Optimering av maskinsystem för skörd av ensilage med hög kvalitet

This study examines harvesting systems and presents conclusions on selection of machines for harvesting silage for dairy cows. Achieving a high quality cut of forage requires a high machine capacity and harvesting must be carried out at the optimal time with respect to plant growth stage. Therefore calculation of timeliness costs, which are determined by the time and capacity of harvesting, formed an important part of the study. These calculations require timeliness factors that describe the losses for each day by which harvest is delayed after the date of maximum economic crop value. The timeliness factors were calculated for each cut from data on changes in yield and quality of cuts during the harvest period. Harvesting cost calculations were based on a precision chop forage trailer, a precision chop forage harvester with separate transport trailers and a round baler with integral wrapping. Cost calculations were carried out for three different sizes of machine chain (small (S), medium (M) and large (L)) for each harvest system. The operations included were mowingconditioning, harvesting in the field, transport to storage and loading and packing into a bunker silo. Harvesting costs included the cost of machines, labour and timeliness. In addition, ensiling costs such as bale plastic and the investment, interest and maintenance cost for the bunker silo or the storage area for round bales were included when comparing the harvesting systems. Calculations were made for a three-cut system in conventional (CONV) and organic (ORG) forage production in southern Sweden (Gss) and central Sweden (Ss). When timeliness costs were not considered there was a risk of too low a harvest capacity being chosen. The effect of including timeliness costs when calculating harvesting costs increased with the forage area harvested, since a larger forage area increased the duration of harvest. Table S1 shows harvesting and ensiling costs with 1 km transport distance for 70 hectares of forage in conventional production and 90 hectares in organic production in central Sweden. At short transport distances (1 km), the precision chop forage trailer and the precision chop forage harvester with separate transport trailers had similar harvesting and ensiling costs, while those for round baling were somewhat higher. The precision chop forage harvester with 2 or 3 transport trailers resulted in the lowest costs at 2-7 km transport distance. At longer transport distances (>7 km), the round baler was the cheapest of the harvesting systems studied here. As regards machine capacity, it is clear from Figure S1 that to minimise harvesting costs the smallest machine chain should be used for forage areas less than 60 ha, whereas when the forage area exceeds 90 ha the largest machine chain should be chosen. In the 60-90 ha forage area range, there was little difference in costs between the S, M and L machine chains. For harvest with round bales only the size of the mower-conditioner varied between the machine chains and the largest machine chain had the lowest harvest costs for all forage areas. Machine cooperatives are a good way to lower harvesting costs since for smaller forage areas in particular, increased annual use of the machines decreases the machine costs and allows larger machines to be used to greater capacity. To avoid high timeliness costs it is important that cuts are performed at the optimal time