If any gardeners are interested in having their soil tested, see message below from Dan Gill.


-----Original Message-----
From: Gill, Daniel J. [mailto:DGill@agcenter.lsu.edu]
Sent: Wednesday, February 15, 2006 10:41 AM
To: Kelly Alfortish
Subject: RE: Question about soil sampling in Lakeview

Kelly:
A basic soil test cost $7 these days (it was free a number of years ago). There is also a special Katrina soil test available that focuses on salts and sodium levels in the soil as these are particularly important when it comes to plants. I believe it is $4. He can contact the local LSU AgCenter Extension office for Orleans Parish which is now housed in Jefferson and request a kit for one or both of the tests. The number is 838-1170. I am also attaching an article the LSU Horticulture Department put together after we did testing shortly after the storm. It is especially important to remove and dispose of any sediment that covers the original soil. Although, this long after the storm I'm not sure how much is left. Let me know if you have any questions.
Dan Gill
LSU AgCenter


SOIL CONTAMINATION FROM HURRICANE KATRINA FLOODING MAY NOT BE AS SERIOUS AS FEARED

LSU Agricultural Center scientists and extension educators, concerned about damage to landscape, fruit and vegetable plants due to the flooding that followed Hurricane Katrina, collected soil and sediment samples from five areas in Jefferson and Orleans Parishes. Soil samples were taken in Kenner, Lake View, City Park, Mid-City and Old Metairie to provide information on the effects the floodwaters had on soil in various locations.

The LSU Agricultural Center team was mainly concerned about the salinity levels in the soil and how that might affect plants over the short and long term. Soil salinity is typically expressed as electrical conductivity of a solution extracted from the soil at water saturation, and is usually reported in millimhos per centimeter (mmhos/cm) or decisiemens per meter (dS/m). Preliminary findings indicate that the soil salinity in all areas is at or below levels acceptable for even low tolerance plants (less than 2 dS/m). Soil salinity values were slightly higher in the Mid-City and Lake View areas, but still generally should not cause problems (2 to 4 dS/m).

The levels of heavy metals, such as lead, arsenic, cadmium, nickel, zinc and mercury, were also of concern. The test results, however, found the levels of these materials in the soil samples were within normal soil levels.

The LSU AgCenter team also tested sediments that were deposited on top of the existing soil in areas covered by the brackish floodwaters from Lake Pontchartrain. In the Lake View area, these sediments were found to be high in salinity, up to 16 dS/m. However, heavy metal concentrations were found to be at or below average for most soils.

According to water samples analyzed by Dr. John Pardue and others at LSU to determine heavy metal levels in floodwater, lead, arsenic and, in some cases, chromium levels in floodwater exceeded drinking water standards. But with the exception of somewhat elevated lead concentrations in some areas, the levels found were comparable to what would be found in typical storm water runoff. So, what was exceptional about the floodwaters was not their level of pollutants, but that they covered such a large area and there was more extensive human exposure to the water. The incredible amount of water that flowed into the New Orleans area greatly diluted the pollutants it picked up. The team believes that this explains why heavy metal levels in the sediment are not greatly elevated.

Initial results, then, indicate that soil salinity and heavy metals should not be considered a problem in the areas tested. That means that there should be no problem with individuals digging or planting in the soil. Growing vegetables for consumption should not be affected by salinity or heavy metals in the areas tested. There is no need for special treatment of the soil before beginning to replant landscapes in areas that were flooded.

It is obvious that plants in the flooded areas were severely damaged or killed. In addition to studying soil samples, LSU AgCenter faculty examined landscape plants to answer the question of what happened to the plants that now appear partially or totally brown. They concluded that plants that appear damaged probably succumbed to problems caused by the floodwater itself, not pollutants in it.

The roots of typical landscape plants must have oxygen available to them. They get the oxygen they need from air spaces in the soil. When these spaces are filled with water, as during floods, roots are deprived of the oxygen they need. Roots will not function properly if they do not get oxygen. So the roots, which are solely responsible for absorbing the water a plant needs, quit absorbing water causing the plant to die (quite ironic that flooded plants died of thirst). The longer the soil stays saturated the more damage occurs.

Also, low growing plants were completely covered by the floodwater. And taller growing shrubs, such as Japanese yews, may appear brown where the floodwater covered them but green above that level. The extended period of time that the floodwaters persisted, combined with low oxygen and carbon dioxide availability in the floodwaters and low light reaching leaves submerged in the turbid water, would have killed the foliage that was below the water. So, low growing plants that died and larger shrubs that appear to have partial foliage death from the ground level to the highest water level were not affected by pollutants or salt in the water, but more likely suffered from lack of light reaching the leaves through murky floodwater and/or from a lack of oxygen available to their roots.

Shrubs that are brown only where the floodwater covered them will likely survive and recover. The brown areas may send out new foliage and, if that happens, the shrubs will look like they did before. If not, dead lower portions can be pruned away later once the homeowner can determine which portions of the plant are alive and which are not.
Trees that are totally brown or have leaves that appear to be turning brown probably suffered from low oxygen to their root systems. Magnolias seem to be especially hard hit. Only time will tell if these trees will recover from the extended flooded conditions. If there is any doubt, wait to remove these trees until next spring to be sure they are dead.

In areas where flood waters several feet deep covered lower growing plants for one or more weeks, it is likely that virtually all turf, herbaceous plants and most shrubs were killed due to reduced light reaching the foliage and root death due to saturated soil. However, any shrubs that are still green will likely survive. Carefully assess shrubs that may appear dead. Scrape the bark in several areas. Green tissue under the bark indicates the shrubs are still alive and may recover. Some shrubs that appear dead and leafless may begin to send out new growth a few weeks after the water recedes. Shrubs that show no green tissue below the bark when scratched and produce no signs of growth a few weeks after the waters recede, however, are likely dead. In the meantime, keep a watchful eye on these plants for any evidence of new growth.

Sediments deposited by lake waters were found to have high salt levels. Homeowners in those areas with a heavy accumulation of sediment should carefully remove the sediment from lawns and beds. The Environmental Protection Agency (EPA) has published analysis from sediment testing in most all areas that were flooded in New Orleans (www.epa.gov/katrina/index.html). Although levels of pollutants in the sediment do not appear to pose any serious health risk, the EPA recommends wearing proper protective equipment such as gloves and safety glasses when handling this sediment and washing with soap and water following exposure.

Based on these findings, there is not an overwhelming need for residents in flooded areas to have their soil tested. Individuals who would like to have their soil tested, however, may contact the LSU AgCenter Extension office in their parish.