe a little manure. A rototiller is handy for this, or when putting in a new plant, do a one-foot square by hand - taking the approach of improving soil a little bit at a time. Bottom line: Don't despair about clay soil. It has benefits and can be improved.