NITROGEN GAINKT) OIJ LOST 



*J()9 



V. Gain or Loss ok Manuhial Constitiknts to rm I, am.. 



From the analyses wliich have been uuulc from time to 

 time of the crops on A^dell Held it is ])ossil)l(' to estimate tlic 

 quantities of the chief manurial ingredients m'trogcn, jdios- 

 plioric acid, and potash \vhich arc removed from llic snil 

 (hn'ini;' a typical rotation. Thus we can form some iiliM (.f 

 what will be necessary to maintain tlie fertiHty of land midn- 

 ordinary crop, and whether there are any natural n-ciipcialivc 

 agencies which restore plant food to the soil. 



Table LXXIII. shows the amount of nirro,i;en removed per 

 acre per annum on the three plots whieli are fallowed and 

 where also the roots are carted off where every thinu is, in 

 fact, removed, and no nitrogen is added except in the one case 

 on Plot C where the Swedes are manured. 



Table LXXIII. — Nitroycn removed hy CroiJS r/roivn in rotation, Aiidill Fir/d. 

 Average of eight Courses, 1852-1883 Boots carted. 



It will be seen that on the unmanured [)lol> llie reiii(»\al (»f 

 nitrogen is chiefly effected l)y the two cereal eroi)s, so small 

 has the crop of roots become. The average !'>>> iA' nitrogen 

 over the whole four years of the rotation amounts to just 

 over 19 11). per acre per annum, wliich agrees very closely 

 with the average annual ivnioNal of niti-ogeii from the 

 unmanm-ed plot in Broadbalk where wheal is giown yeai- 

 after year. When mineral manures ai'e used for the Swedes 



