earthworm 2 populations 3 4 5

30 In repeatedly mown and mulched green manure leys, the mulched herbage contains substantial amounts of 31 nitrogen (N), which may only slightly contribute to the following crops ́ nutrient demand. The objective of the 32 present work was to evaluate the effect of alternative strategies for green manure management on the yield and N 33 recovery of a subsequent spring barley crop, and their short term effects on soil structure and earthworm 34 populations. A field trial was run from 2008 to 2011 at four sites with contrasting soils under cold climate 35 conditions. We compared several options for on-site herbage management and the application of anaerobically 36 digested green manure herbage. Depending on the site, removal of green manure herbage reduced the barley 37 grain yield by 0% to 33% compared to leaving it on-site. Applying digestate, containing 45% of the N in 38 harvested herbage, as fertilizer for barley gave the same yields as when all herbage was mulched the preceding 39 season. Overall, the apparent N recovery was enhanced from 7% when all herbage was mulched, to 16% when 40 returned as digestate. A positive effect on earthworm density and biomass was seen after one season of retaining 41 mulch material, rather than removing it. Digestate did not affect the earthworm population, but contributed to 42 higher soil aggregate stability. In conclusion, for spring barley production after green manure ley, the digestate 43 strategy increased N recovery and reduced the risk of N losses. The yield of the succeeding barley crop yield was 44 reduced when N in herbage was not returned as mulch or digestate. 45 46