Do I still need to buy social security after buying agricultural insurance?

You don't have to apply for social security if you apply for a new rural insurance. For inter-provincial and inter-city transfer, the procedures need to be applied to the social security bureaus of the two places respectively, and only personal accounts can be transferred. Personal accounts and overall accounts cannot be taken away together, so be prepared psychologically.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.