Trial of biodegradable mulch materials (Kent 2012)

Mulches are materials applied to the soil surface to control the growth of competitive weeds. The durability, practicality, and weed control efficacy of a range of mulch materials was tested for three years on a fertile ex-arable site planted with ash trees (Fraxinus excelsior (L.)) in southern England. Herbicides controlled weed growth effectively and resulted in the largest height and diameter increments for the lowest material cost. Biodegradable starch membrane mats, compressed wood fibre boards and hemp fibre mats did not control weed growth and did not improve height or stem diameter increment compared to the control. Hardboard and rubber mats both controlled weed growth and also significantly increased height and stem diameter increment. However, hardboard was difficult to handle on-site and rubber mats increased mortality, probably by reducing soil moisture availability. Costs of these treatments were high, partly due to small scale, experimental manufacture. Coir fibre mats with photodegradable membrane backing were durable, highly effective and practical. This was the only commercially available fully degradable material tested that resulted in a good growth response, comparable to that of non-biodegradable black plastic mats, which are often used on sites where herbicide use is not appropriate. On similar ex-agricultural sites, where a non-chemical approach is desirable, 1.2 m x 1.2 m coir mats with a photodegradable membrane are a practical alternative resulting in cost-effective growth benefits, although herbicides remain a cheaper, more effective option. See also: Stokes, V. (2012) Some biodegradable mulch materials provide effective weed control during establishment of ash (Fraxinus excelsior L.) on farm woodland sites. Quarterly Journal of Forestry, 106 (4): 257-268. Attribution statement: