552 NATUBE AND PEOPERTIBS OF SOILS 



The effect of lime on nitrification is very noticeable in June. 

 In April the no-lime plats are higher in accumulated nitrates, 

 due to the lesser growth of the green-manuring crop. 



317. Practical utilization of green-manures.— Green- 

 manures seem to have their greatest value where a permanent 

 instead of a rotation pasture is used, where a long cycle rota- 

 tion of grain is practiced, or where little or no manure is 

 available. The experimental data bearing on the use of green- 

 manures seems to indicate that such a practice is productive 

 of larger crop yields. The following data from Nappan, Nova 

 Scotia, is from one of the more reliable and conclusive experi- 

 ments. A catch-crop of clover in the grain was turned under 

 for grain the following year. The figures are for 1905, the 

 third year oi the test. 



Table CXXVII 



yield of wheat, oats and barley in bushels to the acre 



on the nappan farm in 1905 on plats cropped 



continuously to grain.^ 



Treatment 



Wheat 



Oats 



Baelet 



No srreen-manure 



34.3 

 40.0 



41.2 

 55.3 



32.7 



Clover catch-crop 



37.9 



The use of a green-manure is often determined by the char- 

 acter of the rotation. Very often it is somewhat of a problem 

 as to wlien, in an ordinary rotation, a green-manure may be 

 introduced so that it may fit in well with the crops. In a 

 rotation of maize or potatoes, oats, wheat, and two years of 

 hay, a green-manure might be introduced after the corn or 

 potatoes. This would not be a very good practice, however, as 

 a cultivated crop usually should follow a green-manure in 

 order to facilitate decomposition and decay. In such a rota- 

 tion, the plowing-under of the hay stubble is really a form 



* Ottawa Exp, Farms Eept., 1905, p. 284. 



