All brassicas contain constituent compounds called glucosinolates to a varying degree . In the correct condition some of these glucosinolates produce active compounds which are useful in the suppression of pathogens and smoke . The internalization of these dynamic compounds into the soil is the process of biofumigation . There are also other benefits from the process , as Tozer Seeds explicate in their article .
The science of biofumigationBrassicas moderate three key ingredients ; glucosinolates , an enzyme called myrosinase and water . The cell of the flora computer storage glucosinolates and myrosinase separately . They only meet when the cell of the flora are damaged . When body of water ( from the flora itself or from the soil ) mixes with them , it organize glucose and a junior-grade chemical compound . The secondary compound breaks down further into volatile compound include isothiocyanates ( ITCs ) .
The isothiocyanates are toxic , explosive compounds which can be used to suppress pathogen and gage . ( Metam Sodium is a synthetical form of ITCs which is no longer uncommitted ) . When herbivorous insects eat the plants this causes the natural occurrence of ITCs . In fact the plants use the chemical mechanism as a defence reaction to being nibbled . Mechanising the summons of cutting and bruising the plants by using a flail and a rotavator will enhance the chemical reaction .
Biofumigation using a covering cropGrowing a brassica as a cover crop is the best way to use biofumigation . Not only do you farm the ITCs which will crush the pathogen and skunk , but also you tot a huge amount of constitutive matter which enhance the capacity of the good microbe in the soil which in turn will be a good defence against pathogen . Also it help appropriate nutrient and as brassicas have cryptic ancestor they help with drainage .
Although most of the ITCs are produced from the process of damage the plant , there is also some natural secernment of glucosinolates from the ancestor . Microbes break down these compounds as they require to obtain the glucose and in twist this which will develop ITCs .
How to optimize BiofumigationThe two primary aims are:1 . Maximise the glucosinolate concentration2 . Maximise the biomass ( loudness of material)• 10 tonnes of dry issue per ha• 50 tonnes of sassy subject per ha
Implementing craw direction will facilitate accomplish these aims . Careful timing of the steps will obtain the undecomposed results so it is useful to understand the crop requirements as this will assist in decision fashioning . Steps1 . Choose the most appropriate species.• The most consistent brassica is Indian Mustard ( Brassica juncea)• Rocket can be used but this will not give produce enough biomass• White mustard ( Brassica alba ) does n’t produce ITCs
2 . Site selection:• pH of the ground issue ITC production . It must be over pH 5• a high-pitched constitutive subject content in the soil could result in the ITCs binding to this rather than being released into the soil .
3 . Sowing Dates:• early on as potential – June / July ( if outside)• Long day length , mellow UV and warmth will produce highest biomass and higher measure of glucosinolates
4 . Nutrients:• To incur a high glucosinolate content the program of Sulphur at 25kg / ha is recommended• To obtain a mellow biomass the program of Nitrogen at 100kg / ha is recommended
5 . Cutting• The average originate time is 10 - 14 weeks• Cut at the early unfolding stage to maximise the glucosinolate depicted object . Once there is 50 % bloom the glucosinolate content reduces.• Soil temperature needs to be above 8 ° C for compounds to work• Soil must not be ironical – either fourth dimension cutting with pelting or irrigate.• The chopped stuff needs to be incorporated forthwith as the volatile compounds are lose within the first 5 hours – the best way to do this is with a front mount flail and back mounted rotivator .
6 . Sowing Cash Crop• Biofumigation will take place within 24 - 48 hours• However other gases will be released and so it is good to wait between 10 - 14 days before institute into the soil.• Do a Cress Test to make certain that all chemical reactions have finished.• Take some soil and put it in a jar• Cover with a damp paper towel• Sprinkle with Cress seeds• Germination should happen in 2 - 3 days , if this does n’t happen wait a few more day before planting hard currency crop .
benefit of using Biofumigation1 . Suppresses pathogens such as PCN ( Potato Cyst Nematode ) , wilts in eggplant , peppers and strawberries2 . Also suppress weeds3 . Enhances the soil complex body part and the microbiome of the soil by incorporating a heavy amount of organic subject . study at SASA have shown that there may some short condition damaging effects to the microflora in the filth but this bounced back cursorily due to the growth in organic matter .
