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of oxidisable carbonaceous matter returned to the soil are capable 

 of restoring sufficient nitrogen to the land to balance such an 

 output and to repair other unavoidable waste. Of course, such a 

 conclusion deals with nitrogen alone; it assumes that the supply 

 of phosphoric acid, potash, and calcium carbonate is adequate, and, 

 indeed, on much British land the potash and calcium carbonate 

 will be furnished by the soil, while 4-5 cwt of supeiphosphate per 

 acre for the roots will maintain or even increase the stock of 

 phosphoric acid (i). 



The 4 qr. of wheat per acre level of production is, however, 

 a low one to aim at; although it is the actual average production 

 of the country at the present time, it is below that which a good 

 farmer expects today, and must, indeed, attain if he is to make a 

 satisfactory profit on his land. But if the general level of pro- 

 duction is to be raised from the 4 qr. of wheat to, say, the 5 qr. 

 of wheat standard, then an external supply of nitrogen will be re- 

 quired, either in the form of nitrogenous fertilisers for the root 

 and wheat crops, or of purchased feeding-stuffs to enrich the dung. 

 Nor will it be sufficient, and this a very important point, merely 

 to add as much nitrogen as is taken away from the land in the 

 increased corn crops ; we have to add enough to get the land into 

 much higher condition, and this means greater wastage at every 

 stage- We have seen in the case of the Rothamsted plot receiving 

 dung how great the wastage becomes when a large amount of dung 

 is put on the land every year, and though the losses in this case 

 are excessive, they will always become greater at an ever-increasing 

 ratio the higher the condition of the land. It is another example 

 of the well-known law of diminishing returns ; the first addition of 

 manure produces the best effect ; each succeeding application pro- 

 duces a smaller increase in the crop till at a certain point nothing 

 further is gained, however much manure is put on. 



We may conclude, then, that with every system of farming a 

 certain position of equilibrium will be reached (viewed over a term 

 of years long enough to smooth out seasonal effects) when the na- 

 tural recuperative agencies and the additions of fertilising material 

 in the manure are balanced by the removals in crops and stock 



(i) A production of 4 quarters of wheat per acre, i. e. 32 bushels, cor- 

 responds to 28.8 hectolitres per hectare. Aiming at a standard of 5 quarters 

 per acre corresponds to raising the average production to 36 hectolitres per 

 hectare. Ed. 



