A third type of decomposition was brought into prominence by Liebig in 1840.[7][B] Reviewing the decomposition of organic matter in the light of the newer chemistry, he concluded that the process was a slow chemical oxidation, to which he gave the name “Eremacausis.” He recognised that humus was formed, but he regarded it only as an intermediate product, and emphatically denied its importance in soil fertility. The true fertility agents, in his view, were the final products--CO₂, potassium and other alkaline salts, phosphates, silicates, etc. He went on to argue brilliantly that instead of applying farmyard or similar manures to the soil it was altogether quicker and better to apply these mineral compounds obtained from other sources than to wait for the slow process of liberation as the result of decomposition. For some reason, difficult to understand, he overlooked nitrification and the part that nitrates might play in soil fertility. Lawes and Gilbert[6] were much attracted by this new idea; they showed that it was incomplete because it took no account of the necessity for supplying nitrogen compounds to the crop. When ammonium salts were added to Liebig’s ash constituents the resulting mixture had almost as good a fertilising effect as farmyard manure. Lawes at once saw the enormous practical importance of this discovery, and set up a factory for the manufacture of artificial fertilisers. He did not, however, follow it up more closely on the scientific side. [B] The numbers refer to the short bibliography on p. 18. Both Lawes and Gilbert were in constant touch with the idea of decomposition in the soil, and they attached so much importance to nitrogen compounds in plant nutrition that it is not easy to understand how they missed the connection with nitrification. But they did so, and like other English and German workers of the day, considered that plant roots assimilated their nitrogen as ammonia. For the first ten years of the history of Rothamsted only few experiments with nitrates were made, and not till thirty-five years had elapsed were they systematically studied.