Should I enter a farm expense of a new drainage field for the house under assets to be deducted over several years or just under other expenses?

[TomK]

This is an improvement to your property that must be depreciated as a capital expense (page 25, no. 9 under Capital Expenses).  Tile drainage systems have a property class life of 15 years. This is more commonly referred to as the useful life of the asset.

Farmer's Tax Guide: https://www.irs.gov/pub/irs-pdf/p225.pdf