Abstract
Recently, various manure handling systems have been introduced into the dairy farming systems to reduce the pollution caused by livestock waste. However, the nitrogen load such as ammonia emission or the fossil energy consumption by the manure treatment might be increasing with the development of the livestock production, although the main purpose of the manure handling system is to recycle livestock manure efficiently. It is anticipated that the environmental points of views should be taken into consideration when evaluating manure handling systems.
In this paper, evaluation using two combined indexes, [Fossil Energy Input for manure handling/Net Agricultural Income] Ratio; (FEIm/NAI) and [Nitrogen Load by manure handling/Net Agricultural Income] Ratio; (NLDm/NAI) were conducted on three dairy farming systems having different manure handling systems; slurrygation system at a free stall dairy barn (system A), drying and composting at a free stall dairy barn (system B) and traditional solid and liquid separation system at a stanchion stall dairy barn (system C).
FEIm/NAI ratios for system A, B and C were 65, 17 and 13 [MJ/1, 000yen], respectively. NLDm/NAI ratios were 0.07, 0.32 and 0.06 [kgN/1, 000yen], respectively. These results show the environmental road caused by manure handling per agricultural income was comparatively smaller at system C having traditional manure handling system than at system A and B having advanced manure handling systems. From the evaluation of combined indexes in this study, it was indicated that the environmental load by advanced manure handling systems has not always reduced envirnmental load even though the advanced manure handling systems would be efficient and labor-saving.
