Most of the drying happens on the field.
During the first cut, process the forage on the ground at least three times with the rotary tedder, each time with decreasing speed and increasing gentleness. Alternate between longitudinal and transverse direction of travel, set the rotor rather flat for turning. Pre-drying time: normally from 24 hours. Usually mowing is done on the first day, and the following day late in the afternoon.
Every installation has limits.
Do not bring in the hay too moist or in too large quantities and always before sunset! Layer height depending on moisture, type of forage and system design max. between 1.5 and 4.5 m. The first layer should be at least 1.5 m high. For round bales, the moisture content should not significantly exceed 35%.
Loading is decisive.
A cutting device with three to six (sharp!) knives in the loader wagon facilitates distribution, but is not necessary for very young forage. Very moist wilted hay can also be loosened up with metering rollers. Distribute hay loosely and evenly in the box, switch on fan after about one meter of layer height, switch dehumidifier systems to fresh air operation for the time being. Distribute unevenly moist forage over the entire area by shaking the gripping tongs. Enter the hayloft only in case of emergency.
For round bales, pressing is the decisive factor.
Press round bales from a slightly spaced, loose double swath at low pressure and high driving speed so that there is uniform density of the bales from the inside to the outside, but also in the longitudinal direction. Likewise, make sure that the bales in a batch are of the same type. Press pressure at 60 to 80 bar depending on type, set density distribution evenly, activate or switch off prepressure accumulator as required. Check the bale density on the basis of the bale weight.
The current operations
If a control system is available, select the drying time according to the moisture content and quantity of the fresh material. After switching on, allow the system to run for at least 24 hours. Check the temperature of the hayloft and exhaust air several times and observe any compaction points or chimney formation.
Bad weather program
In bad weather and cold ventilation, ventilate intermittently for cooling. Otherwise, switch on warm-air furnace, heat exchanger or dehumidifier, if possible. At outdoor temperatures below 25 °C, it is better to operate the dehumidifier with circulating air. The hay temperature must never exceed 40 °C!
Monitor static pressure and hay temperature.
Check the hay rack for too rapid settling and monitor static pressure with a U-tube. Very high pressure reduces the air flow and increases the necessary drying time. Pressure monitoring is especially important for older fans with low pressure reserve. Also, a strong resistance when opening the door of the fan chamber may indicate that the system is overloaded.
Avoid surface condensation in fresh air mode by using exhaust air openings, in dehumidifier recirculation mode by good exhaust air recirculation or by thermal insulation. Thermal insulation is particularly advantageous in dehumidifier recirculation mode. The underlayment of a roof extraction system also acts as insulation to counteract condensation in the building.
Keep an eye on everything.
Constantly monitor the temperature of the dried material, exhaust and supply air. Towards the end of drying, walk barefoot over the hay to check for drying and possible chimney formation. The moisture content of the hay can be roughly estimated from the moisture content of the exhaust air.
Final inspection and re-aeration.
If the exhaust air humidity is already low or the temperature difference between the supply and exhaust air is small (e.g. 2 °C), switch to interval operation with cold air. If, when switching on again after a few hours of standstill, the exhaust air humidity is below 50 %, storage capability has normally been reached. Round bales are only ready when a long round steel mandrel can be pushed into the bale from all sides without great resistance. Damp spots are tough! Nevertheless, continue to check for self-heating. If necessary, re-aeration must be carried out.