I follow the same practices in my garden year after year. In the spring after the soil has time to dry out, I go out and rototill, making sure to till in my fertilizer. After planting my seeds and transplanting the plants I have already started or purchased, I make sure to water everything in. I set up my walls of water, put cages around my tomatoes and let nature do the rest. When the seeds come up, so do the weeds, and I spend the summer weeding the garden waiting for the harvest. It has always worked, why change what is working?
This past summer, I began working at the University of Idaho as an extension educator and started hearing some things that got me thinking about the things I do in my own garden. Just because something is working does not mean it cannot be improved on. Sustainable practices that are being accepted increasingly by agricultural producers like no-till or limited-till have struck a chord with me and made me wonder if I could apply those principles to my home garden. The answer is absolutely they can, but should I?
Advantages of Tilling
Idaho winters are cold. One great advantage of tillage is it warms the soil up. Seeds will refuse to germinate until the soil temperature is within its range of tolerance. If I can warm the soil earlier, logic says I can start seeds earlier and that I can harvest earlier.
Heavy clay soil suffers from compaction. Plants need enough air and water space in the soil to grow properly. Tilling the soil breaks up large aggregates of soil and supplies a fine seedbed for planting.
Nutrients and oxygen come into plants through the roots in the soil. Tillage can help incorporate organic matter and oxygen into its profile, so plants have access to the nutrients they need to survive.
Disadvantages of Tilling
Soil structure is the way individual particles of sand, silt, and clay are assembled. Soil structure affects the water holding capacity, nutrient availability, aeration to plants and microbes, and resistance to erosion and compaction. In gardens, rototilling breaks up soil structure, exposing it to air and sunlight which diminishes soil moisture. Over-tilled soils dry out more quickly and create a ‘crust’ on the soil surface.
The soil acts as a seed bank for weed species. Tilling the soil brings seeds to the surface that were too deep to germinate and lay dormant for years. Every time you till you bring a new generation of seeds to the surface.
The biggest reason to avoid tillage is that it disrupts the soil food web. Billions of microorganisms in the soil create microscopic pathways to transport water and nutrients and increase the soil’s ability to drain excess water while retaining proper moisture levels. The beneficial bacteria and fungi in the soil are disturbed through tillage operations and may take years to recover.
Added benefits of reducing or eliminating tillage in your garden include:
Slowing decomposition of organic matter
Improved natural aeration, water percolation into the soil and water drainage
Improved crop root development
Improved water holding capacity for longer periods of time
Helps soil keep carbon
How can I implement no-till or limited-till in my garden?
No-till gardening includes two basic principles, narrow raised beds and mulching. Put away the rototiller, start the spring out by deciding where your beds will be. Constructing raised beds will reduce labor in the long term. A raised bed’s function is to define the planting space by elevating it above the ground around it. This is important because you do not walk on the planting bed. Walking on the bed increases soil compaction and increases the need for tilling. Make sure your raised beds are no wider than you can reach, usually 3 to 4 feet. The key is to separate the raised beds from walkways.
Another key to no-till gardening is covering the soil with some type of mulch. This can be accomplished by using a variety of materials.
Clear polyethylene plastic helps absorb solar radiation, warming the soil. Black plastic is not as effective in the spring but can be an effective tool in the fall to keep the soil warm. Black plastic only results in warmer soil temperatures when in contact with the soil. Landscape fabrics can also be used as mulches; however, they do not hold the heat like plastics do. My suggestion for gardening is to use landscape fabrics on planting beds with holes cut for your plants.
Three inches of shredded bark, compost, wood chips, sawdust, pine needles, and even cardboard can act as mulch. Any of these options work well in planting beds.
If you are converting a section of lawn to a garden use black plastic as mulch for 3 months to a year. It will kill most of the weed seeds and unwanted vegetation. When you are ready to plant your garden, remove the black plastic, use a broad fork to loosen the soil where you will plant your seeds or transplant starts. If you are using landscape fabric, fasten it in place over the planting bed. If you are using organic mulch, layer it over the planting bed. In addition, walkways should be mulched to reduce the impact of weeds.
In the fall after harvesting your crops, instead of pulling the plant roots and all out of the ground, cut the plants off at the roots and allow the roots to decompose in the soil. Most of the microbial activity in the soil takes place in the root zone. In the spring if the roots are still there, they can be removed at that point. Landscape fabric should be removed during the winter. This is a great time to layer compost on top of the soil. In the fall up to 12 inches of compost can be layered on plant beds. This suffocates existing plants and beds are ready for planting in the spring. Any incorporation of compost can be done in the spring or the fall. If you are using bark or wood chips as mulch in your garden, understand they break down very slowly. I suggest removing them in the fall and putting compost down on the planting beds.
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