Home Buyers Will Pay for Soil, Won't Pay For Dirt

In 2003, the Snohomish County Public Works Department published a remarkable manual with a simple title: Building Soil (pdf). Promoting sediment-free stormwater, it encouraged builders to embrace the wisdom of retaining native soil and vegetation, and to question the value of turning soil into dirt for no good reason. From a building perspective, soil is a valuable construction material manufactured from a low cost/ low value soil resource feedstock. The thinking goes like this: Manipulating soil tidies up a site and adds value. Stormwater regulations interfere with the ability to add value, thus the disconnect.

Enter the Washington Organic Recycling Council which has a new site, www. buildingsoil.org, with a new and refreshingly non-regulatory spin for convincing builders to buy into the principles in the Building Soil manual. The pitch goes like this: Avoiding disturbance around the building footprint, in a sense, doing nothing, confers a marketable value on that soil resource.

New home buyers say they are happy to pay more for a healthy, easy to care for landscape – and that starts with the soil.

A timely message in a buyers' market.

Tallahassee waste water sprayfield nitrate concern for Wakulla springs

I have been following news on a 2600 acre sprayfield on the edge of Tallahassee, Florida. It is suspected of causing environmental problems 10 miles away in Wakulla Springs State Park and the Wakulla River. A recent 1000 Friends of Florida report (pdf) ties excessive hydrilla plant growth to nitrate from the sprayfield. The news this week is that the city, USGS and Florida DEP will be conducting dye tests to better understand how the groundwater beneath the sprayfield moves down gradient. I am reading the report. Striking is the relatively low (1.0 mg/l)nitrate-N needed to control the situation.

Image source: Tallahassee Democrat

Tech Tags: science farm irrigation soil edaphology eutrophication environment karst groundwater quality nitrate TMDL USGS government news

Product review - new vadose zone research tool moves to farm

Irrigated farm fields lose water to deep percolation. This groundwater recharge, and what it contains, is difficult to research. This is because sampling tools designed to intercept saturated flow tend to miss unsaturated flow. And visa versa. New technology extracts deep soil moisture using a wick rather than the active suction or gravity.

The first wick samplers were passive capillary samplers (PCS). This approach has now evolved into the current water flux meter (WFM) designed recently by Batelle soil scientist Glendon Gee. Two offspring WFM designs are commercially available: the Gee passive capillary sampler drain gauge (Decagon Devices, Pullman WA) and the vadose zone water flux meter (Sledge Sales Consulting, Dayton OR). In a recent journal article, the Decagon device is referred to as a capacitance water flux meter (C-WFM) and the Sledge device is referred to as a tipping-bucket water flux meter (T-WFM). The T-WFM is close to Glendon Gee's designs published in journal articles. The C-WFM was developed by Decagon soil scientist Gaylon Campbell in collaboration with Glendon Gee.

The original PCS devices needed a pit, best dug with a backhoe. Fiberglass wick length and strand size were calibrated to site specific conditions to prevent oversampling of unsaturated conditions. Today's WFMs can be placed in an auger hole or hand-dug pit. WFM configurations use a standard size and length wick which works for most situations. A recent journal article has an example of an oversampling problem.

There are strong similarities and distinct differences between the two firms. Like Decagon, Sledge maintains strong ties with Glendon Gee. Like Decagon, many of the 200 devices Sledge has produced have been for agricultural research. Compared to Decagon, Sledge is more a hands on, farm service and farm chemical oriented consulting business. With Wayne Sledge, the T-WFM is his flagship product. With Decagon, the C-WFM is a sensible addition, part of an extensive and well supported line of soil and agricultural measurement instrumentation. It appears that Decagon and Sledge have produced a similar number of devices and they are clearly on parallel tracks of success in refining their individual product.

Both firms have supplied most of their instruments to agricultural researchers, farms and clients concerned with water use efficiency and nitrogen use eficiency such as golf courses. There has also been environmental project placements, most often associated with landfill and mine-tailing closure

Decagon has put considerable effort into refining unit capacity to record water flux, less into water sample handling. The larger base of the Sledge unit enhances water sample handling options. Decagon has a stepped design which accommodates hand auguring the deepest portion, shortening installation time. Decagon has an extensive list of complementary devices and highly capable technical support staff. The Sledge unit is substantially lower in price. Choice is good.

Of particular interest in Washington State is wastewater spray field management. As mentioned in a government report: "The Department of Ecology has identified 20 spray field situations where wastewater was [improperly] applied [and conditions] ... led to contamination of groundwater...". This report was discussed here previously.

I spoke with Don Nichols, with Washington Department of Ecology's Water Quality Program, Eastern Regional Office, Spokane, WA. Don has encouraged the installation of WFMs for gathering vadose zone water quality information. Don referred me to Cascade Earth Sciences and Soil Test Farm Consultants for more information.

Dan Burgard, soil scientist with Cascade Earth Sciences (CES) in Spokane, WA has installed 7 Decagon C-WFMs in the Pasco, WA area, and 11 Sledge T-WFMs in southern California. CES modified the equipment to enhance sample collection capabilities. (See his photos below)

Dan Nelson, soil scientist with Soiltest Farm Consultants, Inc. in Moses Lake, WA has four Decagon C-WFMs installed in the Moses Lake, WA area. Both had nothing but good things to say about the potential uses of this type of data. Mass balance calculations will demonstrate if target water use efficiency and target nitrogen use efficiency is being achieved. Detailed daily data logs show exactly when percolation occurs. Percolation events observed to date are closely correlated with irrigation and precipitation events and even soil thawing events. As expected with the difference in weight between soil and the field capacity water portion, percolate nitrate and dissolved solids (salts) are several times higher than soil levels above the sample point. The devices are performing as intended.

One question I have is how many devices are needed to achieve statistical confidence in a mass balance calculation? Users independently tend toward sets of 3 units, with singles for spot comparison data. That is a sensible starting point but determining coefficient of variability on selected data would put the results into perspective.

None of the installations have been entirely glitch-free, mostly due to various data logger challenges or site specific soil related factors, such as coarse sands or depth limits. Users of the units are looking forward to continued refinements in data logger compatibility and would like to see costs come down and but give high marks for ease of installation and setup. This and available tech support make sampler units from Sledge and Decagon an attractive alternative to the do-it-yourself installations that predate this equipment.

References:
Brown, K.W., J.C. Thomas, and M.W. Holder. 1986. Development of a capillary wick unsaturated zone water sampler. Coop. Agreement CR812316-01-0. USEPA Environ. Monit. Syst. Lab., Las Vegas, NV.
Cary, J.W. 1968. An instrument for in situ measurements of soil moisture flow and suction. Soil Sci. Soc. Am. Proc. 32:3–5.
Gee, Glendon W., Zhang, Z. Fred, Ward, Andy L. 2003. A Modified Vadose Zone Fluxmeter with Solution Collection Capability Vadose Zone J 2003 2: 627-632 (highwire link) http://highwire.stanford.edu/
Knutson, J.H., and J.S. Selker. 1994. Unsaturated hydraulic conductivities of fiberglass wicks and designing capillary wick pore-water samplers. Soil Sci. Soc. Am. J. 58:721–729.
Selker, J.S., C.K. Keller, J.T. McCord. 1999. Vadose Zone Processes, Lewis Publishers, ISBN 0-87371-953-0, GB1197.7.S46 1999 [1] [2]
van der Velde, M., Green, S. R., Gee, G. W., Vanclooster, M., Clothier, B. E. Evaluation of Drainage from Passive Suction and Nonsuction Flux Meters in a Volcanic Clay Soil under Tropical Conditions Vadose Zone J 2005 4: 1201-1209 (DOI: 10.2136/vzj2005.0011) (highwire link)

Tech Tags: soil science physics edaphology drainage new technology design product review information government best management research water environment

Tetany animal health issue and soil, hay links

Tetany is a complex disease in that no specific condition triggers it in all cases. Gauge tetany risk using soil and tissue analysis when growing or feeding hay comprised solely of cool-season grasses. A grass-legume mix does not have this risk.

Tetany is a disease affecting ruminants and is associated with feeding or grazing bluegrass, bromegrass, fescue, orchardgrass, ryegrass, timothy and wheatgrass. It is caused by low blood levels of calcium and/or magnesium. Classic risk conditions occur when the forage grass is growing quickly in the spring and nitrogen levels are high. Less well known is that tetany can be a problem when hay is grown on soils with excessive soil potassium. Manure and potassium hydroxide cleansers are two potential sources. Lactating animals are more susceptible to tetany, thus dairies are particularly alert to the concern and tend to avoid growing or feeding grass hay exclusively. Forage guides may not mention it as a concern. A forage tissue ratio of K/(Ca+Mg) of more than 2.2 indicates a high risk of tetany and the need to supplement feed with magnesium (Mg) (see also). If an animal goes down and tetany is suspected, a veterinarian should be contacted for immediate treatment. Often an animal will recover if it can be given an injection of magnesium sulfate (Epsom salts) early on.

Preventative Mg feed supplement and the ready supply of alfalfa tends to keep the incidence of tetany to a minimum. My thought is that tetany is additionally controlled by the close knit nature of farm communities. Caring neighbors and long memories tend to interact sufficiently that tetany symptoms don't take more than an animal or two, usually the weakest anyway, before it is figured out. Perhaps this explains why analytical laboratories in my region are generally unaware of tetany or the role of soil and tissue nutrient levels. My opinion is that cooperative extension publications in the Pacific Northwest can do better in this area. Tips for preventing animal loss due to tetany should be included in the fertility guides published to help folk interpret forage test results.

See also:
Spring Mineral Considerations by Jeff Heldt (link added 03MAR06)
Controlling Grass Tetany in Livestock, by Cooperative Extension, New Mexico State University, available in pdf format

Tech Tags: soil science animal nutrition environment chemistry dairy manure farm waste recycling land treatment information