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Hi All,

Rainbow290315Well a topsy-turvy weekend with mild temperatures, a howling wind and plenty of rain between short periods of sunshine. The only upside was that there were also plenty of Rainbows and I just never get tired of looking at them. No pot of gold under this one though 🙁

I’m afraid Easter isn’t looking that good now from a weather perspective as you’ll see below when I roll through the weather forecast, but with any luck it shouldn’t be a wet one, more cool, dry and settled I think for the most part, except Good Friday which is looking to be pretty wet for some….

The concerning factor weather-wise is that I still cannot see any really warm weather signal on the horizon on the longer-term forecasts (10 day) though the week after Easter should be milder in the south.

A quick shout 150329142722-rossi-wins-exlarge-169out for an icon of motorcycle racing – Valentino Rossi, if any of you caught MotoGP yesterday, I bet like me you were riveted to the sofa. A Grand Prix winner at 36 years old and a hell of a fighter, it proves age is just a number, not a state of mind !

 

General Weather Situation

Monday looks to start off dull and dry for most, except for a band of wintry showers affecting the north-west coast of Scotland. This low cloud will break during the morning to reveal some nice sunshine, but for Ireland we have a concentrated band of rain pushing into west Munster and Connacht by lunchtime and rapidly pushing east across all of Ireland during the afternoon. This rain will be into the west coast of England, Scotland and Wales by the evening rush hour and through the evening it’ll move across the rest of the U.K bringing rain to all. That wind will still be strong and gusty and from the west and temperatures will be into double figures for most areas.

Through into Tuesday and overnight that rain has cleared most areas though by the morning rush hour we will still have a mix of rain and sleet affecting the north-west coast of Scotland and England pushing inland into northern England. Further south and east, it’ll be brighter but cool with that rain staying on in the north west and over Ireland to give a day of sunshine and blustery showers. Some of these showers falling as sleet or even snow over higher ground and later in the afternoon they’ll push eastwards across the north Midlands into the east of England. The south should stay dry in the main and sunny. Temperatures will be similar to Monday, single figures in the showers and into double figures in the sunshine. That wind if anything will be even stronger on Tuesday with some really strong, intense gusts, so hang onto your hats.

For the 1st day of April we still have that band of wintry showers affecting the north-west, it’s a real feature of the week for them and an unwelcome one to boot. During the morning those showers will cross east and push down into The Midlands, but again the south and south-east looks to stay dry. For Ireland the rain showers look mainly to affect the north-west coastline, Donegal and the like, but further south the chance of showers early on reduces so maybe a better start to the day for you on Wednesday. As we progress through Wednesday however, those showers sink south into Munster, Connacht and Leinster and for the U.K they slip down into North Wales and northern England / The North Midlands. Temperatures will be cooler on Wednesday, high single figures only, still with that westerly wind, but it’ll be declining in strength a little from Tuesday blasts, still strong though.

Into Thursday and that showery slant to the weather is still with us, with rain set in a band over Ireland and the south-west / south coast of England and Wales. It’s role reversal for Thursday because that rain is set to stay over Ireland and the southern half of the U.K with Scotland and the north of England looking largely dry, if a little on the dull side. One thing we will lose is that wind, calming down to light to moderate, but shifting a little to the north west so keeping the temperatures down.

For Good Friday we have a band of rain moving in overnight into Ireland and that progresses into the U.K by early morning. The band will orientate itself straight down the middle of the U.K from Scotland to the south coast and at present it looks like everyone save the far east of the U.K will be sitting under it. By the afternoon it looks to have cleared Ireland thankfully but elsewhere it will remain in situ for the whole day, so if you’re under the worst of it, they’ll be some appreciable rainfall totals. Definitely going to be a Good Friday where you do inside jobs 🙁 Temperatures will remain cool and the wind will swing all the way round to the east to become moderate in strength. Again some of those rain showers will fall as sleet or even snow over the high ground of Wales in particular.

Looking at the Easter break we have a much drier theme after Friday’s deluge you’ll be pleased to hear and although it will be on the cool side there will be some good spells of sunshine, particularly over Ireland, Wales and England. Scotland looks to have more in the way of cloud cover, particularly for the 2nd part of Easter, but it’ll be dry here as well. High pressure looks to be in charge for Easter so not a total disaster. They’ll be a chance of ground frost through the weekend to start the day but temperatures should be just into double figures in light northerly / north-westerly winds. For Easter Monday we have a new low dropping down and that may bring stronger westerly winds and rain to the northern tip of Scotland.

Weather Outlook

A tricky forecast to predict after Easter as we have a low pressure pushing down to affect the north of England, Ireland and Scotland on Tuesday, so that means mild, westerly winds and rain. Further south it looks more settled, light winds and maybe warm in them as well with temperatures pushing up a little as we go through the week. As we close out next week the outlook becomes more unsettled and so I expect a return to cooler, sunshine and showers.

Agronomic Notes

GDD – Where are we now ?

Continuing my theme of charting GDD  data this spring, we can see that (as predicted by Meteoturf) we did indeed get a nice lift in GDD over the weekend with the milder night temperatures playing a big part in this process.

GDD290315

That lift drags our cumulative total for the year up a bit, but we are still tracking 24days behind 2014 in terms of growth.

GDDCum2903145

 Why do I use 6°C as a base temperature and other GDD models use 0°C ?

A number of people have asked me why I chose 6°C as the base temperature for my GDD model when I started out down this road 3 years ago ? In the U.S they use 0°C for their PGR models. The answer is that I think 6°C is the temperature when you start to see growth of the grass plant so if we have a day where the GDD is positive using this base temperature I think it correlates with actual growth. Now compare that to the GDD models that they use in the U.S, where for example they apply Trinexapac-ethyl every 200 GDD calculated with a 0°C base.

If you applied the U.S GDD model to this spring, you’d have already applied PGR on the 22nd February and the 26th March, Why would you do this when most end-users are reporting to me that they have barely cut greens-height turf this year and outfield turf has only shown a small amount of growth in early January and for a few days in March ? I think the 6°C GDD model correlates well with that and the 0°C doesn’t.  It is not always sensible to translate everything Stateside to the U.K and Ireland and think that it’ll work.

Plant Nutrition

I’m hoping that a lot of you took the opportunity to take advantage of the growth window forecast by Meteoturf last weekend and applied a granular fertiliser (if you needed recovery) If you didn’t and your turf surfaces need a pick me up before Easter, it’s going to be tricky this week because of the strength of the wind. You may get a chance to apply on Thursday but be mindful of Friday’s rainfall forecast. That’s why I said last week you have to seize the opportunities when they present themselves, easy for me to say when I’m sitting in my office I know, but harder to do for you guys sometimes. So in my mind we are still in a granular spell of weather if you are looking to apply some nutrition to your turf.

Looking ahead on Meteoturf, the growth forecast shows a declining trend with a small amount of response forecast this week due to the dropping day and night temperatures.

GDD290315

You can also see rainfall forecast for the end of the week, particularly on Friday 🙁

Wetter surfaces this winter and the penetrant debate

A lot of people have commented to me that in general their turf surfaces were wetter this winter and in some cases grass cover has been lost because of it. Why should this be when the rainfall up until mid-January 2015 was on a par with last year if you look at it from a total perspective ?

Well, firstly as I pointed out earlier this year in my blogs, rainfall totals are deceptive and it is rainfall patterns you should actually be looking at. In the autumn / winter of 2013 we had a 3- week dry spell from the beginning of November to early December and although it followed a very wet October (like 2014), surfaces and rootzones did dry out. In the autumn / winter of 2014 this was not the case as a wet October was followed by a wet November and a wet December, so surfaces never got a chance to dry out. That’s the first reason surfaces were wetter in general this past autumn / winter.

The reason grass cover was lost was down to hypoxia (lack of oxygen). When a rootzone becomes saturated it contains less oxygen because water is filling some of the pore space normally occupied by air. If this water-logging continues whilst temperatures are mild enough for the grass plant to continue growing (as they typically are in our mild autumn periods now)  the process of grass growth will further compound the problem. if you look at how a grass plant produces energy it breaks down carbohydrate molecules manufactured by photosynthesis, utilising oxygen as it does so and producing CO2 (Carbon Dioxide).

So if we have a rootzone that contains low soil oxygen because it is saturated with water and the grass plant continues growing, it will deplete the soil oxygen level and increase the soil carbon dioxide level. If uncorrected this leads to plant death. One of the first species to check out is Poa annua, the next is Ryegrass interestingly. (Note one of the most resilient is Bentgrass).

Rootzone schematic

Rootzone Schematic

So that’s why we lost grass cover on some surfaces over the winter because the rootzone is saturated, depleted in oxygen and potentially high in carbon dioxide and other toxic substances.

Would an application of a penetrant change this ?

Well no, (IMHO) because the reason that the rootzone is saturated is down to soil physics with either L1, L2, L3 and / or L4 not functioning correctly in terms of water movement. Applying a penetrant wetting agent with whatever claims are made on the label (and let’s face it, they are many and varied and often entirely unsubstantiated by trial data) won’t achieve ‘Diddly Squat’, if the rootzone is compromised physically.

If we look at my very simplified schematic of a rootzone above we can see we have a number of potential barriers to water movement.

The first is L1 – Here we have a layer typically high in organic matter and this one is where your topdressing practices have the most impact. If you apply sufficient topdressing this layer should feature organic matter and sand and this will be conducive to water movement. If you haven’t applied sufficient topdressing to ameliorate the organic matter, it will be tight in nature, compacted and very difficult for water (or anything) to move down through it into L2 and beyond.  A give -away is to cut a section across the profile and try to pull it apart, you’ll note it is very tight and often this is accompanied by bridged rooting as well if insufficient topdressing has been applied.

Assuming everything is fine and dandy with L1, we then have L2 and L3 to contend with. In my experience L2 tends to be pretty consistent with good levels of topdressing sand present mixed with organic matter to create what Dr. Beard calls a ‘Dirty Soil’. The exception to this is if past turf managers have used different dressings and / or if organic matter has been buried by topdressing on top of it past the point where aeration can remove it. You also see this sometimes on areas that have been turfed at some point in the past and the turf has brought in its own ‘unique’ soil and organic matter layer. In this instance you can have L2 acting as a barrier to water movement causing it to back water up into L1 and provide a wet surface, even if you’ve ticked all the boxes in terms of topdressing and surface aeration.

L3 to me is often the border between where topdressing runs out and native soil takes over. Of course in a USGA-Spec this is still sand, but in many ‘push up’ greens and sports pitches, this is native soil and more often than not clay. So we can easily have the same scenario with a non-functioning L3, as we have with a non-functioning L2, that is water perching above this layer, unable to move through it and eventually it will saturate L1 and L2, particularly during periods of prolonged rainfall.

In an ideal world L4 is a drainage layer, that is either a proper Herringbone drainage system or in some cases naturally sandy soil that allows water movement down into it. Another type of natural soil that is also very good in terms of drainage is limestone because it is naturally porous.

The above diagram and explanation is I accept a simplification, but hopefully you can see that simply trying to solve a dysfunctional soil issue by using a penetrant is not the answer. They will help for sure if your rootzone characteristics are conducive to water movement, but then again if they are already good in this area, you shouldn’t have a wet surface, should you ?

Ok that’s it for now, times up and a totally-saturated in tray beckons 🙁

I’m having some time off over Easter because I’m cream-crackered, so the blog may be later next week. In the meantime, all the best and a Happy Easter to all of you.

Mark Hunt