Field experiments for quality digestate and compost in agriculture: Work Package 2 Report - Digestate Nitrogen Supply and Environmental Emissions

The mean nitrogen (N) use efficiency (NUE) of spring bandspread food-based digestate measured in replicated field experiments was 54 ± 7% of total N applied. This was reduced to 13 ± 4% of total N applied when food-based digestate was bandspread in the autumn, highlighting the effect of N losses via overwinter nitrate leaching. Manure-based digestate applied in spring had a mean NUE of 52 ± 8% which decreased to 15 ± 6% of total N applied for autumn applications. For both materials, there was considerable variation between the NUE results obtained from the individual experimental sites; however, this was not surprising given the complex systems represented by the 15 experimental sites, including differences in soils, cropping, weather and digestate properties, and is commonly observed in experiments with other organic materials (e.g. livestock slurries).