August, 1910.] 



133 



Scientific Agriculture. 



without any necessity for importing 

 nitrogen. The natural agencies of 

 nitrogen fixation due to the growth of 

 the clover crop and the bacteria depend- 

 ing on the supply oxidisable carbon- 

 aceous 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 laud the potash 

 and calcium carbonate will be furnished 

 by the soil, while 4-5 cwt. of superphos- 

 phate per acre for the roots will main- 

 tain or even increase the stock of 

 phosphoric acid. 



The 4 qr. of wheat per acre level 

 of production is, however, a low one to 

 aim at ; although it is the actual aver- 

 age production of the country at the 

 present time, it is below that which a 

 good farmer expects to-day, and must, 

 indeed, attain if he is to make a satis- 

 factory profit on his land, But if the 

 general level of production 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 

 required, either in the form of nitro- 

 genous fertilisers for the root and wheat 

 crops or of purchased feeding-stuffs to 

 enrich the dung. Nor will it be suffi- 

 cient, and this is a very important point, 

 merely to add as much nitrogen as is 

 taken away from the land in the increas- 

 ed 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 hew 

 great the wastage becomes when a large 

 amount of dung is put on the land every 

 year, aud 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 addi- 

 tion of manure produces the best effect ; 

 each succeeding application produces 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 posi- 

 tion of equilibrium will be reached 

 (viewed over a term of years long 

 enough to smooth out seasonal effects) 

 when the natural recuperative agencies 

 and the additions of fertilisng material 

 in the manner are balanced by the re- 

 movals iu crops and stock and the inevi- 

 table waste, The higher the level of 

 production, the greater will be the 

 waste, and, in consequence, the addi- 

 tions of fertiliser must be doubly in- 

 creased to maintain the balance. How 

 high a level of production can be profit- 

 ably maintained is determined by the 

 prices that rule for the crops, but there 

 will always come a limit when the produc- 

 tion can be no longer increased by addi- 

 tions of fertiliser except at a loss ; at 

 such a stage it is only the introduction 

 of improved varieties or some variation 

 in the methods of cultivation inducing 

 a better utilisation of the fertiliser which 

 will still profitably increase the produc- 

 tion per acre. 



On examining the variations in farm- 

 ing systems iu different parts of the 

 country, it will be found that farmers 

 do instinctively adapt their expenditure 

 on fertilisers (including feeding stuffs), 

 and, therefore, their level of production 

 to the maguitude of the returns they 

 can get for their produce ; one man will 

 have a large cake bill and spend 40s. per 

 acre on artificial fertilisers during his 

 rotation ; he can maintain a high level 

 of condition, and therefore of waste 

 in his soil, because he can get good 

 prices for potatoes, or barley, or sheep, 

 whatever his staple product may be. 

 But on poorer land and with less suit- 

 able markets a man may be driven to 

 cut down his cake bill and spend only 

 10s. per acre on fertilisers, because his 

 products are not valuable enough to 

 compensate for the waste at the higher 

 level of condition in the land. Thus the 

 problem of what is a profitable manure 

 for a given crop becomes a very complex 

 one, and the biggest factor is perhaps 

 the level of production at which the 

 individual farmer can conduct his busi- 

 ness remuneratively. 



