The Effects of Rototilling on Soil

Rototilling Basics

• Rototillers are usually gas operated, though there are some light-duty electric models. There are rear-tine or front-tine models, each cultivates the soil to a depth of 8 to 10 inches as the tines rotate. The intent of rototilling is to break up compacted soil, loosening it and smoothing out its surface. Rototillers are also used to break new ground and remove weeds.

Pros

• Well-aerated soil with few heavy clods makes for healthier plant roots. Working compost and manure into the soil with a rototiller can improve both soil texture and fertility. The rototiller helps work amendments in consistently and to an even depth. Tilling also creates a smooth bed for seeding. Rototilling takes less effort from the gardener than digging, though it does require significant upper-body strength to operate the machine. Once the soil is loose and smooth, it is easier to rake up and compost weeds and other debris.

Cons

• Working the soil when it is wet can damage soil structure by reducing pore space in the soil. When the soil has any clay in it, it can also dry in hard clumps or crust over, making it difficult for water, roots or young seeds to penetrate. Churning through the soil with rototiller tines -- even in relatively dry soil -- also collapses the tunnels and layers of nutrients created by earthworms, roots and soil microorganisms. In addition to eliminating some of the worm and insect population and their work, rototilling can also bring dormant weed seeds up to the surface of the soil where they germinate, right as you are preparing to plant.

Options

• Layering amendments over the soil and digging it in by hand is less disruptive to the soil ecosystem. Chopped leaves and other organic matter can be layered over the soil in the fall and worked in with other amendments in the spring after soil is dry. Soil should be dry enough that a ball of soil breaks easily on the ground when dropped from waist height before rototilling or digging in amendments. Cultivating releases nitrogen in the soil as it introduces air. Loosening soil or incorporating amendments in the fall wastes the nitrogen if you aren't planting a winter garden. When you need to cultivate -- either by hand or with a rototiller -- cut the area of soil that you work down to just the row or area where the plants grow.