Open access publications in the SLU publication database

Abstract

Weed control by freezing has been compared with flaming in order to find out if it can be a complement to the methods used today. Two different media has been used for weed control by freezing; liquid nitrogen, which has a temperature of -196 °C, and carbon dioxide snow, which has a temperature of -78 °C. Liquified petrolium gas (LPG) was used for flaming. During the summer of 1991, the effects of varying doses of liquid nitrogen, carbon dioxide snow and flaming where compared in field trials. Weed control by freezing with liquid nitrogen or carbon dioxide snow is a method that works. The method can be used more or less in the same way as flaming. Trials so far, however, show that freezing consumes more energy than flaming to reach the same effect on dicotyledonous weeds. Compared with flaming, freezing with liquid nitrogen consumes three times as much energy and freezing with carbon dioxide snow consumes six times as much energy, to reduce the number of weeds by 90%. Weed control by freezing is an expensive method because of the large quantities of freezing media required to obtain good results. The equipment used to spread the freezing media on the weeds is a very simple experimental model. It can probably be improved in order to be more energy effective. Even if this is the case, it is probably difficult to develop the equipment for freezing to such an extent that freezing can compete with flaming as a method for weed control. Although under certain conditions, freezing might be a useful method, for example in places where there is a great risk of fire.