The timber and tobacco industries strip off hundreds of tons of bark from pine logs every year. These are chipped and composted before being sold. Bark makes an excellent mulch for organic weed control. However it has virtually no nutrient value and two big disadvantages as a soil conditioner. Firstly, it is very expensive. Secondly, and perhaps more importantly, it is a very hard marterial in a virtually unrotted state. The lignin in bark takes a long time to break down so the bacteria use even more nitrogen in the rotting process. Unless you are prepared to add large amounts of nitrogen fertilizer to your soil, it is better to use another material as a soil conditioner and use bark, purely as a mulch.
Having said that bark is a renewable resource and pine bark is one of the most widely used components in commercial planter potting media, although barks from many other species are also processed for this purpose. Bark lacks the moisture-holding capacity of peat moss, but it can dramatically increase the porosity of a mix. Bark particles used in container media generally range in size from dustlike to about 5 millimetres in diameter.