Tips on Handling Waterlogged Soil Following Floods
It is very important to observe normal hygiene routines, such as washing hands, following activities in the wake of floods. Also, wear gloves, rubber boots and water-retardant clothes. Avoid direct skin contact with the sludge as far as possible and do not eat or drink during working on site.
Contamination with viruses, bacteria and parasites
Flooded areas and sludge deposits are contaminated with viruses, bacteria and parasites directly after the water has receded. The organisms in the soil and sunlight can destroy these pathogens. Flat tillage (every 2-3 weeks, 5-10 cm deep) helps air the soil and speeds up this process.
Contamination with mineral oils and fuel residues
Sometimes, flooded areas are contaminated with a thin oil film or sludge contaminated with oil. Even in this case, you can expect the soil to clean itself by autumn, although the tillage described above will also help speed up this process. Should the sludge or soil be suspected of being contaminated with mineral oil or fuel residues, a soil analysis can be carried out (Federal Environmental Agency).
"Nose test": to get a rough idea whether there could be an oil contamination, fill an air-tight container (e.g. jam jar) halfway up with soil/sludge and keep it sealed overnight. If there is no oil smell after opening the container, the soil will be mainly residue-free.
Contamination withe heavy metals
Local contamination with heavy metals may be possible in rare cases (flooding of urban areas, industrial estates, landfills etc.). A chemical analysis can be carried out, if in doubt (AGES, Dept. for Soil Health and Plant Nutrition).
Changes in soil properties
The release of larger quantities of sludge may change both the physical and chemical properties of the upper soil layer. Flat tillage (every 2-3 weeks, 5-10 cm deep) will help the soil recover. However, should the area be used for agricultural purposes next autumn or spring, an analysis of the upper soil layer (nutrient content, humus content, acidity levels, …) should be carried out (AGES, Dpt. for Soil Health and Plant Nutrition).
Use of flooded compost
The compost heap should be turned at least once or twice before putting it on the soil.
Use of vegetables and fruit
Vegetables and fruit that have come into contact with flood water should not be consumed. Additionally, you should not consume “ground” vegetables such as radishes, lettuce and kohlrabi that were in the flood and can be harvested 1-2 weeks later. Growing vegetable cultures that were under water and are ready to be harvested within a few weeks and months afterwards should be subject to a special hygiene routine before consumption. Vegetables and fruit that were under water can be made into compost or worked into the soil.
Usability of grass and green fodder
Grass or green fodder that was under water should not be fed or used as silage.