TURF FERTILISER.

Being sports turf consultants and turf agronomists we believe that providing the nutritional needs of turf grass is the cornerstone of turf management. The huge range of turf and lawn fertiliser technology that is now available has made this easier than ever before. This ranges from enhanced efficiency fertilisers to organic fertiliser to just your bog standard “straights’.

Just like the human body if you eat poorly you are going to become unhealthy, more susceptible to disease and not perform at your best. These principles apply whether you use a lawn fertiliser or are planning to fertilise turf on a major venue.

There are other less obvious benefits of getting your turf nutrition right:

• It is significantly cheaper than having to spray a fungicide. In a professional turf situation the figure seems to be a spray costs $1000/Ha. That’s without the labour and fuel costs factored in. There are very few fertilisers that cost that.
• Applying a lawn fertiliser is a lot safer than spraying turf chemicals.
• It increases your lawns water efficiency, due to a deeper, larger root network.
• Your lawn and turf areas will aesthetically look better.

As turf and lawn fertiliser suppliers we have a wide range of fertiliser technology to choose from. These range from mini prill lawn fertilisers ideal for use on golf greens and closely cut fine turf to fairway and sports ground fertilisers.

The following explains how nitrogen fertilizers work and where they should or shouldn’t be used.

If you need more information on other nutrients these blog articles will be of interest.

Magnesium turf fertilizers.

How to choose a good fertilizer.

Quick-release sports turf fertiliser.

Straight NPK’s:

‘Straight’ turf and lawn fertilisers are the low cost option. However, there is a reason for this. These tend to have a high salt index and can damage turf if not immediately watered in. They also cause growth surges that you have to mow the grass more often. For a golf course or Sportsground this may not be such an issue but if you use these as a lawn fertiliser it’s something that you should be aware of.

Water solubles:

These are of higher quality than ‘straights’. They are on the expensive side and are also prone to hardening or “caking”. To overcome this anti-caking agents are often used which can be abrasive to spray equipment.

However, an advantage of the water solubles is that they allow “spoon-feeding” of turf. This means a little and often can be applied so that turf grass is fed exactly what it needs and when it needs it. Bearing this in mind some manufacturers incorporate a low percentage of surfactant to increase the leaf uptake of any foliar turf or lawn fertiliser.

As a result of the above, enhanced efficiency fertilizers (EEF) have become popular. This is due to a several factors:

• Firstly, their increased safety. There is less chance of damage to turf;
• Secondly, they last longer;
• They are less prone to leaching into waterways and finally
• There is no big surge in growth which needs more mowing.

Enhanced Efficiency sports turf fertiliser (EEFs).

EEF‘s limit nutrient losses and so improve nutrient use efficiency. You can divide this fertiliser technology into two groups: Slow-release turf and lawn fertilisers and nitrification and urease inhibitors.

Slow-release sports turf fertiliser.

IBDU and urea-formaldehyde turf fertilisers come under this heading. For more information check out Slow-release fertilizers or our blog on How slow-release fertilizers work.  

The main advantages of slow-release fertiliser technology are:

• They are very safe to use as they have a low salt index. This means that they are less likely to burn and you can apply and forget;
• Secondly, they don’t leach like “straights”;
• Thirdly, as you apply these less often, it means a big reduction in labour costs;
• They reduce greenhouse gases by minimising nitrification and volatilisation;
• You don’t get massive growth surges and
• Lastly, there they don’t cause lush disease-prone growth, unlike straight fertilisers.

Table showing commonly used Enhanced Efficiency sports turf fertilizer (EEFs).

Polymer sulphur coated urea (PCSCU):

This fertiliser technology has nitrogen contents of 38–42%, 11–15% sulphur, and less than 2% polymer. Sulphur coated products have become popular sports turf and lawn fertilisers for several reasons:

• Firstly, they have a high nitrogen content of around 30–40%;
• Secondly, they reduce leaching and volatilization;
• Thirdly, sulphur is relatively cheap;
• Lastly, sulphur is itself a valuable secondary nutrient.

However, the main reason these have come to dominate the Australian market for lawn fertilisers is simply they are low cost and high analysis. I’d guess that over 80% of lawn fertilisers on the market that make the “slow release technology” claim are either based on SCU or PCSCU. Whether this the best slow release fertiliser is highly debatable due to the variety of alternatives on the market but even between the PCSCU products there is a massive variation in quality.

Problems with PCSCU fertiliser technology

Problems can develop if the coating cracks. If this happens, the fertiliser will just “dump” all its nitrogen. This is more common with the more brittle sulphur coated urea (SCU) compared to polymer sulphur coated urea (PCSCU).

In fact a batch of SCU granular turf fertilizer may contain more than 33% damaged granules and the rest be “perfectly coated” granules. This means that you then paying a premium price for a product which is 33% “up-front”. Long-term use of these can also result in increases in soil acidification due to their high sulphur content.

Lastly, the temperature has a crucial role to play in the release of PCSCU fertilizers. As temperature increases, their release rate increases. This means that a turf or lawn fertiliser you apply in the spring will not and cannot last as long if you apply it in the summer. It also means that if the coating becomes damaged it can cause turf burning as it behaves like a “straight” fertiliser once this coating is damaged.

Image 1 (above). Some coated sports turf and lawn fertilisers claim to last for 12 weeks. This fertiliser technology releases all its nutrient in a matter of days if the prill becomes damaged. Despite many longevity claims, only polymer-coated urea gives the claimed release period.

Image 2 (below). A lower quality SCU prill that has dumped its N within 4 days of application.

Methylene urea and urea-formaldehyde sports turf fertiliser.

Ureaform contains around 38% nitrogen and is key fertiliser technology of lawn fertilisers marketed by Scotts. During its manufacture several ureaforms can be separated based on their solubility in cold and hot water. Depending on the release time, nitrogen availability can be divided into four segments based on the amounts of Cold Water Soluble Nitrogen (CWSN), Hot Water Soluble Nitrogen (HWSN), and Hot Water Insoluble Nitrogen (HWIN). At a temperature of 25°C, it is the CWSN fraction that turf uses.

The greater the percentage of hot water-soluble and insoluble nitrogen the longer the release. The long long-chain fractions release nitrogen over several weeks or months and the shorter chain fractions are available from a few days to several weeks.

IBDU.

This turf fertiliser technology releases independent of temperature. Temperature has a large impact on both urea-formaldehyde and natural organic products but little effect on IBDU.

Consequently, in cooler weather this provides good winter and early spring colour. Both the amount of moisture present and the particle size affect the amount of nitrogen released.

As the surface area increases, smaller particles hydrolyze more rapidly. There is a five-fold increase in N release after eight weeks when particle size decreases from 3–4 mm to 0.3–0.6 mm. In addition to this, IBDU-based fertilisers can ‘smear’ over the surface once they become wet which is an issue in areas such as golf greens.

In Australia, IBDU is available as a sports turf fertiliser as Floranid® (BASF). I’ve never understood why it hasn’t been promoted more into the home garden market for lawn fertilisers. Yes its expensive, but in areas like Victoria and the ACT it would be ideal over the late autumn and winter months.

Nitrification inhibitors as sports turf fertiliser.

The Nitrification inhibitor fertiliser technology, works by depressing Nitrosomonas bacteria in the soil. These microbes are responsible for converting ammonium to nitrite and nitrate in the soil. When soil temperatures are above 10°C, this usually takes two to four weeks.

By keeping the nitrogen in the ammonium form for longer, they subsequently slow down the denitrification process. Once you apply these they last from six to ten weeks. They do not kill soil microbes but instead slow them down. This fertiliser technology is found in turf and lawn fertilisers containing Didin or DMPP (Entec®).

Piadin® is an economical liquid nitrification inhibitor. You can use this with a “straight” turf or lawn fertiliser or as a standalone application to a turf surface. It doesn’t damage turf and has a high degree of flexibility with rates being 5-8L/Ha (50-80ml/100m2).

Research into the use of Nitrification inhibitors as turf fertilisers has shown that DCD is a better inhibitor for clay and loamy soils, while DMPP and Piadin® are better for sandy soils.

Urease inhibitors.

Sports turf and lawn fertilisers that contain Umaxx® or Uflexx® fertiliser technology contain both a nitrification and a urease inhibitor. To prevent volatilization losses, NBPT is combined with urea.

Urease inhibitors slow down the rate at which urea hydrolyses in the soil. This keeps nitrogen in a stable form for longer so slowing down the rate of urea hydrolyses in the soil. This in turn, reduces volatilization losses of ammonia to the air which in turn reduces greenhouse gas emissions being released into the atmosphere.

Be aware that there is no benefit from using these if rain or irrigation occurs immediately. So if your irrigating immediately after applying your fertilizer your paying for something you don’t need.

Dual Inhibited Alzon® neo-N sports turf fertilizer.

Alzon® Neo N is a dual inhibited nitrogen sports turf fertiliser and has a 46-0-0 analysis. It gives longevities of up to 10 weeks.

• It is very soluble;
• You can use this as a dry granule or by simply dissolve it in a spray tank. Rates are as low as 25Kg/Ha (250g/100m2);
• As this isn’t a coated fertiliser and instead the entire granule is impregnated, the inhibitors cannot be ‘rubbed’ off;
• Improvements in nitrogen efficiency, mean that you can reduce application rates with no detriment to turf growth;
• The you use this as a soluble it doesn’t leave any residues in the tank and lastly
• The nitrification inhibitor in Alzon^®neo-N reduces nitrate leaching by up to 50% which means it saves you money.

Liquids:

Liquid sports turf fertilisers give an instant turfgrass response. This is because of nutrients being immediately available and absorbed through the roots or leaves. Use these:

• When turf may not be growing at its maximum level such as in the middle of summer. This is when foliar uptake is efficient;
• Before warm-season turf dormancy and lastly
• If you want to avoid mower pick up on closely mown turf.

Their main drawback of liquid turf fertilisers is that they do not have any longevity, although as discussed below there are some slow-release liquid fertilizers.

Personally I believe in getting the best of both worlds by using a combination of liquid turf fertiliser and granular products. The results gained in combination are better than relying on one approach exclusively.

Slow-release Liquid sports turf fertiliser.

There are now several slow-release liquids on the market sold under a variety of trade names such as Fertech®, Sirflor®, and Nitrosert®. All of these have the following characteristics:

• Firstly, longevities of up to six to eight weeks;
• Secondly, low burn potential;
• Thirdly, a high tank degree of tank mix compatibility.

Slow-release liquid nitrogen can be applied as a spray application onto turfgrass and are also used as the nitrogen source in mixed NPK ;iquid fertilizers.

Organics:

Poultry manure and organic fertiliser manufactured from bio-waste are low-cost alternatives to synthetic sports turf fertilisers. However, organic fertiliser can have issues with odour and weed seed content.

As well as this, the salt index of organic fertiliser can be an issue. This is a result of bulking up broiler chickens with salt. As broiler chickens grow they are fed a high salt diet. This means that they drink more water and so put on weight faster. The end result is they get to market faster. This salt then passes into their droppings.

No matter what the marketing says if there are claims about only using free range manure in their organic fertiliser product these are highly debatable. I personally doubt if all the free range poultry manure in Australia was used to manufacture organic fertiliser if it would meet the demand for these products.

Another major problem with organic fertiliser, is that it has a highly variable analysis. Due to their very nature, you can’t produce a consistent fertiliser analysis if you only use manure.

Organic fertiliser is characterised by having low nitrogen contents. These are usually below 3-5% and almost all of these also contain phosphorus. Their release is controlled by micro-organisms, which in turn are controlled by temperature and soil moisture.

Organic fertiliser like Dynamic Lifter®, Neutrog®, Terra firma®, and Queensland Organics® are all made from pelletised poultry manure. This is then either heat-treated using gas burners or composted to remove excess moisture. The amount of composting affects the amount of weed seed and the final moisture content which can vary from 8–16%.