By Dr Andy Owen and Henry Bechelet, Technical Managers, ICL Turf and Landscape
The establishment of early spring growth is crucial, especially for golf greens. It is needed for the turf to recover from the damage of winter play and disease attack. Growth also allows us to proceed in earnest with surface preparation operations such as top dressing. A good early start to the year with the quick onset of growth would be the top of most greenkeepers Christmas list.
As Technical Managers it is our job to help you understand how to get the best results from our products. To this end we commission independent research studies and conduct our own trials to help us understand product performance and provide a solid grounding for our recommendations. In 2013 we commissioned a trial at STRI to help shed light on the subject of spring growth in golf greens. The trial evaluated a number of fertiliser alternatives and found that the one that created the best turf quality, best turf colour and got the LEAST disease was the analysis that very few people would use and certainly no agronomists would recommend! There is always plenty to learn. So, with this being such an interesting result we decided to set up a follow-up trial for early spring 2015 to see if we couldn’t shed some more light on this issue.
With the kind permission of Matt Houseman and the management team at Scarcroft Golf Club (just north of Leeds) we set up the 2015 Spring Fertiliser Trial on their chipping green. This is a relatively new green constructed upon a sand-based rootzone with the sward being predominantly browntop bent. It was agreed with Matt that the green would be maintained at the same intensity of the greens as a whole. At this time they were being mown at 6mm at regular intervals.
So, the plan was to apply various different types of fertilizer (conventional, slow release and immediate release) BUT with the application rates adjusted to deliver the same level of nitrogen. We wanted to see how nitrogen source rather than quantity influenced the onset of spring growth. The treatments were applied very early in the spring when conditions first allowed. The aim was to answer the questions…Do early spring fertilisers work? And…Does the type of fertiliser being used make a difference?
The treatments would be applied to plots situated within a randomized block design with 3 replications. Assessments were made at regular intervals looking at the visual aspects of turf colour and turf quality as well as measuring NDVI (turf vigour) and soil temperatures. The trial was set up in such a way to allow statistical analysis of the assessment results to make sure that our conclusions were trustworthy.
The treatments were as follows…
- Untreated control to show what happened without any fertiliser being applied.
- Greenmaster Prolite “Cold Start” 11-5-5 +8Fe. Contains “conventional” nitrogen sources with half of the N coming from sulphate of ammonia and half from urea to give a 6+ weeks delivery pattern. The perceived high nitrogen content is not generally regarded as being appropriate for an early spring starter in the UK. It also contains phosphate, potassium and a good whack of iron (8Fe). This was applied at a rate of 25 g/m2 to supply 27.5 kg of N per ha.
- Greenmaster Prolite “Turf Tonic” 8-0-0 +3MgO +3Fe. Also contains conventional nitrogen sources with roughly 60% of the N coming from sulphate of ammonia and 40% from urea to give a 6+ weeks consistent delivery. Contains no phosphate, potassium and less iron (3Fe). Applied at a rate of 35 g/m2 to supply 28 kg of N per ha.
- Greenmaster Prolite “Autumn Mg” 6-5-11 +3MgO +0.5Fe. Contains slow release and conventional nitrogen sources with 66% of the N coming from slow release methylene urea and the rest being mainly sulphate of ammonia with a little urea to give a 6+ weeks delivery pattern. Contains phosphate, potassium, magnesium but minimal iron. It was applied at a rate of 46 g/m2 to supply 27.6 kg of N per ha.
- Sierraform GT “K-STEP” 6-0-27 +2MgO +TE. Slow release and conventional nitrogen sources with 50% of the N coming from methylene urea and the rest being mainly urea with a little sulphate of ammonia to give a 6-8 weeks delivery pattern. Contains slow release potassium as well as magnesium and trace elements but no iron. Applied at a rate of 46 g/m2 to supply 27.6 kg of N per ha.
- Sportsmaster WSF “High K” 15-0-43 +0.13Fe. Quick release nitrogen sources with over 90% of the N coming from potassium nitrate with a little urea to give a 3-4 weeks delivery pattern. Contains potassium and a little Iron. Applied as a soluble feed at a rate of 18 g/m2 to supply 27 kg of N per ha.
So, you can see that we chose 5 very different fertilisers and these were applied at rates calculated to supply the same amount of N. There are quick, conventional and slow release forms of nitrogen being applied with varying amounts of phosphorus, potassium, iron and trace elements. These were applied on the 10th of March 2015 at the start of what turned out to be a cold spring. Take a moment now…what do you think happened?
DAY OF TREATMENT (10/03/2015): The trial was marked out and treated on the “first nice day of early spring”. It was the first opportunity to apply something to get things moving. Before treatment the plots were all scored visually for turf quality (1-9 scale), turf colour (1-9 scale) and NDVI. Each treatment went down well and all the treatments completely dispersed within a few of days after rainfall.
WEEK 1 (17/03/2015): The untreated plots were scored as being 5 for turf colour (acceptable) and 4 for turf quality (slightly thin but with acceptable colour). The most notable treatment reaction was the instant colour (6.5 – a good “hardened” green) brought by the “Cold Start” mainly as a result of the high iron content (+8Fe). The visual response from the other treatments was minimal in the first 7 days.
WEEK 2 (24/03/2015): The weather had remained cold (0oC at night 8-10oC during the day) but the daffodils were now out. Soil temperatures was at 9oC. At this time the untreated plots were deteriorating in terms of turf colour (4 - insipid) and turf quality (3 – weak and thin). The “Cold Start” plots were outstanding in terms turf colour (6.5) and turf quality (5) with improved density now being a real feature. At this time it was felt that the strong darkening (pigment?) effect of the high iron content had really helped get things moving with the “Cold Start”. The other treatments were clearly better than the untreated plots in terms of turf colour and quality but it was more that the treatments had prevented deterioration rather than promoting a positive response. The surprise was that the impact of the potassium nitrate wasn’t particularly strong and at no point were these plots any better that the conventional fertilisers based on sulphate of ammonia and urea.
WEEK 3 (31/03/2015): The cold weather persisted and the untreated plots continued to deteriorate in terms of the turf colour (3.5 - yellowing) and turf quality (2 – thinning badly). The “Cold Start” treated plots continued to be great in terms of colour (6.5) and quality (5). The other treatments were better than the untreated plots but the response was still not as strong as the “Cold Start”. The other treatments generally had a colour of around 4 and quality around 3. It was notable that the potassium nitrate was fading away now.
WEEK 4 (09/03/2015): It was now becoming a late spring with soil temperatures still around 9oC and the growth degree days being 50% of the average for this time. By this time the conventional “Turf Tonic” had caught up with the “Cold Start” in terms of turf colour (7) and turf quality (5). The slow release treatments were all better than the untreated plots but they hadn’t generated a strong response. The untreated plots had perked up slightly after a couple of warmer days but they were still poor and struggling badly.
The following photos were taken 23 days after treatment. The photo to the left shows that there was a huge difference in treatment responses whilst the photo to the right shows the response Cold Star was great.
So, after what might be considered to be an extremely early fertiliser treatment during what turned out to be a cold spring we got some really strong treatment effects. Without treatment the turf really struggled and deteriorated badly. Compared to the untreated plots all the early fertilisers worked well and prevented a deterioration in the turf quality.
Having said that, some of the fertilisers were markedly better than the others even though they had all applied the same amount of nitrogen. We would conclude that…
- The sulphate of ammonia and urea combination worked best and when this was combined with good high levels of iron the response was amazing.
- The slow-release fertilisers aren’t really designed to produce a strong response in early spring. Soil temperatures weren’t sufficiently high for the soil bacteria to convert and make available the methylene urea N sufficient to give a notable response. These are best applied when the soil system is functioning well
- The potassium nitrate was comparatively weak “pound for pound” in terms of immediate response and longevity.
The green was then top dressed and the differences in response became even more real. The “Cold Start” and the “Turf Tonic” treated plots really sailed up through the sand dressing while the others sat just beneath. We were really concerned just how much the top dressing knocked back the turf and we might need to rethink our advice on that also!
So, to conclude if this trial is anything to go by then the answer to our 2 questions is relatively straightforward…
Do early spring fertilisers work? Yes!
Does the type of fertiliser being used make a difference? Yes!
In this trial the Greenmaster Prolite “Cold Start” 11-5-5 +8Fe was the winner in terms of speed of response, longevity, turf colour and quality as indeed it had been in the 2013 STRI trial. The 11-5-5 formulation isn’t what people would generally use in early spring but remember that it can be applied evenly at 25 g/m2 to get great response from the iron and conventional N without overdoing it. For us Greenmaster Prolite “Cold Start” 11-5-5 +8Fe @ 25 g/m2 is how to get your greens going in the spring.