Recent mild temperatures and rain has melted snow cover across central and southern Russia and eastern Ukraine.
As temperatures returned to more seasonal averages this week the melt water, which had pooled and failed to drain through the frozen soil, turned to ice.
Several issues going on here that are worth noting.
Rain on snow is not a good thing, it speeds up thawing but it also collapses the structure reducing air spaces between ice crystals which is what gives snow its insulating property. A bit like very old loft insulation that has lost its integrity and is now half the thicknesses it was when it went in twenty years ago.
There is still plenty of snow on the ground but it is thin and less protective should temperatures drop further although more snow is forecast later this week.
Then there is ice which has the real capacity to do some damage.
Melt water and rain collected into low lying depressions and was unable to drain through frozen soil before temperatures dropped and it turned into ice.
Where snow has melted completely the ice is obvious but we also are finding ice when we dig through the snow.
Ice that has formed beneath the snow is, perversely, insulated from any rise in temperature and in all probability will be around now until the snow thaws sometime in March.
Ice has a high thermal conductivity and will amplify the effect of low temperature so it doesn’t have to get really cold to start doing some damage. It also has low gas permeability and, in extreme cases, will smother or suffocate plants by depriving them of oxygen (Poltarev et al., 1992).
Or to put it another way, plants in which are now encased in ice will start to die very soon.
It’s difficult to put the level of risk in to context given that much of the problem is hidden under snow and it is difficult to get out into fields at this time of the year but if pushed we are seeing issues on 10-20% of the fields we visited and across Moscow, Lipetsk, Oryol, Voronezh, Kursk and Belgorod.
At this time we don’t have verifiable information for Ukraine but based on what see near the Russian Ukraine border and anecdotal evidence suggest there is a similar issue in eastern Ukraine.
We won’t be able to fully assess the extent of any damage and yield implications until will carry out our independent Post-Winter Crop Tour of Russia and Ukraine scheduled for late March, subscription details to follow soon.
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