- High rainfall experienced throughout most of the UK this winter, with an additional dumping from Storm Henk in January, has left ground saturated and crops struggling. But what effect has this had on soil health?
Shane Brewer, from soil testing specialists Eurofins Agro UK, suggests that waterlogged crops or crops trapped under flood water for more than 15 days will almost certainly be lost. However, the longer-term damage to soil health can only be ascertained by testing regularly once the flood waters have subsided.
“Soil testing will identify the levels of bacteria, fungi and protozoa in the soil. Eurofins also offers suggestions for what can be put back into the soil which will improve the efficiency of fertiliser use and also help cultivation decision-making,” says Mr Brewer.
The roots of flooded plants stop taking up nutrients and methane is produced in the soil instead of carbon dioxide. Ethylene also builds up in the plant roots which will subsequently affect the way any new seeds germinate.
“Should a farm choose to abandon a winter crop and sow a spring crop, a soil test will be vital to understanding how that crop will need to be treated,” adds Mr Brewer.
Microbial populations decline when soils are flooded, and aerobic bacteria are replaced with anaerobic bacteria which produce gases like methane and nitrous oxide. The reduction in oxygen in the soil will also cause earthworm numbers to fall as they move on or die.
“Flooding washes away top soil that farmers have spent time and money improving. Topsoil contains the phosphorus, nitrogen and carbon that will help a new crop grow and, without it, farmers will need to understand what levels of inputs are needed to help soil recover,” says Mr Brewer.
Soil compaction is a growing concern, because, when hit by heavy rain, compacted soil lacks the air space to absorb water. This sees rain run off the land, taking top soil and nutrients with it.
“Deeper soil can absorb more rain, but in the UK we have large areas that have suffered years of compaction and lack the depth needed to cope with the sort of rain we have experienced this winter. To get the most out of compacted soil, testing will be required to help cultivation decisions such as whether to plough, if minimum tillage options are not deemed suitable,” concludes Mr Brewer.