Results of various studies in the UK suggest that there are several advantages to more complex mixtures, including: 1) Greater resilience to variable conditions caused by extreme weather such as drought and flooding; 2) A reduction in overall weed biomass and suppression of both early and late weeds; 3) Opportunities for improving the synchrony between nitrogen release and demand due to mixing species with different lignin and phenolic profiles. The release of N can also be spread out over time due to mixing species with different decomposition rates, which can allow for a higher proportion of N to be taken up by the following crop; 4) Extended flowering / foraging period and resource availability for key insect pollinators; 5) Increased ground cover and an increase in yield which persists over time - generally achieving higher forage yields and potentially higher subsequent crop yields (an increase in ley biomass is likely to translate in to higher yields of a following winter cereal); 6) Improved soil structure (particularly through boosting soil organic matter); 7) Providing livestock with micronutrients necessary for good health and production; 8) Herbal ley seed mixtures are more costly than ryegrass/clover leys but this initial cost is balanced out by reductions in N fertiliser and protein expenditure and improved health in livestock and soil. The cost is also compensated for by the decrease of establishment failure risks, yield increase, and by the fact that leys can be self sufficient once established (requiring no additional N), and produce high protein forage for stock.