The iron industry was pursued by both private entrepreneurs who owned their own smelters as well as government-supervised smelting facilities. The Song economy was stable enough to produce over a hundred million kilograms (over two hundred million pounds) of iron product a year. Large-scale Deforestation in China would have continued if not for the 11th-century innovation of the use of coal instead of charcoal in blast furnaces for smelting cast iron. Much of this iron was reserved for military use in crafting weapons and armouring troops, but some was used to fashion the many iron products needed to fill the demands of the growing domestic market. The iron trade within China was advanced by the construction of new canals, facilitating the flow of iron products from production centres to the large market in the capital city.