Winter asparagus production with hot water heated by pellets boiler
Asparagus fusekomi forcing culture system is very intensive with high heating costs during winter production. An alternative energy source instead of oil or electricity can contribute to a low carbon strategy. The warming system by wood pellet heating consists of 3 components: 1) pellet boiler, 2) hot water storage tank (6,000 L for growth medium warming and 1,000 L for air warming inside the tunnel) and 3) asparagus cultural bed (80 cm in width 9 m in length 45 cm in height) in a plastic house. The cultural bed was covered with plastic sheet every night and day under cloudy condition. Pellets are automatically supplied to the pellet boiler from a pellet tank. The pellet boiler warms the water to 50°C in the two hot water storage tanks. Hot water is circulated when soil temperature of the growth medium and air temperature inside the tunnel decrease below 20°C. By circulating the hot water, the soil temperature of the growth medium can maintain an average of 20°C in mid-winter, and the warming effect is not inferior to an electric wire. There was no difference between the spear yield from 1 year old rootstocks by boiler heating and that by electric wire heating in winter production, in 2011. When the outside temperature fell to -10°C, air temperature inside the plastic house became close to 0°C at night, whereas the temperature inside the tunnel was 12-20°C, and freezing injury was not observed in spears that emerged. The night temperature inside the tunnel influenced spear growth, and the spear yield per month in the heated tunnel showed approximately twice that in the unheated tunnel in mid-winter, 2012.
Araki, H., Nakano, H., Ichikawa, S., Kawai, T., Jishi, T., Yamagata, S. and Kamide, M. (2020). Winter asparagus production with hot water heated by pellets boiler. Acta Hortic. 1301, 117-122
forcing culture, pellet heating, hot water, temperature, plastic house, winter