when GST registration is required

(1) Turnover is more than 20lakh, but deals in items, which has no gst,like paddy, green vegetables. If so, then GST registration is required or not.
(2) If the person also has a turnover 5lakh/pa from rental of construction machinery and the total turnover exceeds the threshold limit of 20lakh, what about gst registration.
Looking forward to your valuable suggestions....