Which of the following is/are bio fertiliser used to add, conserve and stimulate phosphorus as a plant nutrient in the soil?
1. Azospirillum
2. Mycorhizal fungi
3. Azotobacter
Select the correct answer using the codes given below.
1
Only 1 and 2
2
Only 1
3
Only 2
4
All 1, 2 and 3