Biological Soil Disinfection (BSD) or ‘soil resetting’ can technically, energetically and economically be an effective alternative to soil steaming. The program ‘Greenhouse as energy source’ of the Ministry of Economy, Agriculture and Innovation and the Dutch Horticultural Board gave fi nancial support to practical demonstrations and further development of this technology, in order to stimulate implementation of BSD in practice. Chrysanthemum growers, DLV Plant B.V., Wageningen UR Greenhouse Horticulture and Thatchtec B.V. gained experience with BSD in four chrysanthemums companies. Additional research was conducted into possibilities to speed up the process and fi nd reliable process indicators. The disinfection and cultivation results (up to 5 cycles) was after BSD as good or better as after steaming in 3 of the 4 companies. Anaerobic conditions, one of the prerequisites for disinfection, were not achieved in the fourth company, which may explain the unsatisfactory disinfection. In intensive cultivation, three weeks without cultivation need to be included in the planning. Implementation in July offers the best fi t in terms of effectivity and income.The process can be shortened to 9 days by means of a higher Raw Proteine dose, but this leads to growth inhibition in the next cultivation. Adding a “primer” or “inoculum” with own soil bacteria does not suffi ciently increase the operational reliability, and is therefore deleted as a process step in the protocol. The disinfection process can be well monitored by means of oxygen measurement and total nematode counts. Additional indicators are the concentrations of nitrate, ammonium and bicarbonate in the 1:2 soil volume extract
