Design Experiment 2

Fresh solid dung was collected in September 2016 from dairy cows in the yard and nearby dairy fields over a number of days, avoiding urine and fresh grass residues. Dung was stored at 4 °C for up to 2 weeks and then mixed and homogenised using a drywall mixer. Simulated dung pats (DP treatment) were applied on 3rd of October using a defined fresh weight (2 kg) of dung. Each dung pat had a defined diameter of 30 cm. Dung pats were placed on a plastic mesh (10 mm mesh size) on short mown grass sward, pressed down by their own weight and covered with chicken wire for bird protection. Dung pats were placed in a randomized block design with five blocks (Additional files 2 and 3) each block containing six temporal replicates of the DP treatment and NDP treatment and additional measurements. The distances between sampling blocks were at least 2 m but usually greater (Additional file 3). Sampling intervals were timed as for Experiment 1; however, an additional sampling run was carried out after 6 months (10th April 2017) to test for dung legacy effects (see Table 2).

Timing of dung pat applications and sampling runs, shown as dates and time elapsed since dung application