Posted by: Micaela Truslove
CSU Extension, Broomfield County
Being an exuberant gardener is a good thing, but when it comes to soil, patience is certainly a virtue. It takes years to improve garden soil, and one wrong move may undo all of the hard work and hours spent loosening, turning and amending. That wrong move is often working the soil while it is too wet.
Ideally soil is made up of four different components: about 45% mineral content from degraded rocks, about 25% water and 25% air, and about 5% organic matter. Notice that the ideal soil has water and air in equal measures. Roots require oxygen to survive and thrive, and they will only grow where oxygen is present in sufficient quantities.
Photo credit: http://www.emc.maricopa.edu/faculty/
When wet soil is worked, whether it is walking on the soil surface, digging a hole to plant some seeds or tilling in organic matter, the air is pushed out as those pore spaces are pressed together and compacted, damaging the soil's structure. If you've ever tried to dig in clay soil that has become compacted and baked solid, you know that it is not unlike trying to dig into your concrete driveway.
To avoid this, wait until the soil has dried sufficiently before you begin to work in the garden this spring. There is a simple way to test whether or not the soil has dried down enough to work: take a small handful of soil from a depth of about 3". Squeeze the soil into a ball. If water runs between your fingers when you do this, it is definitely too wet. If the soil forms a ball, drop the ball on the sidewalk, or if you are more coordinated than I am, throw it up in the air and let it land on your palm. If the ball shatters, the soil is dry enough to work; if it doesn't, give it a few more days of dry weather and test it again.
Read more about soil texture, structure and pore space here, and remember to protect those pores by waiting until the soil is dry enough to work this spring!