Soil Management After Hurricane Ida

Hurricanes harness enormous wind or water energy that uproots or shreds trees, destroys buildings and signs, erodes coastlines, and otherwise creates havoc on the landscape. Safety is the primary consideration following natural disasters.

This is a review of what we have learned in the past 20 years (16 post-Katrina) about managing soils after major weather events. Assessing and addressing soil related issues can begin after hurricane winds subside, the rain clouds move away, and the health and safety of humans or animals in our care is addressed. Human contact with water from hurricanes is best avoided as it potentially contains human or animal waste, and deleterious chemicals or other materials.

Hurricane water originates either from storm surge from the adjacent ocean, or from inland flooding from the copious rainfall. Surge water physically moves salt from the surface water onto the land. Conversely, rain clouds are formed from water evaporated from the surface; salts do not evaporate and remain in the originating water. Ocean spray resulting from wind action over the saltwater surface, or its physical movement by a tornado over water are two other physical salt movement pathways from water to land, yet inconsequential at the scale of hurricanes. Thus, surge flooded soils, rather than rainwater flooded, have potential salt problems that will affect plant growth.

A few weeks after Katrina altered Mississippi, Category 5 Rita produced a significant storm surge primarily in Louisiana and Texas. It overtopped some rice levees creating a sloshing bathtub affect, because it lacked the initial energy pushing it inbound needed to push it back out to sea, the salt water was held in the rice fields and created a residual salinity problem.

Given where Ida impacted Mississippi, salt issues in soils may arise in the same vicinity as Katrina: close to shore and in areas with few or no agronomic crops. Monitor growing plants, and test the soil for soil sodium, other available nutrients, and pH when it is sufficiently dry. If fields have sediment deposits, make sure that samples represent the soil mix that will exist after the deposited silt is mixed with the original soil.

Use soil test results to assess fertility because salt addition increases pH which influences plant nutrient availability. Remediation options are a case-by-case decision and are not very rapid. In some instances, leaching by using irrigation with low-salt water to move the salts down out of the rooting zone is sufficient. Adding soluble calcium prior to irrigation (gypsum is often used) will remove or exchange the sodium from the soil and will facilitate remediation.

Other soil issues arise inland where soils were saturated or flooded. When it is safe to enter agricultural fields, remove storm debris taking care to find and remove partly hidden objects that may injure animals or damage machinery. However, restrict heavy traffic on wet soils to avoid adding soil compaction to the management issues.