Thermal Band Heating for Intra-Row Weed Control

Summary

For many years, disinfection of the soil by means of steaming has been a common method for eliminating weeds and fungal diseases. However, surface steaming of soil is a very energy-intensive process, and consequently, efforts have been made to develop a machine for narrow-band steaming of the soil under and around rows of cultivated plants prior to seeding. The use of this machine may achieve up to 90% energy savings, and will also reduce the amount of damage to the flora and fauna. A special test rig has been developed with the objective of obtaining new information about narrow-band soil steaming. The test rig consists of a revolving ditch, in which the soil can be heated by means of submerged steam jets. The rig is equipped with thermosensors for measuring temperatures in the steamed band during the process. For a more detailed analysis of the temperature profile in a cross-section of the processed band, an apparatus has been developed especially to record the temperatures obtained at 63 locations and at seven levels across the ditch. On the basis of the results from the test rig, a prototype band-steamer for field use has been developed. Tests have shown that soil temperatures exceeding 70C will be needed to protect against germination of weed seeds. For band heating such a treatment in 50 cm rows requires about 5.8 GJ/ha.