Manage Soils to Improve Drainage and Prevent Compaction
Soils with good structure and those that not compacted help expand root systems. Roots hold soil in place to reduce erosion, a leading cause of water pollution. Soils that are not compacted allow for increased infiltration of rain and irrigation water.
Soil management is important to healthy plants and healthy ecosystems. Following are a few tips for improving residential landscape and garden soils and why it is important for root systems and plant health.
When reading about the growing needs of plants, it almost always states plants need a well-drained soil. One reason well-drained soils are important is because plants need oxygen along with water. A well- drained soil is also key to well established root systems.
The oxygen plants use in metabolic processes is taken up by roots from soil pores. If a soil is not well-drained, and remains saturated for too long after rainfall or irrigation, water displaces oxygen in soil pores and plants are negatively affected.
It is fine root hairs attached to larger roots that do most of the job of absorbing water and nutrients. Feeder roots are continually dying and being replaced. If soils remain low in oxygen for too long, these fine roots reduce or stop functioning and die at a more rapid rate.
Root growth and plant health can be increased by using soil management practices that improve drainage, especially after construction and when installing new lawns and landscape or garden beds. These include incorporating organic matter and using physical disruption of soil through spading, aerating or tillage to relieve compaction.
To reduce compaction, avoid driving, walking on, or working wet soils. Compaction compresses soil pores and restricts movement of oxygen and water into soil. Also avoid tilling soils too much or too frequently, especially with rototillers. This harms soil structure and can reduce drainage.
A key practice for improving soil drainage is incorporating organic matter like compost or well-rotted manure. Organic matter improves soil structure by increasing soil aggregation which allows for more and varied pore sizes.
Soil aggregates are groups of mineral particles that bind together. Aggregate stability is the ability of soil aggregates to avoid disruption, such as by water. Soils with high organic matter content have greater aggregate stability.
When incorporating organic matter, the general rule of thumb for compost is to spread a two to three inch layer over soil and work it in about six inches deep with spading or tillage. Avoid over-tilling, especially with a rototiller. Using a rototiller too much or too often breaks down soil aggregates.
Another way to increase organic matter in annual flower beds or vegetable gardens is the use of green manures or cover crops. These are grains, grasses or legumes that are sowed in fall, then mowed or killed with glyphosate in early spring before they go to seed for a no-till system for gardens.
The soil is the foundation of root growth and plant health and part of the solution for reducing impaired water ecosystems. While we can select the best plants for our sites, if we plant them into compacted soils with poor drainage, we can’t expect them to perform well or best provide ecosystem services.
This article was reviewed by Sarah Browning