Practical considerations using Ethernet bus for a large number of sensors?
These are some considerations that come to my mind:

1) Rats - they will chew down on any wires they will find tasty enough. Laying down metal shielded cables might be costly and difficult.

2) Range - Ethernet is limited to 100 meters (328 feet). That might be a challenge.

3) Cost - Ethernet might be more expensive than other technologies.

4) Failure - If you are using a common power supply for creating the POE, shorting of one sensor might bring down the entire network.

5) Modification to the network is complex - Once you have laid down the network, moving anything around is difficult due to the wires.

6) Damage due to machinery being used in the orchard - Some worker might accidentally damage the cabling while working in the field.

Just for the sake of comparison, RF based sensors might be able to last for few years. Lora claims 10 years or so. Maintenance might be easier for these and the casing can be made strong enough so that rats don't destroy these sensors. Even if the battery lasts for 1 year, changing the battery once an year might be less time consuming as compared to maintaining the Ethernet network.