AGRICULTURE AND ENVIRONMENT 252 58 LANDTECHNIK 4/2003 Operation Patterns of Mowing Grassland-Fauna Protection and Costs

Annette Prochnow, Potsdam-Bornim, Johann Meierhöfer, Berlin
S everal times a year mechanised grassland harvesting leads to injury and death of a large number of animals. The selection of operation working patterns for mowing effects a number of opportunities to escape for young game and birds. While trying to evade the approaching mower, the animals hesitate to leavethe shelter of the vegetation. Current working patterns cut off the escape routes of the animals, if they leave the uncut vegetation surrounded by sections already mown and thus without
more » ... ct to the adjacent fields. This is the case for conventional mowing patterns that subdivide the field into several plots (Fig. 1) and for mowing in spirals from the field periphery to the centre. These working patterns are the most common in practice. Fauna protecting working patterns facilitate the animals escape as the uncut vegetation is connected with the field edges and the animals can be expelled from the field within the cover of the standing plants [2, 9, 10]. Among these working patterns are the methods of mowing in stripes from the inside outwards or from one field side to the other as well as mowing in spirals from the field centre to the periphery (Fig. 2). Depending on the working patterns covered distances, turning time percentages and therefore field capacity, required labour time and process costs change. These parameters shall be determined for different field sizes and working widths as well as for a model farm. Approach Initially the distances travelled for the working patterns regarded were calculated [6]. Calculations were carried out for field sizes of 2-100 ha assuming a rectangular shape and a length:width ratio of 2:1. Three tractor-mower-combinations with working widths of 2.70 m, 4.90 m and 7.70 m are considered. Field capacities and operation costs for the different working patterns are referred to as the standard time ST, according to the working time structure of the Association for Technology and Structures in Agriculture (KTBL) [5]. Field capacities can be obtained from the covered distances in relation to working and driving speeds. Process costs are calculated based on guide values [8]. The model farm regarded is situated in the North of Brandenburg. An area of approximately 120 ha is mown for each cut. A standard tractor with an engine power of 101 kW and a front-rear-combination of two disc mowers with an actual working width of 5,80 m is used for mowing. The grassland spreads over 27 fields lying in close proximity to each other and most having a generally rectangular shape. At sizes of 1.4-27 ha 85 % of the fields are smaller than 15 ha. A favourable length-width-ratio can be found mainly for the smaller fields. The grassland fields are mown in conventional patterns with plot widths of 50 m. Results and discussion As expected, effective field capacities increase for all working patterns with rising field size and working width. The rise of field capacity is particularly important in the range of smaller fields with sizes up to 10 ha, while increases that can be noticed from a field size of 25 ha or more are generally insignificant. These results correspond to the Fauna safeguarding operation patterns can contribute to the protection of young game and birds. For fauna saving operation patterns, as well as for the usual bed mowing, distances travelled, percentage of turning time, field capacities, operation costs and working widths were ascertained for different plot sizes as well as for an exemplary farm. With the respective patterns, effective measures for fauna protection can be realised without additional costs