Frequently Asked Questions
How do I take a soil sample, where do I send a soil sample to get it analyzed, how much does it cost to get my soil tested or how do I interpret the results of my soil test? (See Answer #1 Below)
I am a student and have a project (paper, report etc.) to do about soils (water pollution, the environment etc.). Can you send me some information? (See Answer #2 Below)
I am interested in learning about the special content of North Carolina soil. For example- why does tobacco grow so well, what would have to be done to the soil to make it good for other crops, etc. (See Answer #3 Below)
I have spent many hours searching for information on soil quality and its relationship to the construction industry/ building services sector. However all the sites i find seem to talk of soil quality in relation to farming. Do you have any information on this area? (See Answer #4 Below)
I have been using a product called XXX (septic system addative) for a few years. The problem is, they keep coming out with "a much improved" product. They claim that laundry detergents now have more antibiotics than before and they don't break down as easily. they also contain tricelan which causes buildup in the drain lines. I need to know if these products really work or am I flushing my money down the toilet?(See Answer #5 Below)
Hi. I just returned from a trip to (Louisiana, Montana, Michigan) and I noticed that the soil there was (red, black, brown, grey). Do plants grow better in a certain color of soil? What makes soils different colors?(See Answer #6 Below)
I would like to get some information on peat pods and other above ground septic systems.(See Answer #7 Below)
I am interested in getting detailed information about what plants are acceptable (and not acceptable) to plant on or near septic systems and their leach fields. Any literature you might have or suggested books obtainable locally (Salisbury) would be appreciated.(See Answer #8 Below)
Answers to FAQs
How do I take a soil sample, where do I send a soil sample to get it analyzed, how much does it cost to get my soil tested or how do I interpret the results of my soil test?
The North Carolina Department of Agriculture and Consumer Services offers a soil testing service for North Carolina residents. Please see their web page for more details.
I am a student and have a project (paper, report etc.) to do about soils (water pollution, the environment etc.). Can you send me some information?
I have started building a page with links to sites which may be helpful for students researching a topic related to soil science. Please send me any additional links that you have found useful and would like to share. Also, if you have a specific question about soil that you need help with you can click the "Contact Us" link and send you question in. I will forward your question to the the soil scientist that I think will be most likely to be able to help you.
I am interested in learning about the special content of North Carolina soil. For example- why does tobacco grow so well, what would have to be done to the soil to make it good for other crops, etc?
(from S. Buol) - First, there are over 400 different soils in North Carolina and only a few are good for tobacco. Even tobacco requirements differ between flue cured tobacco and burley tobacco. The requirements for flue cured are the most specific. To obtain high yields of the best quality flue cured tobacco a grower needs to grow a big plant that becomes nitrogen deficient near maturity. This is best done in the well drained Kandiudults of the middle and upper coastal plain areas of the state. The soil conditions best suited are a sandy surface about 10 to 15 inches thick over a sandy clay loam subsoil. The sand surface should have a low organic matter content so the little nitrogen is available through organic matter decomposition late in the summer. There growers provide abundant nitrogen early in the growing season as a soluble inorganic nitrate that is easily taken up by the plant but only enough nitrogen for early growth is provided and the "golden leaf" of maturity is in part yellowing from nitrogen deficiency as the crop matures.
Other crops flourish on almost all of the soils in North Carolina if they receive proper management. Phosphorus fertilizer and lime to correct natural soil acidity are universal requirements in all soils in North Carolina. In general the soils in North Carolina have some of the lowest natural fertility of any soils in the world and prior to fertilizer shifting cultivation "slash and burn" was the farming practice. This was the same practice presently conducted on similar soils in the Amazon jungle and central Africa. Fertilizer has been used in North Carolina for well over 100 years and the cropland soils are better now than they were naturally with respect to crop plant production. For example average corn yields in 1883 were 11.5 bu/ac and in 1992 95 bu/ac.
I would suggest that Mr. XXXX look at the Soil Science Society of North Carolina Web Page: http://agronomy.agr.state.nc.us/sssnc/index.htm (Celebrating a Century of Soil Science) to find information on the Formation of Soils in North Carolina and several other articles. In particular the quote from Professor Mitchell's speech in 1822 about the Soils in North Carolina where he describes slash and burn activities of farmers of that day should be of interest.
I have spent many hours searching for information on soil quality and its relationship to the construction industry/ building services sector. However all the sites i find seem to talk of soil quality in relation to farming. Do you have any information on this area?
(from S. Buol) - The construction/building services industry has many and quite diverse uses of soil and soil material. Therefore no single soil quality rating is satisfactory. All soils are rated in two categories, suitability as a source of construction material and suitability as a site for light construction (small buildings, roads, streets and utilities). Large buildings usually involve removal of the soil and placement of the foundation below what is classified as soil.
The best place to find specific suitability ratings for different soils is in the county soil survey reports. Almost every county in the US has a published soil survey report that contains a map of the county and suitability ratings for the soils found in that county. There are over 18,000 different soils recognized in the US and each county will have from about 30 to 60 different soils identified. Some more and some less. Each soil is rated as to its suitability as a source for roadfill, sand, gravel and topsoil. Also, each horizon (layer) within the soil is identified as to its Unified and AASHTO classification, content of coarse fragments, liquid limit, shrink-swell potential, permeability, pH, and plasticity index.
For on site construction each soil is rated for the following sanitary facilities: Septic tank absorption fields, sewage lagoons, trench sanitary landfills, area sanitary landfills and daily cover landfills. Each map unit (a map unit identifies the soils present and in addition identifies the slope percentage and additional features of the land) is also rated for frequency and duration of flooding, depth to high water table and depth to bedrock as well a risk of steel and concrete corrosion. Each soil (map unit) is also rated for suitability of building site development for the following categories, shallow excavations, dwellings without basements, dwellings with basements, small commercial buildings, local roads and streets and lawns and landscaping. Suitability for the following recreational activities is also rated, camp areas, picnic areas, playgrounds, paths and trails and golf fairways.
A brief discussion of the criteria used for each rating is contained in each soil survey report. A more detailed discussion of the criteria used to rate each soil can be obtained by contacting the state office of the USDA-Natural Resources Conservation Service and speaking with the state soil scientist or a member of his staff. National guidelines for each rating are maintained and used in the preparation of each soil survey report but not widely published.
I have been using a product called XXX (septic system addative) for a few years. The problem is, they keep coming out with "a much improved" product. They claim that laundry detergents now have more antibiotics than before and they don't break down as easily. they also contain tricelan which causes buildup in the drain lines. I need to know if these products really work or am I flushing my money down the toilet?
(from M. Hoover) - I have not conducted research on this product. However, I had a student conduct a field research product on three other products and the short answer is that he did NOT measure any long-term statistically significant benefits of the additives (compared to the experimental control, eg no additive) during the duration of his one year study of 48 septic tanks. There were some short term benefits (for a month or two) for some of the parameters measured. We only looked at what happened in the septic tank itself and did not attempt to assess any potential effects in the drainfield. I am not aware of how the products he tested would be similar or different than this one. Please realize that this is only one study under one set of conditions for a few of the additives and is NOT a complete assessment of additives in general.
Whatever you decide regarding the additive, i suggest that you be sure to have the solids and scum levels checked in your tank to be sure they are not too great, or alternatively have it pumped regularly if those levels can not be easily measured by a professional on-site system service provider.
Hi. I just returned from a trip to (Louisiana, Montana, Michigan) and I noticed that the soil there was (red, black, brown, grey). Do plants grow better in a certain color of soil? What makes soils different colors?
(from S. Buol) - Most soils have three basic colors, gray, black and shades of red to yellow. Almost all the sand, silt and clay minerals in soil have a gray color. Organic matter is black. Most soils have black colors near the surface because of the additions of organic matter from the decomposition of leaves and dead grass. Red and yellow colors in the soil result from iron oxides that coat the gray mineral particles. Bright red colors result when the iron oxide mineral is hematite and more yellow colors result when the iron oxide mineral is goethite. Gray colors are present when neither organic matter nor iron oxide coats the mineral particles. This usually results in soils that are saturated with water for prolonged periods of time each year. When soils are saturated iron oxides become soluble and leach out of the soil leaving only the gray color of the minerals. A few soils in arid regions may have nearly white layers of calcium carbonate. It is seldom possible to infer the fertility of a soil from its color. Although organic matter rich, black colored soil is often an indicator of good fertility this can be misleading. Some black colored organic material may be too acid for good plant growth and/or lack quantities of nitrogen, phosphorus, potassium and other elements needed by growing plants.
I would like to get some information on peat pods and other above ground septic systems.
(from M. Hoover) - Here are a few websites and information sources that you night find valuable.
Here in the Soil Science Department at NC State University, we have a number of high quality professional training programs for field practitioners and for local decision-makers. You can go to our website (http://www.soil.ncsu.edu/) and click on Training, Short courses and Workshops to see the entire range of training programs. But I want to bring one of them to your immediate attention. The NC Soils and On-Site Wastewater Training Academy includes a series of training short courses identified as Soil Science at Work located at (http://www.soil.ncsu.edu/swetc/soilsacademy/soilsacad04.htm). There are a number of training programs in the Academy that will be useful to your needs. In particular I would suggest that you consider taking Tech 102: Technology Overview that introduces all of the new technologies at one of our five hands-on training centers located throughout the state. We just offered that course in Raleigh at our training center here, but it is still coming up at another training center (in Bolivia, NC).
I would particularly recommend that you take a course in the Academy called Tech 200: Septic System Options for Difficult Sites. That is only offered once this year, at Greensboro in early May. I have developed (for that course) a set of tables that summarize my experience finding solutions for difficult sites over the past 29 years. During the course we go through those options and how one would determine which one fits different situations. We also use small group settings to help the participants who come to the course find solutions to their difficult sites. We have even had consultants (and developers) come to the training, bringing their information about a proposed development and through the small group settings, helped them find options to increase the number of lots they can get form the land tract. You can attend the course without first taking Tech 102, but we won't be going to the field to actually look at the technologies in Tech 200, like we do in Tech 102.
Another training option I would suggest is our Subsurface System Operator Training School. It is a three-day short course that will be taught in Raleigh on August 12-14 this year. For more information about it, see our website (http://www.soil.ncsu.edu/swetc/subsurface/subsurf.htm). This school is intended primarily for people who will be operating the more advanced types of technologies, but has been useful for others who want an introduction to the technologies, since they are covered during the training.
The North Carolina On-Site Wastewater Section (OSWS) is the regulatory agency who deals with septic systems via the local health departments. The OSWS has all of the NC approvals for the new technologies on their website (http://www.deh.enr.state.nc.us/oww/). Look at the part of their website regarding experimental and innovative systems for the specific approvals of the newer technologies. Some require a site investigation by a licensed soil scientist to assure that the soil has adequate hydraulic capacity. The peat system you mentioned is just one type of advanced pretreatment system. It is a packed bed biofilter, there are also other similar pretreatment technologies now approved in the state for difficult sites. But in general some of these advanced pretreatment systems can be used in North Carolina with either a 25% or sometimes even a 50% reduction in
- the thickness of acceptable soil
- the horizontal separation (setback) to things such as rivers, lakes, etc, or
- the size of the drainfield area needed for the home or business.
Note that if the site and soil will support the reduction, an individual can only get a reduction in one of the three items above, not 2 of 3 or 3 of 3. That is if a reduction in thickness of acceptable soil is requested, you can't also get a reduction in horizontal separation or drainfield size.
There is also a new EPA Onsite Wastewater Treatment Systems Manual with a lot of information in it. You can get that on the web (http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm).
EPA also has a number of technology fact sheets (http://www.epa.gov/owm/mtb/decent/technology.htm).
A final excellent source of information is the National Small Flows Clearinghouse at West Virginia University. Their website (http://www.nesc.wvu.edu/nsfc/nsfc_septicnews.htm). I would like to get some information on peat pods and other above ground septic systems. They have a publication called Small Flows Quarterly that you should subscribe to as it is informative and free. You can call them at 800.624.8301 to get on their mailing list or even to ask technical questions and get answers to them.
I am interested in getting detailed information about what plants are acceptable (and not acceptable) to plant on or near septic systems and their leach fields. Any literature you might have or suggested books obtainable locally (Salisbury) would be appreciated.
(from M. Hoover) - First off, I suggest that you take a look at some newly updated Soils Facts publications on our website. They are:
Soil Facts: Septic Systems and Their Maintenance http://www.soil.ncsu.edu/publications/Soilfacts/AG-439-13/AG-439-13.pdf
and
Soil Facts: Septic Systems Owner's Guide http://www.soil.ncsu.edu/publications/Soilfacts/AG-439-22/AG-439-22.pdf
These are currently being printed and will be available soon in hard copy via your County Extension Center. The Owner's Guide is printed as a hard-stock file folder so that you can keep your septic system permit, facts sheets and other information about your septic system together in one place.
The plants that are of greatest concern are those that grow well under wet conditions, however any plant can potentially clog a septic system via growth of its roots. Here are some ways that can happen. Roots that grow into the septic tank itself can grow into the inlet pipe (the building sewer) coming from the house plumbing into the septic tank or into the outlet pipe that takes the liquid sewage effluent from the septic tank to the drainfield. If either of these pipes becomes even partially clogged, then sewage can back up into the house plumbing and possibly into the fixtures such as a toilet or shower. I have seen roots that get into a septic tank grow up into this building sewer and cause solids to build up in the pipe clogging it. The roots don't even have to fill up the pipe in this case, but just block the open flow of sewage (from the house plumbing system) into the septic tank.
On the other hand, roots from trees and other plants can grow into the gravel-filled trenches in the drainfield and actually clog the gravel itself as well as the distribution pipe that is installed into the gravel. When this happens, the sewage can either back up into the house plumbing or come out onto the ground surface resulting in a discharge of untreated sewage (a drainfield malfunction). It may seem amazing that tree roots can clog a three-feet wide gravel-filled trench that contains a four-inch diameter pipe, but I have seen it happen. The fine roots proliferate and fill in the open spaces between the stones as well as the distribution pipe. Most septic system installers are also familiar with these problems, having seen them during repairs of failing septic systems.
Generally, plants that grow well under very wet conditions are the major concerns. These include trees such as willows, elms, sweetgums and some maples. Your best source of specific information about types of plants that grow well in wet soil conditions is an extension agent at the local County Extension Center (there is a Center in every county). You can find the location of your Extension center (http://www.ces.ncsu.edu/). Ask them what types of plants survive under wet conditions in your locality. Once, you find out the types of plants that grow well in wet soil conditions, you should avoid planting these over top of or directly near either the septic tank itself or the septic system drainfield.
However, as mentioned earlier any plant can infrequently cause a problem. This is particularly the case in periods of extended drought when the septic system is the only source of subsurface water available for plant growth and the roots grow to it. However, this is usually not a major source of problems.