Article written by Henry Bechelet, ICL Technical Sales Manager.
The establishment of early spring growth is crucial for many types of turf. It may be needed to achieve recovery from winter disease, excessive wear or allow early spring preparation work to take place. A good early start to growth is at the forefront of many people’s minds at the moment, but which is the best fertilizer type to use?
ICL field trials over the years have repeatedly shown that if the soil temperatures are above 7 o C (and turf health is good) then early spring growth can be stimulated with the application of the right fertiliser. The trick is to choose the right formulation to encourage the onset of growth without any negative consequences (such as the accumulation of thatch or the development of disease). It is clear from our trials that it is weak and unfed turf that is most likely to get diseases such as Microdochium or leaf spot at this time.
The macro nutrition analysis of your early spring fertiliser might be influenced by the soil nutrient status but essentially the growth response will be driven by the application of nitrogen (and more specifically the sources of nitrogen and rate of application). There will only be a growth response from the application of phosphorus, potassium, calcium and magnesium if there is a genuine soil deficiency or if availability is in some way being restricted. The inclusion of sulphate of Iron is common in early spring fertiliser formulations because it promotes a quick colour response, it can discourage the development of moss and it can help slow down the rate of development of disease. The balance of nutrients is important, but the type of nitrogen is key for the most efficient response.
Our field work carried out in recent years during late winter/early spring shows that fertilisers containing sulphate of ammonia as their nitrogen source produce the best growth response at lower temperatures (above 7 o C). The turf will respond from the application of nitrate nitrogen but we find that it is less effective than sulphate of ammonia (which is why we don’t use nitrate in ICL granular fertilisers). The application of urea nitrogen will also give a good and immediate response. The response from organic sources of Nitrogen is slower(because it needs soil microbial conversion) and for this reason we think that they are not ideal if you need to generate a quick response at lower temperatures.
The rate of fertiliser application will also govern the level of response. Our aim at this time of year is to generate recovery without producing excessive levels of growth. For example, Greenmaster Pro-Lite “Invigorator Plus” 4-0-14 +8Fe applied at 30 g/m 2 (supplying a total of 12 kg of N/ha as sulphate of ammonia) will deliver 2-3 kgs of N/week over a 4-6 week period and will create a healthy growth response given suitable conditions.
On the other hand, Greenmaster Prolite “Cold Start” 11-5-5 +8Fe applied at 25 g/m 2 (supplying a total of 27.5 kg of N/ha as sulphate of ammonia and urea) will deliver 3-4kg of N/week over a 6-8 week period. So, the Cold Start will provide a greater initial response and continue to release over a longer period.
So, we all agree that being able to complete our early season greens preparation work as soon as possible would be ideal. There are a wide range of fertilisers to choose from at this time of year, just make sure you choose the ones that have been designed for the required response. We think that sulphate of ammonia-based feeds will give the most efficient response in early spring if you need to generate early recovery. Talk to one of our team of specialist FACTS and BASIS registered advisors if you need help deciding which would work best for you.