Solent Turf Supplies used the by-product of the anaerobic digestion (AD) process on 2000 sq m of turf over the last five months.
According to owner and managing director Robert Hack the results so far show that the turf area tested grew as well when sprayed with the AD digestate as the company’s usual chemical fertiliser. "Given its performance, and the fact that the digestate is 100 per cent organic, we believe that that a wide range of growers will place increasing value on this natural feedstock," he said.
The supply of the digestate has been made possible by micro power plant manufacturers SEaB Energy which is converting food scraps from the Best Western Chilworth Manor hotel and the Southampton Science Park, on which the power plant is located, into heat and energy.
While the electricity generated is being used to power buildings directly on the science park, the digestate, an end-product of the microbial process, can be used as an organic soil improver for turf growers.
The trials indicated the nutrient value of the PAS 110 compliant liquid digestate has an equal value to the applied chemical fertiliser normally used at the nursery. This was been backed up by scientific tests conducted at specialist chemical testing laboratory NRW.
The cost of the digestate is currently around the same as chemical fertilizers but, as more and more AD facilities come online, producers expect the price to fall.
Sandra Sassow, SEaB Energy’s CEO, commented, "As well as generating a reliable source of energy, these trials demonstrate that our micro-power plants also produce a completely organic digestate rich in nutrients. The lab tests and field trials have proven that it performs as well as traditional fertilisers, but without the chemicals and, over time, at a reduced cost. This presents plant and turf growers with a clear economic opportunity to shift to a more sustainable propagator as well as a potential valuable additional income stream for organic waste producers."
Government-sponsored organisation WRAP has also conducted research on the digestate at the Sports Turf Research Institute and at Cranfield University. The trials concluded that, when used as a feed for turf establishment and then as an on-going maintenance product, the effect of the digestate was comparable to fertiliser treatments and demonstrated clear signs of soil improvement.