Farmyard Manure. 



[JUNE, 



great accumulation of nitrogenous material in the soil. How 

 great the waste may become is seen by comparing the nitrogen 

 supplied to one of the permanent wheat plots at Rothamsted, 

 which receives 14 tons of farmyard manure per acre every 

 year, with the nitrogen stored up in the soil and that removed 

 in the crop. Table XI shows that only 26 per cent, was re- 

 covered in 50 years, and that nearly 57 per cent, has been lost, 

 since it is accounted for neither in the crop nor in the soil at 

 the end of the period. 



Table XI. 



Plot. 



Manuring. 



Nitrogen in Soil 

 9 inches deep, 

 1893. 



mate Supply 

 itrogen in 

 : in 50 Years. 



£ O g ^2 



of Nitrogen 

 'lot 3, un- 

 :ed for in 

 • Soil. 







' Per 

 Cent. 



Pounds 

 per Acre. 



Approxi; 

 of N 

 Manure 



slu i 



Cu 0 00 

 a, g C - 

 < 



Surplus 

 over 1 

 accounl 

 Crop oi 



3 

 2 



Unmanured 

 Farmyard manure 



0-0992 

 0*2207 



2-570 

 5*i50 



Lb. 

 10,000 



Lb. 



850 

 2,600 



Lb. 

 5>67o 



These, however, are extreme cases ; on referring to the crops 

 grown with the rich and poor dung on p. 162, where four 

 crops in rotation are grown after each application of farmyard 

 manure, out of 207 lb. of nitrogen supplied as dung made from 

 roots and hay alone 144 lb. were recovered in the three following 

 years, and of 257 lb. supplied as cake-fed dung 158 lb. were 

 similarly recovered. 



The extremely lasting character of those nitrogenous com- 

 pounds in farmyard manure which are not recovered in the 

 first year or two is illustrated in an exceptional manner in 

 the Rothamsted experiments. On the grass land, for example, 

 one plot received 14 tons of dung per acre per annum for 

 eight years (1856-63) and then was left unmanured. Table XII 

 shows that it has continued to give a larger crop than the 

 unmanured plot alongside for more than 40 years. The table 

 shows that in the year the application of farmyard manure 

 was stopped the plot with the residues of the previous eight 

 years manuring gave double the yield of the unmanured plot, 

 in the following year the 3 7 ield was still double, but from that 

 time its superiority has slowly declined, though for the last 

 10 years it has still amounted to 15 per cent. 



