custom field in the IPN of paypal adaptive payment

Question

I have implemented Adaptive Payment in my website. First It was Standard Payment so in that i was passing a custom parameter in the form and i was getting it i

Answer 1

I agree with @jimy to use the querystring, but in PayPal Adaptive the parameter is not notify_url.

For PayPal Adaptive use the ipnNotificationUrl field of the Pay or Preapproval request

Source: Identifying Your IPN Listener to PayPal