SUSPHOS: Sustainable phosphorus (P) fertilization on golf courses


Photo: Anne Falk Øgaard, NIBIO, is responsible for the pot trials studying P uptake at various temperatures. 

Phosphorus (P) causes eutrophication and is the plant nutrient with the most limited global reserves. The turfgrass SLAN (‘Sufficiency Level of Available Nutrients’) recommenda-tion to maintain soil P levels at >54 mg P/kg (Mehlich 3) has been challenged by MLSN (‘Minimum Level of Sustainable Nutrition’) suggesting a critical soil level of only 21 mg P/kg. MLSN usually means lower P inputs than the STERF recommendation for precision fertilisation (PF), in which P is given at a constant ratio to nitrogen (P/N = 0.12) irrespec-tive of soil level. However, the PF recommendations were developed for established turf and have not been verified for turfgrass establishment from seed.    

This projects compares P-inputs according to PF, MLSN and SLAN on sand-based greens. Work-package (WP)1  focuses on turfgrass grow-in, i.e. the developmental phase usually considered to require most P, especially at low soil temperature. In spring 2017 and 2018, turfgrass coverage, clipping yields, root development and P uptake at constant N but increa-sing P rates were studied over a 7-8 wk period after sowing creeping bentgrass in cylinders filled with silica sand (pH:5.3;  Mehlich 3: 12 mg P/kg,) in phytotrones at 7, 12 and 17°C.      

While control cylinders without P fell significantly behind, turfgrass coverage did not re-spond to a higher P/N ratio than the PF norm of 0.12 at any temperature. In contrast, there was a trend for clipping yields to increase up to P/N=0.24 (Figure 1). This was confirmed by leaf analyses showing above-ground dry matter production to be P-limited if the P/N ratio in input fertiliser was <0.18. Turfgrass top/root ratio always increased with higher P/N ratio. WP2 is also conducted in phytotrons at 7, 12 and 17 °C in April and May and compares increasing inputs of foliar or granular P for faster green-up of established creeping bentgrass turf in spring.  One more round of this trial will be conducted in 2019, but results to date show no benefit of either foliar or granular P on a sand with Mehlich 3 = 44 mg P/kg.    

In WP3, field trials comparing  zero P vs. P inputs according to SLAN, MLSN and PF models on golf courses in China, Netherlands, Sweden and Norway were accompanied by one new trial established in May 2018 at Dütetal GC, Germany. Observations from some of these trials show certain trends, e.g. better recovery in spring and more Poa annua with increasing P input. Observations will continue for two more years, and it is too early to conclude.


Project background:

Phosphorus (P)
results in eutrophication of freshwater and is the plant nutrient for which global reserves are most limited. Many countries have lowered fertilizer guidelines for P in agriculture, but not for turf. STERF’s Precision Fertilization recommends P inputs at a constant ratio of 12 % relative to nitrogen, but this seems redundant for many soil types. The objective of this project is to generate knowledge on how fertilizer costs and environmental impact can be reduced by adjusting P fertilization to soil P according to ‘Minimum Levels of Sustainable Nutrition (MLSN)’ (Woods et al. 2016). In the  study, the need for more P at low temperature and during turfgrass (re)establishment is tested in greenhouse trials, while the MLSN guideline for P is tested on golf greens in Europe and China. Results are spread through STERF, GEO and FEGGA.

Fosfor (P) er en kilde til forurensning av ferskvann og samtidig det plantenæringsstoff der verdens reserver er mest begrenset. Mange land har redusert gjødslingsnormene for P i landbruk, men ikke for gress til grøntanlegg. STERFs gjødslingshåndbok tilrår gjødsling med 12 % P i forhold til N, men dette er trolig overflødig på mange golfbaner. Målet med dette prosjektet er å skaffe kunnskap om hvordan gjødslingskostnader og skadelige miljøvirkninger kan reduseres ved å tilpasse fosforgjødslinga til ‘Minimum Levels of Sustainable Nutrition (MLSN)’ (Woods et al. 2016). I prosjektet skal behovet for ekstra fosfor ved lav temperatur om våren og i forbindelse med (re)etablering av greener undersøkes i fytotron, og MLSNs grenseverdi for P skal etterprøves på golfgreener i Europa og Kina. Resultater vil bli kommunisert gjennom STERF, GEO and FEGGA.

Hållbar fosforgödsling på golfbanor

Fosfor är en källa till förorening av sjöar och hav och det är en begränsad naturresurs med risk att ta slut inom en nära framtid. I många länder finns stränga restriktioner när det gäller fosforgödsling. Det är därför viktigt att skapa optimala gödslingsstrategier för nordiska golfbanor dvs strategier för hur gödslingskostnader och negativ miljöpåverkan kan minimeras. I projektet medverkar forskare och praktiker från flera länder i Norden, övriga Europa och Asien. Projektet kommer att pågå under fyra år och genomförs vid NIBIO försöksstation i Norge med fältförsök på olika platser i världen.


Trygve S. Aamlid

Trygve S. Aamlid, NIBIO Division for Environment and Natural Resources, Turfgrass Research Group, Landvik, N-4886 Grimstad, Tel: + 47 90 52 83 78.

Category: Water, nutrients, construction
Status: Ongoing
Project period: 2017 - 2020

Fundings (kSEK)

  2017 2018 2019 2020 Total
STERF 525 551 452 458 1 986
 Other  149  149  149  145  593
 Total  674 700  601 603 2579


Principal objective:

Economic savings and lower environmental impact by reduced and more targeted fertilization with phosphorus (P) according to soil analyses.

Subgoals (corresponding to workpackages (WPs)):

  1. Determine the need for extra P fertilizer for turfgrass establishment or reestablishment on sand-based golf greens with low soil P values and at various temperatures (WP 1)
  2. Determine the effect on time of green-up and turfgrass quality of foliar or granular applications of increasing amounts of P at various soil temperatures in spring (WP 2)
  3. Document effects on turfgrass quality and fertilizer costs by switching form conventional SLAN-based fertilization to SPF or MLSN-based fertilization on golf course representing a range of climatic zones, soil types and turfgrass species.

Project participants

Trygve S. Aamlid

Head of Research

Norwegian Institute for Bioeconomy (NIBIO), Department for Urban Greening and Environmental Technology, Turfgrass Research Group, Landvik, Reddalsveien 215, 4886 Grimstad, Norway.

+47 90 52 83 78

+47 90528378

Send e-mail