Biofumigation is defined as the use of biologically active plant substances to control soil-borne pests and diseases in agriculture and horticulture. It is based on incorporating soil amendment (fresh plant mass, manure) into the soil, which will release several substances, known as isothiocyanates (ITC’s), able to suppress soil-borne pests, plus a soil heater to enhance biological activities. Plants from Cruciferae family (Cabbage, radish, cauliflower etc.) release large amount of these toxic substances in the soil and are considered the best material for biofumigation.
The technique is useful for
- Suppressing certain soil-borne pathogens
- Bringing more flexibility to crop rotation
- Harnessing the positive effect of catch crops
- Organic farming greenhouse cultivation
Effect of biofumigation
Proven advantages of crop cultivation are promotion of the soil’s water-retention capacity, structure and aeration. By additionally applying the biofumigation technique, you can introduce plant substances into the soil, where they help to combat soil-borne diseases.
Cruciferous plants contain glucosinolates, which is at its highest concentration when the plant is flowering.
When the plants are finely chopped (chaffed) and worked into the soil, the glucosinolates are converted enzymatically into isothiocyanates, the actual active ingredients. These target the active stages of pests such as fungal mycelia, mobile nematodes or germinated weeds.
How to do it:
- Incorporate the fresh mass into the soil. This can be done directly if the mass is coming from grown crop or with mass taken from other side and brought into the plot or field. If the mass is transported to the field, the soil should be well prepared before the incorporation. During transportation and storage of these organic materials in the field, care must be taken not to lose the gases produced from biodegradation, by covering the piles of the biofumigant with plastic until the time of application.
A dose of 50 t / ha is recommended, although when problems with nematodes or fungi are very serious, 100 t / ha should be applied, a dose that can be reduced by chosing a cultivation techniques such as application in furrows.
The biofumigant should be distributed uniformly, so that no concentration of pathogens will appear that could create problems for the crop. Once the biofumigant is distributed, it should be incorporated immediately into the soil.
- Water the field, if possible by sprinkling, until the soil is saturated, although watering can be done by flooding, or drip irrigation can be installed.
- Cover the soil surface tightly with a transparent plastic film for at least two weeks to retain the gases produced from the biodegradation of the organic matter. This could be the same plastic as the one used for soil solarization.
- The film is removed 3-4 weeks after and the soil slightly removed in order to permit the gases to escape from soil.
- Planting of the interested crop can be done 24 hours later.