Agricultural, floricultural and horticultural pursuits, including but not limited to, general farms, greenhouses, plant nurseries, truck gardens, dairy husbandry, animal husbandry and poultry and livestock, together with all customary buildings and other structures necessary for the production and storage of the products of such pursuits, provided that buildings, pens and runways for the confinement of livestock or poultry shall be at least 100 feet from any property line of an R District and no manure or other odor- or dust-producing substances shall be stored within 100 feet of any lot line.