SPORTS TURF FERTILISER.

Being sports turf consultants we believe that getting turf nutrition right is the cornerstone to turf management. 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 to turfgrass. Besides this fertiliser has historically been a lot cheaper than using turf chemicals.

As sports turf fertiliser suppliers we have a wide range suitable for all your requirements whether they be greens, fairways or sportsgrounds. As a guide, 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 fertilizer.

Straight NPK’s:

‘Straight’ fertilizers are relatively low cost option. However, they generally have a high salt index and can damage turf if not immediately watered in. They also cause growth surges that will mean grass will need mowing more often.

Water solubles:

These are of higher quality than ‘straights’. Besides their cost, these 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 grass is fed exactly what it needs and when it needs it.

As a result of the above problems, enhanced efficiency fertilizers 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 and finally
• There is no big surge in growth needing more mowing.

Enhanced Efficiency sports turf fertilizer (EEFs).

EEF‘s improve nutrient use efficiency by minimizing nutrient losses. They are divided into two groups. Slow-release sports turf fertilizers and nitrification and urease inhibitors.

Slow-release sports turf fertilizer.

IBDU and urea-formaldehyde fertilizers 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 fertilizers are:

• They are very safe to use as they have a low salt index;
• Secondly, they tend not to leach;
• Thirdly, as they are applied less often it means a reduction in labour costs;
• They reduce waste by minimizing nitrification and volatilization;
• You don’t get massive growth surges and
• Lastly, there is no lush disease-prone growth.

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

Polymer sulphur coated urea (PCSCU):

All of these have nitrogen contents of 38–42%, 11–15% sulphur, and less than 2% polymer. Sulphur coated products have become popular sports turf fertilisers because:

• 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.

Problems can develop if the coating cracks as the fertilizer then will just “dump” all its nitrogen. This is likely 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 would be 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, the release rate increases.

Image 1 (above). Some coated sports turf fertilisers claim to last for 12 weeks. These release all their 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 fertilizer.

Ureaform contains around 38% nitrogen. 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. This is the science behind many MU and UF based sports turf fertilisers.

IBDU.

Temperature has a large impact on both urea-formaldehyde and natural organic products. However, it has 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).

Nitrification inhibitors as sports turf fertiliser.

Nitrification inhibitors for example Didin or DMPP (Entec®), work 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 applied they last from six to ten weeks. They do not kill soil microbes but instead slow them down.

Piadin® is an economical liquid nitrification inhibitor that is applied with a turf 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.

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.

The sports turf fertilisers Umaxx® and Uflexx® 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. 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;
• Can be used as a dry granule or by simply dissolving in a spray tank. Rates are as low as 25Kg/Ha;
• As this is not a coated fertiliser and instead the entire granule is impregnated, the inhibitors cannot be ‘rubbed’ off;
• Due to the improvements in nitrogen efficiency, application rates to be cut with no detriment to turf growth;
• No residues are left in the tank when used as a soluble 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 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 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 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 products manufactured from bio-waste are low-cost alternatives to synthetic sports turf fertilisers. However, they cannot have issues with odour and weed seed content. As well as that the salt index can be an issue as a result of bulking up broiler chickens. As the chickens grow they are fed a high salt diet. This means that they drink more water and so put on weight faster. This then passes into their droppings.

Another major problem, is that they have a highly variable analysis. Due to their very nature you cant produce a consistent analsysis fertilizer from manure alone. Organics are characterized 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.

Products such as Dynamic Lifter®, Neutrog®, Terra firma®, and Queensland Organics® are all made from pelletized poultry manure. This is then either heat-treated 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%.