Mark Hunt weather corner; 110
This summer has served as a timely reminder that two of the main consequences we face as a result of our changing climate industry concern irrigation and drainage.
It should also remind us of the fallacy that is long range weather forecasting beyond a couple of weeks; I can't remember reading anyone predicting our hottest June followed by one of our wettest July's, can you?
Our weather patterns (U.K & Ireland) are, as we know, strongly influenced by the behaviour of the jet stream and, in particular, its potential to form peak and trough patterns (image above left and right respectively) when it slows down periodically through the year. It is these jet stream patterns that bring us our most challenging weather conditions from a turf management perspective, and they can occur in any season of the year.
June and July graphically illustrated this phenomenon with a peak pattern staying in situ for 5 weeks and resulting in our hottest June ever as high pressure formed underneath. It also fixed the dominant wind direction for the same period. Come the end of June, a flip of the weather coin, and we end up sitting in a trough pattern, which allowed Atlantic low pressure after Atlantic low pressure to take their place in that trough and bring us cooler conditions and heavy rain (usually at the weekend!)
As I type this, I am sitting in my campervan on the cliffs of St Davids, Pembrokeshire, being buffeted by the howling wind and rain courtesy of Storm Betty and wondering if the awning is going to do a Mary Poppins (it didn't survive), and I can vouch for that particular pattern continuing into August!
It could so easily have been the other way round, with 40°C+ temperatures this summer as southern Europe has experienced.
What does this mean for turf management?
It means we have to become more proficient at water management at both ends of the weather spectrum.
Images courtesy of meteoblue.com
The growing benefits of summer aeration
One of the biggest contributors to efficient water management, in my mind, is correctly targeted summer aeration. Removing and/or diluting surface organic matter ticks the twin boxes of increased water infiltration and the encouragement of a better root system to allow the grass plant to ride out those temperature extremes. We also get gaseous exchange as another benefit, a must during prolonged rainfall and the associated development of anaerobic (oxygen deficient) soils. Decompacting with a narrow tine vertidrain joins the dots between surface and deeper profile aeration and is minimally invasive to boot.
Aeration in that critical window of mid-August to mid-September is also about the potential to get fast recovery, so surfaces return to optimum in the shortest possible timeframe.
The image above features a snippet from our Prodata reporting software (for August-to-date) from a site near Thame, Oxford.
Just look at the daily Growth Potential; it has been sitting on or close to optimum since early August and will likely remain so until mid-September, so recovery from aeration at this time of year is usually rapid.
Far from being an inconvenience, I would argue that summer aeration is nowadays a necessity to allow us to cope with the climatic extremes a topsy-turvy jet stream throws at us.
One last point relating to the above stats for August. I have highlighted the Smith Kerns Dollar Spot Probability figures, they are all > 25% peaking at > 40% mid-month. That means great conditions for fungal disease development,
another consequence of a cool, wet summer and explains why Dollar Spot, Microdochium nivale, Red Thread, Anthracnose and Take All have all been prevalent of late. The good news is that any turf damage from these pathogens can be quickly rectified with good grass growth conditions and optimum soil temperature for seed germination.
There's never a dull moment in turf management!
Mark is well respected in the turfcare community and welcomes your questions. Send them to: editor@pitchcare.com