RELATION OF YIKLD TO X1T1;()( IFA SI riM \ KM 



of crop is somewhat (lepeii<k>iit on tlie source of nitrogen 

 employed: thus I Ih. of nitrogen as animonium-sahs gives un 

 increase of 01 10 ton, as nitrate of soila the increase is 0147 



ton fov each lb. of nitroi^'en, while with rape cake the increase 



WITH COMPLETE MlNEKAl.s. 

 (Plots 4.) 



WITH l)LX(i. 

 (P1.0TH 1.) 



Fill. 14. — Maiifrtl Wur/.el. KfTict of iiureasiiif; ainoimts of Nitrop n. Avini;.'c 

 Produce of Roots per acre. 1 876-1 W2. 



O = No Nitrogenous Manure. I N = S(5 II). Nitrogen as Nitrate of Stnlii. 



A = 86 lb. Nitrogen as Ainmoniuin-salts. I C = 9S lb. Nitrogen as Ha|>o Cake 

 AC - P-^ lb. Nitrogen as Rape Cake, and *"') Ih. Nitn>;,'<'n as ,\mnioniiiin-salts. 



is 0T03 ton for each II). of nitrogen api)lic(l. IJape cake, in fact, 

 is not strictly comparable with the other two sources of 

 nitrogen, for not only does it contribute a consideiable aniouni 

 of organic matter to t):e soil, thus improving its texttuc arnl 

 water-retaining power, l»ut it is also a more .sl.)wly-aeting 

 manure. Some of its residues accumulate from .sea.son to 

 sea.son, and little by little become available for ihe later crops, 

 while we have plenty of evidence that, on the liothamsted soil. 



