I. THE ECOxXOMlCAL USE OF MANURES AND 

 FERTILISERS. 



One of the urgent needs of the present time is to make the most 

 economical use possible of all manures and fertilisers. Farmyard 

 manure is by far the most important of these^ the quantity used on the 

 land exceeding many times in weight and value all other fertilisers. 

 It is estimated that 37,000,000 tons per annum are made in the United 

 Kingdom, of a value of not less than £11.000,000 ; all other fertilisers 

 put together did not before the war much exceed £4,500.000 in value 

 and 1.000,000 tons in weight. It has long been known that farmyard 

 manure suffers serious loss as handled on an ordinary farm ; good 

 esiimates show that at least half its nitrogen, its most useful con- 

 stituent, is usually wasted. Through the generosity of Capt. the 

 Hon. Rupert Guinness it has been possible to investigate the nature of 

 the loss and show how it arises. Two causes were found to operate, 

 exposure to weather and the penetration of air into the heap ; both 

 led to considerable loss, and when both act together, as they do on so 

 many farms, especially dairy farms, the aggregate loss is very consider- 

 able. Methods of dealing with the loss due to exposure are easily 

 suggested, and when carried out they have led to considerable en- 

 hancement of crop-producing power. The exclusion of air is more 

 difficult and would involve a new method of storage. It is found that 

 manure kept in complete absence of air at a temperature of about 26° C. 

 not only loses no nitrogen but positively gains in other ways, notably 

 in that its complex nitrogenous constituents are broken down into 

 highly valuable ammonia. Unfortunately these ideal conditions are 

 not attained in ordinary practice, and Mr. Richards is attempting 

 to find a way of realising them ; this work is being carried out on the 

 Home Farm at Hoebridge, Woking, where Captain Guinness has 

 provided all necessary facilities. At the outset the investigation is 

 being confined to the simplest case, the conservation of liquid manure ; 

 afterwards we hope to pass to the more difficult problem of whole 

 manure. 



In the past farmyard manure has been studied mainly as a source 

 of nitrogen, but investigations made at Rothamsted and elsewhere 

 show that this is too narrow a view of the problem and that other 

 organic constituents may also play an important part. 



A considerable part of the manure heap is made up of straw, which, 

 as farmers have long recognised, must undergo a certain amount of 

 decomposition before the best results can be obtained. Our experi- 

 ments show that the unchanged straw goes far to neutralise the benefits 

 of the other components and in extreme cases it may actually 

 depress the crop, ('ertain changes in the cellulose and other carbo- 

 hydrate constituents are essential, and experiments are in hand to 

 ascertain what these are and how they are brought about. 



Work in this direction is carried out by Dr. Hutchinson and Mr. 

 Richards. Dr. Hutchinson has shown that the decomposition of 

 cellulose is effected l)y an organism of peculiar morphological character- 

 istics, the knowledge of which has enabled him to account for some of 

 the discrepancies in previous work. The conditions and nature of the 

 action are under investigation. 



For the moment, however, the centre of interest is the connection 

 of this decomposition with anotiier change of supreme agricultural 



