Effect of harrowing and watering on disappearance of dung pats in pastures

Dung pats in pastures limit grass production, and lead to grazing losses and a lower eco-efficiency in dairy systems. Immediate harrowing after grazing could help to break up the pats and distribute the manure more evenly. However, in the absence of rain this may result in flattened, manure-smeared grass. Harrowing after some days of dung deposition may overcome smearing of the grass. Watering the pasture immediately after harrowing can help to wash the manure off the foliage. In a field experiment we compared the disappearance of (artificial) dung pats in the following treatments: (1) dung pat – untreated (control); (2) harrowing immediately after deposition (day 0); (3) harrowing + watering (10 mm) immediately after deposition (day 0); (4) harrowing at 7 days after deposition; and (5) harrowing + watering (10 mm) at 7 days after deposition. The results after three weeks show that harrowing fresh dung pats (day 0) did not significantly increase the disappearance of dung (43% disappeared versus 40% disappeared of the untreated pats). Harrowing 7 days after deposition resulted in a significant lower dung disappearance (31%) than observed for the untreated pats (40%), even when watered (34%). The best result was obtained when fresh dung pats were harrowed in combination with water at day 0 (61% disappearance).