2o6 



NATURE 



[April 15, 1920 



in the knowledge of the special subjects of the 

 dissertations; for at some universities professors 

 who have never published anything- whatever are 

 asked, as professors, to examine, for the doctorate, 

 candidates with a European reputation ! An in- 

 stance of this nature has recently occurred in one 



of the universities in this country, the professors 

 being almost unknown outside its walls. But no 

 doubt Oxford and Cambridge may be trusted to 

 stand above rendering such an injustice to those 

 who seek their recognition and come from afar for 

 the benefits they bestow. 



British Crop Production.'^ 



By Dr. Edward J. Russell, F.R.S. 



pj* ODDER and hay crops play a more important part 

 *• than cereals in the economy of the farm, because 

 they are the raw materials for a highly important pare 

 of the farmer's business — the production of meat, 

 milk, or butter. They are too bulky to transport in 

 any quantity, and farmers use only as much as they 

 themselves grow. The output of meat and dairy pro- 

 duce is, therefore, limited by the quantities of these 

 crops at the farmer's disposal. The quantities pro- 

 duced just before the war and in 1918 were : — 

 Production of Fodder and Hay Crops. 



yield per acre Acreage. 



1908-17 Millions oi acres 



, ■-- , r ' ^ 'Jotal 



England United England and United produce. 



and King- Wales Kingdom Millions of 



Wales dom ' ^ ^ ' ^ tons 



tons tons 1914 1918 1914 1918 1914 1918 



Swedes I3'0 146 i"04 0*91 1*75 i-6o 24*2 22-8 



Mangolds ... 195 195 0-43 041 0-51 0-50 9*5 10-3 



cwt. cwt. 

 Hay (temporary) 291 32 2 15s i'45 290 2-80 42 4*4 

 Permanent grass 22'6 279 479 4*30 6*49 595 h^^ 7*9 

 Like cereals and potatoes, these crops are greatly 

 affected by artificial fertilisers, especially by phos- 

 phates, which increase not only the yield, but also 

 the feeding value per ton. This is strikingly shown 

 in the case of swedes and turnips, which receive a 

 large part of the superphosphate made in this country. 

 Mangolds respond remarkably well to potassic fer- 

 tilisers and to salt. There is much to be learned 

 from a systematic study of the influence of artificial 

 manures on the composition and feeding value of 

 these crops under the varied conditions of this 

 country, 



A further reason for the important part played bv 

 these crops in the economy of the farm is that they 

 profoundly affect the fertility of the soil. They do 

 not remove from the soil all the fertilising constituents 

 which must be added to secure maximum growth ; 

 some of these constituents are left behind in the soil 

 to benefit the next crop — a rare instance of double 

 effectiveness for which the farmer ought to be pro- 

 foundly thankful. In the second place, even the fer- 

 tilising constituents which are absorbed by the crop 

 are not entirely retained by the animal ; considerable 

 quantities are excreted and pass into the manure, and 

 again are added to the soil. There is, therefore, the 

 possibility of constant improvement of the soil ; 

 larger fodder crops enable more livestock to be kept, 

 niore livestock make more manure, and more manure 

 gives still larger crops. It is sometimes argued that 

 meat or milk production is in some wav opposed to 

 corn production, but on this method there is no 

 antagonism ; on the contrary, each helps the other. 

 The production of more meat is consistent with, and 

 indeed involves, the production of more corn. 



The simplest way of utilising animal excretions 

 without loss is to allow the animals to consume the 

 crop on the land where it grows, and this is frequently 



1 Discourse de'ivered at the Royal Institution on Friday, February 20. 

 Continued from p 178. 



NO. 2633. VOL. IO5I 



done excepting where the soil is so stickv as to 

 become very unpleasant in wet weather. Sheep are 

 the best animals for the purpose, as they are easily 

 penned in by light hurdles, these being moved as 

 each portion of the field is cleared; this folding is a 

 common occurrence on the chalky and sandy soils of 

 the Southern and Eastern Counties. 



Bullocks are less tractable, and cannot be enclosed 

 by light hurdles; they are, therefore, generally kept 

 in yards, roofed in if possible, but oftentimes open. 

 Sufficient straw is added to provide them with 

 bedding and to soak up the excretions. In this wav 

 the fertilising constituents of the straw as well as of 

 the food are returned to the soil. 



In the case of dairy cows the treatment is rather 

 different ; they have to be housed properly in quarters 

 which are sometimes palatial, and forhvgienic reasons 

 they are allowed but little bedding. 'Their manure 

 is _ removed once daily — sometimes oftener — the 

 primary object being to get it awav without con- 

 taminating the milk. The investigations alreadv 

 referred to for which Lord Elveden provides the 

 funds are now being extended to the dairy farm to 

 see how far it is possible to save the manure without 

 prejudice to the purity of the milk. 



In the old days, when farmyard manure was the 

 only manure and- the old type of implements alone 

 were available, farmers had to arrange their crops 

 on a definite plan in order to get through their work 

 and maintain permanently the productiveness of the 

 land. There thus grew up a system known as the 

 rotation of crops, which contributed verv largely to 

 the agricultural developments of the 'sixties, "and 

 j ultimately became a rigid rule of husbandry strictly 

 I enforced over large parts of the country. " Modern 

 I cultivation implements and fertilisers justify much 

 more latitude, however, and no good farmer ought 

 to be restricted in his cropping, provided, of course, 

 that he maintains the fertility of his land. It is 

 sometimes a convenience on the~ dairy farm to grow 

 the same crop year after year on the' same land, and 

 the Rothamsted experiments show that this can be 

 done, excepting only in the case of clover. With this 

 exception there is no more need to have a rotation of 

 crops than there is to have a rotation of tenants in a 

 house. It is essential, however, that the land should 

 be kept free from other competitors and from disease 

 germs. Freedom from competition means the exclusion 

 of weeds. In the old days this had to be effected by 

 periodical bare fallows. Nowadays a different course 

 is possible ; modern cultivation implements Avorked 

 by a tractor allow great scope for the suppression of 

 weeds. There is, however, one crop that must be 

 grown periodically to ensure the bes't results- clover 

 j or a mixture of clover and" grass. Clover affords valu- 

 j able food for cattle during winter, and it also en- 

 riches the soil in highly valuable nitrogenous organic 

 I matter. Much of this is the work of the plant itself, 

 I and could equally well be done by grass; but the 

 enrichment in nitrogen is the work of bacteria residing 



