Commercial experience with Miscanthus crops: establishment, yields and environmental observations

This study investigates the commercial field conditions of miscanthus, growers issues, reasons for growing the crop and also the modelling of a realistic commercial yield. Juvenile and mature Miscanthus x giganteus of varying age are surveyed in growers’ fields across mid-England. We record in-field plant density counts and morphology of crops of different ages. Mature crops thrive on both clay and sandy soils. Plants surveyed appear robust to drought, weeds and disease, the only vulnerability is rhizome condition at planting. Mature miscanthus planted pre-2014 continues to develop, spreading into planting gaps and growing more tillers. In stands planted post-2014, improved planting techniques reduce planting gaps and create a reasonably consistent planting density of 12,500 plants ha-1. The main reason for growers' investment of miscanthus is not financial return, but relates to its low requirement for field operations, low maintenance cost and its regeneration. This makes a practical solution for difficult field access and social acceptability near public places (related to spray operations and crop vandalism). Wildlife is abundant in these fields, largely undisturbed except for harvest. This contributes to the greening of agriculture; fields are also used for gamebird cover and educational tours. This crop is solving practical problems for growers while improving the environment. Observed yield data indicates gradual yield increase with crop age, a yield plateau but no yield decrease since 2006. In stands with low planting densities, yields plateau after 9 years. Surveyed yield data is used to parameterize the MiscanFor bioenergy model. This produces options to simulate either juvenile yields or a yield for a landscape containing different aged crops. For mature English crop yields of 12 t ha-1 y-1, second- and third-year juvenile harvest averages 7 t ha-1 y-1 and a surrounding 10km-by-10km area of distributed crop age would average 9 t ha-1 y-1.