Effect of mechanical conditioning, windrow handling, and maturity on the drying rate of timothy hay in a wind tunnel

摘要

Three experiments were carried out to evaluate windrow handling treatments on the drying rate and time to reach a target moisture at three maturity stages of timothy. A number of consistent effects were observed among the treatments. Compared to a wetsoil, a dry soil reduced the drying time by 13 h at the boot stage and by 5 h at the early heading stage. When moving or turning windrows, it is therefore preferable to lay them on the dry stubble previously exposed to direct sunshine rather than to laythem back on the wet, previously covered stubble. Mechanical conditioning using three grooved rolls reduced the drying time consistently but moderately (4, 9, and 5 h for experiments 1, 2, and 3, respectively at three maturity stages). Inversion 24 h after mowing reduced the drying time by 6 h (experiment 1) whereas inversion 48 h after mowing did not result in any significant time saving (3 h for experiment 1 and none for experiment 3). A lower mass per unit area consistently reduced the drying time.In experiment 2, drying time averaged 47 h at 1.25 kg DM/m~2 and was reduced by 3 h at 0.94 kg DM/m~2 or by 7 h at 0.63 kg DM/m~2. In experiment 3, a forage mass per unit area of 0.54 kg DM/rrr required 4 h less time to dry than a forage mass per unit area of 1.08 kg DM/m~2 (32 vs 36 h total time). A combination of several factors can speed up drying in the field and reduce the time during which windrows are exposed to rain, bleaching, and plant respiration. Based on this study, a number of recommendations can be made to reduce the field drying time for the production of marketable hay or herbage biomass. These include; (1) spread the windrows over the widest possible area; (2) invert windrows 24 h after mowing rather than 48 h; and (3) apply some formof mechanical conditioning.