The Groundsman

January 2013

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the Groundsman January 2013 Like soil organic matter, compost contains a considerable amount of plant nutrients. A typical green compost material contains around one per cent nitrogen and the potential exists to use the material as a turf fertiliser if applied at a sufficient application rate. Although the nitrogen content is only slowly plant-available, it could provide a background source of nitrogen to the turf. Football trial at STRI In 2001, STRI set up a trial to investigate the potential for green waste and food waste composts to provide nutrients to perennial ryegrass football turf growing on a sandy loam soil. Would the accumulation of organic matter from the compost cause any problems with regard to the playing surface? Results obtained over two football playing seasons indicated the following: • The compost materials were applied at either 2, 5 or 10 litres per m2 (20, 50, 100 m3 per hectare) in July 2000 and October 2001. • The greatest impact on the depth of turf colour and ground cover was obtained from the food waste-derived material, particularly at the highest application rates. However, both compost treatments produced a greater tolerance to football wear compared to untreated turf. • Loose grass cuttings applied at the same application rates above produced similar results to the green waste compost. • There were no deleterious effects on the turf quality from application of the materials even although the highest rate of application (10 litres per m2) caused some smothering of the turf for a short period after application. Compost quality One major issue with regard to using compost as a fertiliser or soil/rootzone amendment is the fact that it can vary in quality. This will depend on the feedstock used to produce the compost as well as the process used to manufacture the material.The government-financed Waste and Resources Action Programme (WRAP) instigated a programme for providing a minimum standard for the production of a quality compost RESEARCH UPDATE 41 material.This has been developed to a British Standard, PAS100, which assures users that the material is consistent and contains little or no contaminants. During 2004 and 2005, STRI was commissioned by WRAP to carry out trials on the application of PAS100 grade compost to sports and amenity turf. This was carried out through a series of trials at STRI's trials ground along with external field trials supervised by Glendale Environmental. The aim was to assess the effect on turf quality from applying compost to football and golf fairway turf. The material tested was a green waste–derived product. The trial and main outcomes were: • Compost was applied at 6, 9 and 12 litres per m2. The material had been graded to less than 10 mm particle size. Three applications were made in 2005. • Comparison was made with the application of a controlled-release fertiliser product. • The results showed that the compost produced a significant quick release of nitrogen to the turf thus providing a quick green up; as well as the expected longer term release. • On football turf, wear tolerance was improved along with a reduction in surface hardness. • The most significant effect from the compost was obtained on a fescuedominated fairway turf where the compost application provided a significantly greater colour during summer drought conditions. This indicated that it was working as a surface mulch to prevent evaporation of soil water. • There were no deleterious effects on disease (dollar spot in fairway fescue was reduced from compost application) and no effect on worm casting. • The results indicated that the compost material (<10 mm size) should be applied at around 6 litres per m2 (60 m3 per ha). For football turf, the material can be applied during renovation with a second application in September. • For golf fairway turf the material (<10 mm size) should be applied at around 6 litres per m2 (60 m3 per ha) in March/April. It is particularly useful for areas prone to drought. Although spiking would help integrate the material this is not actually necessary and the material integrates with the soil surface naturally in two to three weeks. Compost pH One of the main concerns about green waste compost is its high pH value, which is normally around 8.4. However, the results of the trials above, along with other tests showed that this has little effect on soil pH. The liming effect of compost is, in fact, very small in comparison to liming materials and its potential to raise soil pH is low. Conclusions Most rootzone and topdressing manufacturers provide mixes with green waste compost materials as the organic component; usually at a rate of 10 per cent by volume. Thus compost is already being commonly used in turf management. The results of the STRI trials indicate that compost also can be used in a more intensive manner. It is most likely to be effective as a straight topdressing to weak turf areas especially if they are prone to drought with resultant poor turf growth and physically hard surface playing conditions. l About the author Dr David Lawson After graduating from Glasgow University, Edinburgh University and a two-year postdoctorate period at Oxford University, David joined STRI (Sports Turf Research Institute) in 1984. As research chemist, he has supervised the development of the STRI's Chemistry Laboratory, along with research activities in testing fertilisers and other products for use on turf. Research activities have now diversified into many other areas, including compost application to turf; engineered soil slope stabilisation; erosion prevention on footpaths; and the potential for bio-energy production from amenity grass. He is fully involved with educational activities at STRI and has developed a BASIS-approved FACTS course for amenity turf. David can be contacted by email for more details on the trials mentioned: david.lawson@stri.co.uk Visit www.iog.org for more information and digital editions

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