A great website which contains many digitized books about small farming, eco-conservation, environmental history, preventing soil erosion, and so forth...numerous topics both intellectual AND practical. All material is copyright-free and online. One example of the dozens of titles:

Handy Farm Devices and How to Make Them by Rolfe Cobleigh, Orange Judd Company, 1910
Not just nostalgia -- Cobleigh's devices and techniques were good answers to common farm problems and they're just as functional and useful now as they were then. Make your own workshop tools, a simple fence post and stump-puller, fences and gates that don't sag, building a farmhouse, barns and outbuildings, a bicycle-powered washing machine, a dog-powered pump, a lightweight orchard ladder, a portable chicken coop, a stone boat (for moving stone) and much more. Cobleigh's out to save you time and money -- a treasure for small farmers or homesteaders and anyone wanting to be more self-sufficient. Illustrated, good old-style writing, punctuated with quotes from Shakespeare or a local farmer, whichever's apt.