A nicer morning as I sit and type with the grey clouds banished for the time-being. Last Friday’s rain arrived across the U.K and Ireland and it was fascinating to see it move up from the continent. As you can see from the ATD Lightning Archive produced by the MetOffice and run on Netweather.tv’s website, the storms started in France and Belgium early Friday morning and then tracked northwards across the channel and into Kent.
That band of rain eventually settled in a line stretching from mid-Wales across The Midlands to the Wash and here in Market Harborough we were sitting right under it so we ended up with 25mm through the course of Friday and Saturday.
Nitrogen in the rain and the pH of rainwater….
I took a rain water sample as it was yakking it down on Friday night (neighbour’s curtains twitching at my antics) so it will be interesting to see how much N there was in the rain we received. I took some samples through April and May and you can see the variation in terms of pH and nitrogen contribution ;
The rain on the 29th April fell from some turbulent storms that came up from the continent whereas the rain over the 18th and 19th of May was from the south-west. It’s interesting to see the pH variation particularly when we expect rain to fall at around 6.5 – 6.7. That is because rainwater is actually a weak acid (carbonic acid in my college days, probably called something much more exciting now) formed from a weak association between carbon dioxide and water. The highest N contribution I’ve ever recorded was from rainwater collected during August 2008 in Dublin where we hit over 5kg of N per hectare per inch of rain falling during some torrential downpours. The N contribution is held to be a result of oxidation of atmospheric nitrogen dioxide (NO2) into nitrate N (NO3) by lightning and so we all get a nice dilute and free liquid feed 🙂
General Weather Situation
So starting the week we have a nice quiet day on Monday in terms of rainfall with only some light rain pushing across the Highlands and into the north east of Scotland during the morning. Elsewhere across Ireland and the remainder of the U.K we have a mix of high cloud and sunshine with that north east / easterly wind light to moderate through the day. Temperatures will range from mid-teens to a pleasant 20°C in the south of England if sunshine breaks through the cloud as it is expected to do later in the day.
Another single figure night going into Tuesday but you should start to feel the milder air as the wind changes round to the south west early on Tuesday. With high pressure safely in situ over Ireland and the central / southern half of the U.K, we will have a settled, warm day with temperatures pushing nicely up into the twenties. Further north as suggested last week, that low is reluctant to say goodbye so we will see a rain band crossing Scotland through Tuesday and pushing down into The Borders and Lakes through the course of the afternoon / evening, but even under the rain it will feel milder. There will also be some accompanying rain moving into Donegal and Northern Ireland through late evening.
Arriving at mid-week we have more in the way of cloud cover as rain pushes across Ireland and potentially some heavy stuff over the north west of England during the early hours of Wednesday. Further south it looks to be a duller day, but not a cool one after a very mild night compared to late allows temperatures to build into the low twenties through the course of the day. Those temperatures may even be higher during the afternoon if that cloud cover breaks.Winds will be light to moderate and from the west / north west.
Overnight into Thursday and another mild night as predicted last week incidentally and we have a weather map of two halves – east and west. Across the west we have a gloomy day for Ireland with lots of cloud cover and light rain through the course of the day I’m afraid. Further north we see some potentially heavy rain push in to the north west of Scotland later in the day on Thursday. South and east of this we have another bright, warm, sunny day for Thursday with similar temperatures to Wednesday. Across the south west of England, Wales and the west coast, the cloud will build through the morning and later in the day that may increase to give drizzle and light rain into Thursday evening. Some of that rain may be potentially heavy for the north of England and The Borders as well as Scotland later on Thursday evening / night.
Closing out the week that rain sinks south and brings more cloud cover and light rain to the north of England, north Midlands through the morning. Ireland and the west coast looks gloomy again I’m afraid with heavy cloud cover and a persistent risk of rain throughout Friday. Into Friday afternoon this rain fizzles out over the southern half of the U.K, but remains in place over Ireland. Scotland looks to have a drier day after the rainfall earlier in the week, but it will remain dull and some of that cloud may be thick enough for drizzle and light rain here p.m. It’s worth mentioning that there is a chance of heavier rain for the north east of Scotland through the latter part of Friday.This rain could track along the east coast overnight into Saturday but it’s a close run thing at present, one to keep an eye on really. As you’d expect there is wide temperature fluctuation across the U.K and Ireland with mid-teens only under that grey sky and light rain compared to low twenties in the far south of England during Friday. Winds will be light to moderate and westerly in orientation.
So how are we looking for the weekend ?
After the gloomy week it looks like Saturday should dawn bright and dry for Ireland and stay pretty clear through the course of the day. More in the way of cloud cover over the U.K, but there will be breaks in that cloud and we should be pretty dry for Saturday and Sunday, however that rain tracking down the north east coast on Friday night may just affect the east and south east on Saturday morning, tricky to predict at this stage. Temperature-wise we look to be mid to high teens on Saturday and higher on Sunday with more breaks in the cloud further south, so twenty degrees isn’t beyond the realm of expectation. Winds will be light and from the west / north-west.
Next week’s outlook looks a bit messy and tricky to predict with a real mix of weather systems and fronts, so I’m not 100% confident what I write now will transpire. The high pressure we have over the U.K looks to come under pressure (sorry for the pun:)) from a continental and a northern low pressure early in the week and this pushes it slowly out of the way meaning we have a more unsettled outlook for the start of next week. At present it looks like the south will be settled, whereas Ireland could get rain from Monday afternoon and into Tuesday. That rain will push eastwards to affect Scotland and the north of England, but the south may escape it. (sorry to the south east lads on that one) By mid-week, next week we have a big Atlantic low pressure system winding up to affect Ireland, the north of England and Scotland. Winds will be strong and from the south west here so some big waves for all you white horse warriors out there 🙂 The south will probably miss this system during Thursday so a settled week here, but I think it may sink south to affect the southern half of the U.K at the weekend. That’s a long way off and I hope I’m wrong as I’m off to The Goodwood Festival for the first time that weekend.
After the end of week rain (for some) and the accompanying high humidity, I’d expect a bit of Microdochium activity out there with the typical manifestation of summer copper blotches across the grass sward. Hopefully if your growth rate is acceptable then this shouldn’t require a fungicide application, particularly with the forecast for a more settled week for most people (Ireland and Scotland excluding that is)
Humidity = Patch Diseases so I’d also expect to see a good bit of Fairy Ring activity where that rain fell and also possibly some Waitea Patch because it’s a disease that loves moisture. Superficial Fairy Ring and Waitea look really similar with their regular yellow rings but despite the similarity, they’re actually quite different fungal families – the Superficial Fairy Ring is a Basidiomycetes, whereas Waitea is a Rhizoctonia. Looking at them on your turf surface, the difference is a lack of mushroom odour and little sign of organic matter depression if you push down on the yellow / affected area with the Waitea. (pronounced by me as “Wait here” :))
Management is very different though because whereas with the Superficial Fairy Ring you have to be careful of the rootzone becoming hydrophobic due to the action of the fungus (so hand watering and using wetting agent tablets is key). With Waitea it couldn’t be more different and so if you treated it like a Fairy Ring it would actually become more prevalent and that’s why it’s key to know what you’re dealing with. Waitea Patch loves moisture and so making sure your rootzone is properly managed irrigation-wise and running it on the drier side will decrease the severity of the symptoms. Yes you can treat it with a fungicide but I think with proper irrigation management you won’t need to.
Lots of these guys running around at present, on one monitored location their activity is about 1 week later than usual so although we’ve had a cooler spring it hasn’t affected them much in terms of life cycle. This one is I’m reliably informed a Welsh Chafer (Hoplia pilanthus) and it will now be out and about looking for a mate before breeding and laying eggs to start the cycle again shortly. (ho hum)
Nutrition and Plant Stress
As I intimated last week and MeteoTurf correctly predicted, the combination of warm temperatures and that ever present north-east wind gave us some high E.T’s at the back end of last week. Using data kindly supplied by Sean at The Oxfordshire, I charted out the air temperature, wind strength and hourly E.T and you can really see how the combination of high wind speed (+40km/h – 25mph) and high air temperature (23°C) ramp up the E.T loss from the grass plant. Once the temperature drops at night, the E.T loss drops off markedly as one would expect, even though the wind kept blowing throughout the night (albeit at a lesser strength), so temperature is the driver of E.T.
Evapotranspiration (E.T) isn’t just about moisture loss, we have to consider the physiological changes that take place in the grass plant during periods of high E.T, specifically the closing of the stomatal pores (to reduce evaporation of moisture from within the leaf) . Although scientific opinion is not totally clear how much role the stomatal pores play in nutrient absorption (some references say little), we know that when a plant is under high E.T stress, nutrient uptake is less efficient.
Looking at the above chart, if we’re applying a foliar feed early in the morning, say between 06.00 and 07.00 a.m, we can see E.T rates are low and uptake potential is likely to good. Every hour after this the E.T increases by 75% and by midday it is approaching the maximum level. What’s interesting is once it has reached this point it stays high right through till 18.00 p.m before beginning to decline again. So the moral of this story is if you’re going out with a foliar, the earlier the better is key, the same would no doubt apply to selective herbicide or fungicide uptake during the growing season.
You can see from a Meteoturf location in the south east of England (above) that we are going to be seeing some high daily E.T and high growth rates this week, the latter due to the higher night temperatures.
Food for thought (hopefully) if you’re planning on getting out with an application this week.
All the best.