Control of moss on reservoir dam embankments

Earth dam embankments need to maintain a year round high grass content sward to achieve a constant surface and ensure slope stability. Moss in the sward is considered to reduce potential stability, increase vulnerability to erosion and increase the risk of slips and trips. United Utilities and STRI have undertaken trials at Mitchell's House Reservoirs. The research objectives were to assess the degree of moss invasion, evaluate the optimum approach for controlling moss in sustainable ways, to identify optimum strategies of increasing grass dominance and to define practical safe and environmentally benign methods for delivery through basic grounds maintenance capabilities.

Moss control using several environmentally sensitive moss control products, physical removal by scarification and improving soil fertility to boost grass growth to outcompete moss, have all been successful strategies, with each treatment on its own significantly reducing moss content in treated plots. There was no advantage in combining the treatments. In terms of turf recovery, application of low levels of organic fertilisers and nitrogen were successful at speeding up the recovery of turf after moss removal, by scarification, resulting in almost full grass cover over all treated plots.