Sub soiling and deep cultivations hit the headlines in Ukraine this year; well it would have done if I had written the headlines.
Spring this year was wetter than average which did nothing to encourage roots to grow deep looking for water. Added to this is the sub surface compaction that blights most of Ukraine and shallow, lazy rooted spring planted crops like soya and it becomes apparent why yields have been so low this drought year.
Would sub soiling have helped? 
The theory being that deep cultivations break up compaction allowing deeper root penetration and these plants are better able to withstand drought conditions than plants growing over compaction with a shallower developed root structure.
Is there any evidence to support this?
I have data on soya grown in central Ukraine over sub soil compacted soil achieving an abysmal 0.7MT/ha and not too far away on land that had been sub soiled achieving yields of 1.5MT/ha.
Some of this uplift might have been down to different agronomy or localised rainfall at key times but surely not all of it.
OK, so let’s assume it was down to better, deeper rooting which was achieved by sub soil and we want to subsoil for the next crop. Wisdom has it that you should sub soil in the summer on dry soils to get the maximum amount of shattering and cracking.
But if we want to plant in the spring we can’t do that so we need to sub soil in the spring when the land is wet and there is a danger of smearing with very little cracking and shattering.
Which eventually brings me to my point.
Assuming you could get a sub soiler in to frozen ground and you had the horses to pull it and assuming it didn’t break; would sub soiling in the winter have a similar effect to sub soiling dry soil in the summer and the frozen, brittle soil crack and shatter in a similar manner?
Anyone want to admit to trying it?