Ask a Master Gardener: More ways to improve garden soil

Dhruba Dhakal, MU Extension horticulture specialist, had an excelent article on improving garden soil. Here is part 2 of the article.

Soil improvement in the garden (Part 2)

The most important resource for garden plants is soil. Soil is an unconsolidated material on the earth surface which is made up of inorganic (mineral) materials and organic matter. It is a living ecosystem containing a large number of microorganisms, macroorganisms (such as earthworms and insects) and plant roots. Soil holds nutrients, air and water required for plant growth and development while also providing structural support to the plant roots. Gardeners want to make improvements to soil for better plant growth and development. There are some methods by which soil can be improved in the garden.

Plant cover crops

After harvesting the crop in the fall, planting a cover crop is a good option to improve soil organic matter. Cover crops have many benefits in the garden soil including covering soil and reducing erosion, adding organic matter content to the soil and reducing weed infestations. Cover crop roots secrete enzymes and other organic compounds which maintain or increase the population and activity of microbes in the soil. Common garden cover crops are cereal rye and winter wheat which overwinter and regrow in the spring. Mow or kill the cover crop in early spring before planting garden crops. Seeding oats, tillage radish and turnip, which winter kill, is another option. Planting legume cover crops such as Austrian winter pea is an option. Legumes fix nitrogen from the air due to a symbiotic relationship with rhizobium bacteria in the root nodules. These legume cover crops add nitrogen to the soil after they die if allowed to grow well into the spring.

Use mulch

Using crop residues such as wheat straw and other crop straw as mulching materials are also a good option to increase organic matter content, reduce soil erosion and conserve moisture in the soil. Mulching provides microclimate for soil microorganisms and macroorganisms such as earthworm. We see many earthworms under the mulching material. After decomposition, organic mulch adds organic matter to the soil. Mulching also reduces weed emergence in fall and spring.

Minimize chemical use

Herbicides, insecticides, fungicides, and bactericides not only kills weeds, pest and pathogens but also kill beneficial soil microorganisms and insects in the soil. It is recommended to consider alternative pest and disease control measures in the garden. Some of these methods include cultural, mechanical, botanical and biological. Weeds can be removed by hoeing and hand pulling when in early growth stages. Low-impact pesticides which are microorganism friendly options such as horticultural oils, insecticidal soap and Bacillus thurgiensis (Bt) can be used. Hand-picking larger bugs from the plants and dropping in soapy water is another eco-friendly option. Physical barriers such as row covers and mesh nets keep pests out of the garden. Selecting disease-resistant plant varieties helps minimize problems and the use of pesticides. Crop rotation each year reduces disease and pest infestations. Collecting and destroying disease and insect infested plant parts help minimize issues in the next crop growing season. Including legume garden crops such as green bean, cowpea and peas add nitrogen to the soil.

Happy gardening!

Peter Sutter is a lifelong gardening enthusiast and a participant in the MU Extension's Master Gardener program. Gardening questions can be sent to [email protected].