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Optimising nitrogen fertiliser use on turf


Fertiliser maintenance programs in public parkland tend to be driven by budgetary constraints rather than by plant needs. As a result, they can be ad hoc or virtually non-existent.

For turf, as with any grass, the main nutritional requirement is nitrogen (N). However, not all grasses are created equal when it comes to nitrogen. For example, blue couch will persist better than green couch under low soil nitrogen.

Experiments have determined the optimum nitrogen requirements for the maintenance of warm-season turfgrasses in Southeast Queensland.


Full titleEstablishment and management of salt-tolerant amenity grasses to reduce urban salinity effects (Nitrogen trials are a subsection of the broader project)
IDTU06006 (and earlier work TU02005)
DatesStart date: January 2007
End date: January 2010
Project leaderDr Rachel Poulter, (07) 3286 1488
  • To determine the optimum fertiliser nitrogen requirements for selected warm-season turfgrasses
  • To consider how and when nitrogen should be applied to maximise turf quality and minimise mowing
BenefitsThe project will assist in the development of nitrogen maintenance protocols for turf and parkland managers in Southeast Queensland.
MethodologyTurfgrass cultivars trialled at Redlands Research Station include:

Cynodon dactylon

  • Wintergreen and FLoraTeX™

Digitaria didactyla

  • AussiblueA

Paspalum vaginatum

  • Sea Isle 1A

Pennisetum clandestinum 

  • Male-sterile kikuyu

Stenotaphrum secundatum

  • Sir WalterA


There were six fertiliser N treatments (0, 50, 100, 200, 300 & 400 kg N/ha/year) applied as equal split applications in early September, November, January, March, and May. As well as taking dry matter yields every 2 weeks during the warmer months (4-weekly during winter), ratings were made of turf quality, density, colour, and weed content in each 2 x 2 m fertiliser plot.

ResultsThese results were collected from project TU02005. Nitrogen applications commenced January 2005 on an infertile forest soil.

  • A nitrogen shortfall is commonly experienced in spring, suggesting that rather than applying fertiliser N regularly in equal amounts during the growing season, it may be best to weight application towards the beginning of the growing season, with one or two larger initial dressings during spring followed by smaller amounts during the hotter, wetter summer months.
  • During the summer months, the grasses tend to run out of N within the two months leading up to the next split application, particularly if heavy rains have fallen.
  • The grasses responded differently to applications of nitrogen. This impacted on the composition of the grass sward. For example: high and medium fertility grasses dominated mixed swards where there was high available soil nitrogen and low fertility grasses dominated mixed swards with low available soil nitrogen.
  • Kikuyu has the highest fertility demand, needing around 300-400 kg N/ha/year for optimal growth and high quality use.
  • Optimal growth in the green couches studied was achieved at around 300 kg N/ha/year.
  • High nitrogen applications may increase the susceptibility of FLoraTeX™ to patch disease during early spring
  • Sir WalterA and Sea Isle 1A are medium fertility grasses, with optimum requirements of around 200 kg N/ha/year. Higher levels of nitrogen should be avoided, particularly during the hot summer-early autumn months, as the rapid growth this encourages also increases mowing requirements.
  • Sir WalterA maintains good density at lower N rates, but often lacks acceptable colour at those levels.
  • AussiblueA was the least nitrogen demanding, with optimum requirements of around 100-200 kg N/ha/year. AussiblueA resisted invasion by other grasses, even when no nitrogen was applied, but still responded to the highest rate of applied nitrogen (400 kg N/ha/year).
Project staffDr Rachel Poulter, Research Scientist
Bartley Bauer, Research Scientist
Matt Roche, Research Scientist
FundingHorticulture Australia Limited
Collaborating agenciesQueensland Primary Industries and Fisheries
Redland City Council
Gold Coast City Council
Research locationsRedlands Research Station


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