(b) Procedure
(i ) Take 3 flasks (250 ml. capacity), transfer 90 ml distilled water in each flask, plug them properly, label 1-3 and autoclave at 15 lb/inch for 30 minutes.
(ii) Collect small amount of soil from 5 different places of a desired field and mixed to make one lot.
(iii) Weigh 10 g of soil sample and transfer into flask l containing 90 ml sterilised water. It gives the dilution 1 10 (i.e. 10 1) (see Fig.2.7).
(iv) Shake the flask gently for 10 minutes by using magnetic stirrer or electric shaker to get homogeneous soil suspension.
(v) Transfer 10 ml soil suspension from 10 ditution into flask 2 containing 90 ml sterilised water to get dilution 10 4. Mix the suspension gently.
(vi) transfer 10 ml soil suspension from 10 dilution into flask 3 containing 90 ml water to get the final dilution of 10.Mix the suspension gently.
(vii) Aseptically pour 1 ml soil suspension from 10 dilution into Martin's agar plates (supple- mented with both sptreptomycin and penicillin (a each 30 mg/l). Gently rotate the plates so as to spread the suspension on medium)
(viii) Incubate the plates at 251°C for 4-5 days