Soil Building for Watershed Health

Rachel Davis, Water Resources Extension Agent, Clemson Extension Service

April 2017

Many people think of soil as they are washing red stains out of jeans, digging in the garden, or seeing the long rows carved into the earth and sprouting a favorite summer vegetable. In all of this appreciation, we may be underestimating the innumerable benefits of what’s underfoot. The state of soil also contributes to the effects of pollution on our environment and how well our communities can adapt to seasonal rainfall patterns. As impervious area grows in South Carolina and throughout the United States, soil loss and compaction reduce opportunities to naturally protect water resources. Whether you are a property owner, property manager, community staff, parks manager, builder, or farmer, you can build better soil health and protect our shared waters.

The Importance of Healthy Soils

Figure 1. Healthy Soil Info-Graphic (USDA, 2015)

Healthy soils contain organic matter, have good structural “aggregates,” are covered to prevent erosion, and are teeming with microbial life. Healthy soil can store excessive irrigation and rainwater, mitigating the effects of flooding and drought; increase crop production and improve landscaping, minimizing the need for fertilizers and pesticides; and help prevent water pollution and its negative consequences for humans and the environment.

  • Flood mitigation. Uncompacted soil has pore spaces between the soil particles and aggregates of soil particles that hold both air and water. This allows water to seep into the ground, creating storage for what otherwise could result in increased floodwaters. According to a 2008 report by the SC Department of Natural Resources, 13% of our state’s land area is subject to flooding and over $416 million has been paid in flood insurance claims since 1978 (SC DNR, 2008). In 2013 and 2015, many southeastern states, including South Carolina, experienced above average amounts of precipitation after several years of drought. Current climate predictions for the Southeast indicate more extreme weather conditions: an increase in heavy downpours with longer, more intense droughts between storms (SCDA, 2015).
  • Manage resources during drought. In eight of the last ten years, our state has experienced drought conditions. As our population grows, the demand on water resources and subsequently the possibility of water shortages increases. Healthy soils can store water longer, mitigating the damaging effects of droughts. 
  • Increased crop production and improved landscaping. Whether in an agricultural field or a home landscape, plants benefit from the increased organic matter, better structure, and microbial life found in a healthy soil. Potentially better quality and greater crop yields result, along with savings due to less need for chemical additives. This impact can be significant depending on the soil building techniques that a farmer uses. Home gardeners can benefit similarly, by reducing their need for fertilizers, pesticides, and irrigation.
  • Pollution prevention. The billions of organisms that live in healthy soil, including microbes, fungi, algae, and insects, help break down nutrients into usable forms that plants can uptake through their root systems. These nutrients may otherwise be washed away to local streams, rivers, and lakes during the next rainfall event, leading to algae blooms, possible fish kills, and an overall decline in water quality. Healthy soils, therefore, can remove pollution from our environment, possibly saving communities money for monitoring and repairs. Soil microorganisms also naturally breakdown many pesticides: what is not used on the target organism (weeds, pest insects, diseases) may be broken down by soil microbes. Healthy soils promote a diverse soil microbe community, and thus can help to protect unused applied pesticides from being washed away or leaching into our water resources. The minerals and organic matter that make up a soil can also bind with certain pesticides, reducing the chance of loss to groundwater or surface water runoff. Another major source of water pollution is sediment due to soil erosion. The less soil is disturbed, and the more it is covered by plants or mulch, the more water will infiltrate deeper into the ground. This will reduce the amount of sediment and chemicals (nutrients and pesticides) carried by stormwater runoff. 

Table 1. Practices and Benefits for Agriculture

Practices ->

Benefits

 Plants cover crops

Use no-till or conservation-till methods

Use fertilizers and pesticides purposefully

Reduces erosion

X

X

Maintains soil structure; reduces soil compaction

X

X

Increases organic matter

X

X

Increases water retention

X

X

Keeps soil microbes alive

X

X

X

Reduces the need for fertilizing 

X

X

X

Reduces the need for irrigation

X

X

Recycles nutrients into the soil

X

X

Reduces harmful chemicals in waterways

X

X

Creates a good growing environment

X

X

Cost savings

X

X

Actions to Protect and Improve Soil Health

Agriculture. Those involved in one of the 25,000 South Carolina farms on almost 5 million acres across the state (US Census, 2015) know how essential soils are to crop quality, yield, pasture health, and more. Cover crops, no-till, and conservation-till methods have proven to decrease the amount of topsoil that is lost; encourage a diverse and abundant microbial community, which ultimately may promote good soil structure; and increase plant available nutrients. Additionally, reducing the amount of fertilizers and pesticides used will also benefit microbial activity and soil structure. These practices will help ensure that the land will have productive yields now and into the future.

Distribution of runoff volumes under natural and impervious conditions (US EPA, 2003).Construction. New residential development has been on a steady rise in South Carolina. In 2014, almost 25,000 building permits were issued for new housing units, up from 15,500 in 2011 (US EPA, 2003). An increase in new construction typically means an increase in impermeable surfaces, which leads to greater volumes of stormwater runoff and poorer water quality downstream. However, if builders and landscapers keep soil health in mind during construction and post-construction, the environmental effects will be lessened. Builders can keep existing plants in place as much as possible, and should limit construction traffic onsite to minimize soil compaction. Also, by adding back enough topsoil and choosing plants that are adapted to thrive under the site’s conditions, new landscaping will look better and be easier to maintain. A soil test will help determine the compatibility for the use and plantings, and which landscaping plants will grow best in the location. If an irrigation system is to be installed, the water source should be tested too. Water quality parameters like pH, salinity, and alkalinity can influence soil structure and impact the soil microbial community and plant health.

Homeowners, property managers, and landscapers. With South Carolina’s population estimated at more than 4.8 million people (US Census, 2015), residential actions have a huge effect on our water resources. Homeowners and property managers can provide nutrients for their lawns and gardens by leaving grass clippings on the lawn and adding in compost. Selecting “the right plant for the right place” and those that will thrive in our climate are critical considerations. More assistance with these plant choices can be found at Clemson’s Carolina Yards program and Plant Database (see www.clemson.edu/cy).  Use of fertilizers and pesticides may be reduced as the soil builds a natural ability to provide nutrients for plants and thrive against diseases.

Table 2. Practices and Benefits for Construction

Practices ->

Benefits

Leave  grass clippings on the lawn

Add compost

Test your soil and follow suggestions

Test your irrigation water and follow suggestions

Use fertilizers and pesticides purposefully

Select fertilizer source based on soil pH

Choose the right plant for the right place

Reduces erosion

X

X

X

Maintains soil structure; reduces soil compaction

Increases organic matter

X

X

Increases water retention

X

X

Keeps soil microbes alive

X

X

X

X

X

Reduces the need for fertilizing 

X

X

X

X

X

Reduces the need for irrigation

X

X

Recycles nutrients into the soil

X

X

X

Reduces harmful chemicals in waterways

X

X

X

X

X

Creates a good growing environment

X

X

X

X

Cost savings

X

X

X

X

References 

South Carolina Department of Natural Resources (SC DNR). 2008. Quick Guide: Floodplain Management in South Carolina. Columbia, SC.

South Carolina Department of Agriculture (SCDA). 2015. About. https://agriculture.sc.gov/about/  (Accessed online 2016)

United States Census Bureau. 2015. Building Permits Survey. http://www.census.gov/construction/bps/stateannual.html  (Accessed online 2016) 

United States Census Bureau. 2015. State and County Quick Facts. http://quickfacts.census.gov/qfd/states/45000.html  (Accessed online 2016) 

United States Department of Agriculture (USDA) Natural Resources Conservation Service. 2015. Healthy Soil is a Heavyweight. Washington, D.C. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/health/?cid=stelprdb1143204 (Accessed online 2016)

U.S. Environmental Protection Agency (US EPA). 2003. Protecting Water Quality from Urban Runoff. Document No. EPA 841-F-03-003

United States Environmental Protection Agency (US EPA). 2013. Climate Impacts in the Southeast. https://www.epa.gov/climate-impacts/climate-impacts-southeast (Accessed online 2016)

More Information

  • From Carolina Yards Online to local workshops to fact sheets, there are many resources for those interested in these soil health and watershed management topics.
  • Carolina Yards (www.clemson.edu/cy) teaches low maintenance landscaping practices and actions to lessen environmental impacts and save money in your yard. A workbook is available for purchase, and one can certify their yard. A database will help identify the most resilient cultivars that are not invasive and fitting for the South Carolina landscape.
  • Clemson Extension HGIC (www.clemson.edu/hgic) offers dozens of fact sheets on soils, plants, and watershed management topics. For water-related fact sheets, see the SC WaterWays series, which includes green infrastructure, erosion control, and other relevant topics.
  • The Center for Watershed Excellence (www.clemson.edu/watershed) offers courses such as the Post Construction BMP Certificate course for engineers and inspectors looking to advance their knowledge of inspection and maintenance of stormwater best management practices and green infrastructure.

With appreciation to content reviewer, Dr. Dara Park, Clemson University.

Executive Editor: Katie Buckley, Clemson University Center for Watershed Excellence.

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SC Waterways is an informational series from Clemson Extension's Water Resources Program Team

Katie Buckley, Executive Editor for SC WaterWays and Director, CU Center for Watershed Excellence

Carolina Clear is a program of the Clemson Cooperative Extension Service. Information is provided by Faculty and Cooperative Extension Agents. Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status and is an equal opportunity employer.