Soil PH levels questions with a industry leading expert
Welcome to the nomadgroundsman.com blog.In this edition we ask the genius of soil science Alex Vickers ,who is a technical turf consultant for the IOG, about some of the basics in regards to soil p.h,specifically in regards to cricket squares.
I hope you all now have got the seed in the ground but with the unseasonable wet period we have had ,you can be forgiven if you haven’t .If you haven’t don’t worry still time🌱
Alex, how does the pH affect the soil?
Well, that is the subject of a whole book – or at least several chapters. In respect to sports turf it only causes problems once it gets too acid or alkaline. So a pH below 5 and over 8.0 is likely to create issues with phosphorus uptake, especially if there is a lot of iron in the soil. A pH over 8 is normally caused by having a calcareous soil and though grass will be happy enough, if are using urea-based fertilisers you will lose a lot of the N you are applying through a process called volatalisation and the N is lost as ammonia. If this is the case for you, either on your square or outfield use a different type of N fertiliser. High pH can be caused by too much sodium in the soil but unless you are right by the sea this is very unlikely to be an issue. High sodium levels will de-structure clay soils to create poorly drained, massive soils which may compact well to get a hard, flat surface but will not support grass well and will not re-structure, so you will always struggle with grass growth. It is easily treated with gypsum applications but I have never seen it anywhere in the UK on a cricket ground so unless you get tidal flooding or sea water inundation it is not likely to be an issue.
If you have a square built from commercial cricket loam and top-dressed with that loam every year you are unlikely to have an issue with pH but it is worth getting it checked every 3 – 5 years or if your grass is struggling and it is not due to physical soil conditions, fertiliser regime or drought. Low pH can help discourage worms, which is helpful but again, if it gets too low you may have other issues with nutrition so keep an eye on it. At the higher end and lower end phosphorus may be an issue so if you are seeing signs of deficiency in the grass then use a foliar feed, check the pH and soil phosphorus levels and try to raise the pH with lime if too acid or with an acidifying fertiliser such as ammonium sulphate if too high – but lowering the pH of a calcareous clay soil is really a very slow process!
What is the optimum pH for a cricket square with a rye grass sward?
Anywhere between 5 and 8.0 will be OK but to aid worm management 5.5 – 6.5 will be helpful.
How can we test our own square?
You can get cheap pH meters and then make a soil slurry and test the pH that way. Use distilled water and use the same dilution every time you do it. Ideally a 1:5 dilution as a minimum, or a 1:7 as a maximum but it must be the same every time. Disperse the soil well by letting it stand for an hour after shaking vigorously then test. You can use litmus paper as well or universal indicator paper or solution or you can ask a friendly rep to test it for you! Even lab tests of pH are only accurate to + / -0.5 of a pH unit so don’t get too hung up on the exact result.
How do you raise or lower the pH and how quickly?
If you want to raise the pH then you will need to add lime and to know how much to add you should send off a few samples for a lime requirement test to a good laboratory. I use NRM Labs but there are lots of others to choose from. Response is pretty quick and you will see a difference the following year. You should then keep an eye on things as it may begin to acidify again, but normally clay soils hold their pH quite well as they are not prone to leaching but if there is a high natural sulphur level in your soil it may acidify rapidly again.
You can lower pH by using an acidifying fertiliser which over a few years will have an impact, but if your soil is very calcareous it may take a very long time. In drastic situations you could use an acid application but I cant think of a situation where this would be needed on a cricket square. Gypsum will aid in maintaining a pH around 7.00 but too much on a cricket square is likely to create really good structure, making it harder to compact your square so go easy on gypsum on your square – I would only use it if my square was saline.
What affects pH on a square?
The soil texture and composition are the key controlling factors as clay soils are chemically very reactive and are full of cations. To acidify such soils you would need to displace a lot of those cations with H+ and to do that would require either a source within the soil (such as sulphur or sulphide which as it oxidises creates a lot of protons) or a significant input from the environment, normally from rainfall. Rain is slightly acidic, being a very dilute for of carbonic acid, but if you are down wind of a brick works or other industrial source of nitrogen or sulphur it can get pretty acid and can over a long time have a measurable impact on soil pH. Generally though, in a well buffered clay soil change in pH is slow. If your soil is calcareous then within the soil itself is a lot of calcium carbonate which will maintain a raised pH almost regardless of what you do. It may be easiest to top dress with a commercial cricket loam if it worries you that much rather than try to acidify a naturally calcareous soil.
High levels of organic matter can also reduce pH as rain can dissolve some organic compounds within organic layers to create organic acids (humic and fulvic type acids) which then lower pH in the soil below. This is normally an issue where there is a deep thatch layer and a very permeable and poorly buffered soil, such as a sand dominated soil (sandy loam or coarser). But if you ever had so much organic matter on a clay loam square that is was impacting pH then you would not be playing cricket!! But it is another reason why thatch control is important and removing organic matter from the surface is an absolute must in cricket square management, though in playability terms the impact of thatch on play massively dominates the impact it has on pH.
As mentioned before if you are using an acidifying fertiliser such as ammonium sulphate then over time your pH will reduce and this may help control the impact of worms if you can get it at or below 6.5, but don’t go crazy. Additions of any kind of calcareous fertiliser such as calcified seaweed, lime, magnesium lime etc will all raise pH. If this is deliberate to raise pH then you must do it properly based on a lime requirement analysis. If you are putting it on for other reasons and did not think about the impact on pH then you may need to check your soil pH.
If you water heavily and you are in a hard water area then over time the pH of the soil may increase, but again, with a clay soil this is unlikely as when it rains excess Ca2+ will be displaced form exchange sites in the soil and leached out. But over the summer of 2018 it may have been an issue in very hard water areas if you watered every day. Check the pH of your water if you are worried. Even if it is very hard are you really going to fit an acid dosing unit ahead of watering? Or a water softening device? It may be just something you need to put up with but check your soil pH every few years and if you are concerned it is getting too high then use an acidifying fertiliser to reduce it to a level you are happier with.
Very cheap testing papers above,for only a few quid you can check your own soil ph levels .
A good time to try to raise pH is in autumn so any lime added can work into the soil, ideally just after spiking to work the lime down the holes if you can. You can check the pH anytime though, and if you are looking to acidify the square with your fertilisers then early spring is a good time to check, discuss it with your fertiliser supplier who can advise you on the best product to use and off you go!
I do think it is easy to get too worried about pH though, plants, even monocultures of ryegrass, can adapt and cope with a relatively wide range of pH in soils giving good swards and excellent pitches. If you do the cultural work well, get your fertilisation right and your thatch and organic matter control right you should not have too many issues with pH.The most likely issue that can be aided by changing pH slightly is worm activity but don’t go crazy on this and reduce pH so far that you end up with a load of other issues. Maybe just switch the surface, Rake and brush more often .
To do this month?
The below guide will be of help in this,but any specific questions post in the comments box below.
Next months blog!
Next month we are speaking to Alex Bennett of Notts Sport who will be giving us a insight into how to manage our non turf match pitches .