Recycling nutrients from horse manure: effects of bedding type and its compostability

Manure constitutes a nutrient resource that should be efficiently recycled in agriculture. We assessted the nutrient cycling properties of three bedding materils (peat, wood shavings and pelleted straw) in horse manure by comparing their compostability, ability to retain nitrogen (N) and phosphorus (P) under rainfall and capacity to release N when mixed with soil. Manure with pelleted straw bedding had superior composting characteristics as it lost half of its dry mass, reached temperatures >60 oC and ended up having a carbon (C) to N (C:N) ratio of <15. In percolated water, 4-11% of total manure N and 5-23% of total manure P was leached during a 2 h 15 min event of artificial rainfall. Peat manure was most susceptible to P loss. In all fresh manures, C:N ratio exceeded 30, which led to net N immobilization in soil. Composting decreased the C:N leading to a slight positive or an insignificant fertilizer effect.