Guide to fertilising on sports pitches, kindly shared via TurfCareShop.
In this blog we look at the what’s, when’s and how’s of fertilising on sports pitches from a Groundsman/Greenkeepers point of view, as l am not qualified to advise on fertilisers. These are just some of my thoughts and for product specific talk to your FACTS qualified sales rep.
Starting Point of a fertilising guide!
Something worth bearing in mind is fertilising ideally should be based on soil analysis test results, this testing is best carried out during the plant’s less active period of growth. Speak to your fertiliser sales rep, who should be about to point you in the right direction, in terms of creating a feeding plan.
Without soil nutrient test, we have no way of knowing what the soil has in the way of a reserves of Micro and Macro nutrients. If we have a very high level of Potassium, then why are we applying a feed with a high level of potassium included.
The great thing about having a test done, is as part of the testing process the soil’s pH level is also tested, this really is key as if the pH is off then the plant will not be able to take up the nutrients.
Nitrogen is so variable, so not included in soil nutrient analysis testing as a basic guide a 100% rye grass sward with removed clippings needs somewhere between 150-220 kg/ha, but very site and soil specific.
1 – Presentation – who does not like green and stripy grass? Often players view a pitch based on how it looks, before they even play on it!
2 – Replace lost nutrients removed during cutting (if boxing off), and nutrients leaching through the soil profile or taken up by the plant. The aim is to create the right balance of nutrients for the plant.
3 – Recovery from wear and tear (play) or foot traffic. Nitrogen (N) especially plays an important role in this as well as potassium (K).
4 – Encourages thickening of the plant through a process called tillering, if done as part of a regular cutting programme.
5 – Some fertilisers contain active ingredients, so as well as feeding the grass, it will also control weeds and moss.
6 – Prevention of turf disease, such as red thread which is a symptom of a hungry plant. Too much fertiliser (nitrogen) however, can also increase the risk of fusarium which is another disease associated with grass.
7 -Competition for space, grass will also move into spaces which will out compete other sources looking for gaps, i.e., weeds, moss and weed grasses (poa annua).
8 -Different nutrients bring something different to the plant’s basic needs.
a) -Nitrogen (N) for growth and recovery.
b) -Phosphorous (P) builds a strong root structure which is important around seeding periods.
c)- Potassium (K) important element for cell structure and wear and tear.
What’s does the plant require and when?
Again, the starting point ideally should be based on soil analysis results.
As a basic guide the bag will specify as there are different types of fertiliser, with some lasting for six weeks and some for nine months.
Conventional -granular- up to six weeks
Slow release – 2-6 months
WSF 2-4 weeks ideal for lower temperatures, when a quick uptake is required.
Liquid fertilisers (2-4 weeks)
What does N-P-K Mean?
Nitrogen, Phosphate and Potassium(K) are the leading macro nutrients required by the grass plant but there are also other macro and micro nutrients required by the plant and these include the below lists.
As a groundsman l am aware of the below macro and micro, but also rely on my annual soil testing results to identify any major shortages or excesses, other than that my main energy is on providing the plant with the required N, P, K.
What your soil needs will be based on a number of factors!
Clipping removal or not
Soil type, as sandy soils leach nutrients much quicker
Weather and the leaching of nutrients
Plant growth and clippings removal, will remove nutrients
Some grasses need more nutrients that others
Level of wear
The plants requirements
As a general guide (clay soil) the plant needs three times more nitrogen, than it does phosphorus and potassium. So, something like 220 kg/ha nitrogen, 70 KG/ha of phosphorus and potassium.
Every ground will differ, so there no set of numbers to work to.
It’s ok applying a simple 5:5:10 year-round, but if you have an excess of potassium already then you will make it worse, magnesium will be hard to come by for the plant and you will get yellow, droopy leaves and poor chlorophyll production…. the result being a sick plant. You would have been better off applying nothing at all! -Andy Mackay (ecb pitch consultant)
A clay soil holds on to nutrients in much higher numbers than a sand soil, but every ground and soil conditions differ and all the more so across the sports.
When should the majority of nutrients be applied?
Growth means removal of nutrients, so the highest demand and removal of nutrients is in spring/summer and autumn.
Everything should be based on soil nutrients analysis testing, but on a clay soil phosphorus holds onto well within the soil, so may only need applying during windows of seeding.
What do the numbers on the bag mean?
As an example, a 20 kgs bag of 5-10-10 contain 5% nitrogen, 10% Phosphorus and potassium. The rest of the bag i.e., is a carrier.
How much nitrogen have we actually applied, if using a 5-10-10 over 500 sqm?
35 grams a sqm x 500 sqm= 17.5 kg per hectare and for 500 sqm you are getting around 0.85 kg of nitrogen over the 500 sqm square.
So, the numbers on the bag are only a percentage of what nutrients are included in the bag, so that actually nutrients applied.
Signs the plant is in need of a feed?
The plant will slow in growth and become yellow in appearance and often red thread turf disease will creep in.
Ideally, we need to apply before the signs of yellowing, l like the ideal of feeding at half rates, but feeding every three weeks rather than the six-week stated on the bag. This kind of feeding can prevent peaks and troughs in growth.
How to apply fertilisers
What rates of application-The bag will always be king and l would always read the bag ensuring the application rate is displayed on it, with other details such as when to apply and when not too!
Application Techniques- Cricket Square
I have never got on with drop spreaders, so l prefer to use a cyclone spreader for the application of fertilisers.
If the spread of the fertiliser through the machine is 10ft wide, l will go over by 50% each pass, but remember l apply fertiliser at half rates
If still confused, then just go up the edge of the wicket and come down the middle of the wicket and work your way along the square.
Brian , with the assistance of Mark Wilton shop partner who will be guest host on next Wednesday TurfChat Q+A on all things fertilising.
To see a summary of a previous Q+A we did with Mark, take a look at this- https://turfcareblog.com/community-qa-on-fertilisers/