The tree gave lots of fruit last year, but this year fruits are there but leaves and fruit are small. Does it need fertilizer, and if so, what kind? Does it also need lime and zinc as someone else suggested or any other nutrients?
Regarding Lemon Tree in My Garden
Certified GKH Gardening Expert
They sell citrus specific fertilizers, if you want to go that route. This article also has information about what lemon trees need:
I would not adjust the micro nutrients (such as zinc) or the pH (with the lime) unless you have had a soil test done. Many local extension offices will do soil tests for a small fee. Or you can send a soil sample to UMass Extension and they will do a soil test for you. Here is information on doing that: