I have been growing apple trees for three years. First year, 2-4 apples on each tree, then no fruit. This year 5-7 on each tree. . . . .
Certified GKH Gardening Expert
This could be due to poor pollination or something lacking in the soil. It could be low on phosphorus, which is responsible for flowering and fruiting. I would have your soil tested to see what, if anything, is missing and then fix it accordingly. These articles should help: https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm