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Crop mergers: Management of soil contamination and leaf loss in alfalfa

M. F. Digman, K. J. Shinners, M. E. Boettcher
Applied engineering in agriculture 2013 v.29 no.2 pp. 179-185
Medicago sativa, alfalfa, ash content, biomass, crops, cutting, energy use and consumption, equipment performance, experimental design, field capacity, forage harvesters, forage quality, fuels, leaves, mechanical harvesting, models, rakes, tractors, water content
Maximizing the capacity and subsequent efficiency of the forage harvester necessitates consolidation (raking or merging) of alfalfa cuttings. Although rotary rakes are in wide use, the use of continuous pickup belt mergers is increasing in the Midwestern U.S. Previous work on crop consolidation is limited to rakes and inverters available during the time period and, therefore, does not consider modern merger designs or harvesting practices. In this study, field capacity, leaf loss, and the extent of ash (soil) incorporated into windrows was investigated by on-farm observation and through a controlled experiment. The experimental portion employed a factorial design to study the influence of two moisture levels (60 and 40% w.b.) and three cutting heights (5.1, 7.6, and 10.2 cm) on the ash incorporation and leaf loss of a belt merger. In the controlled experiment, windrow ash content increased statistically, but not practically, with lower cutting heights and lower swath moisture. Managing windrow ash with cutting height resulted in an average yield loss of 0.3 Mg ha-1 cm-1. Leaf loss was observed to increase with decreased swath moisture from 1.1 to 2.2% of total biomass. The on-farm survey included four operations including two owner-operators and two custom-operators, as well as five separate machine-tractor-operator combinations. Here, a variety of merging practices were revealed, yielding a range of theoretical field capacities from 13.2 to 16.9 ha h-1. Each operation managed tractor engine speed below rated PTO speed, resulting in fuel rates between 18.2 and 21.3 L h-1, which were less than predicted by ASABE models. As with the experimental work, the use of a belt type merger did not cause significant amounts of windrow contamination.