40 



alone proves so largely beneficial to grasses, to depend ex- 

 clusively npon this material. It should be clearly under- 

 stood that nitrate supplies but one of the more important 

 elements of plant food, and that continued dependence upon 

 such one-sided manuring must therefore be unwise. 



On the grounds of the Agricultural College is a plot of 

 land containing about one-half acre, which for the last five 

 or six years has been annually top-dressed with nitrate of 

 soda alone. The mowing is one which has not been broken 

 up for at least twenty years, and the prevailing species is 

 Kentucky blue-grass. The product at the present time is 

 exceedingly unsatisfactory. The grass during its growth 

 shows a rather deep bluish-green color. Its growth is short, 

 and it seems peculiarly liable to rust. Adjoining land of 

 similar character, which six years ago was in the same con- 

 dition as this half-acre, and which has been top-dressed with 

 potash salts and slag meal in combination with nitrate, pro- 

 duces far heavier and more satisfactory crops. Nitrate alone, 

 therefore, should be used for the grass crop only under ex- 

 ceptional conditions, and then not for many consecutive years. 

 Two years will in most cases probably be the limit. 



The Possibilities of the Hay Crop without Manures or 

 Fertilizers supplying Nitrogen. — The fact that good crops 

 of clover can be produced on land Avliich for many successive 

 years has received applications of materials furnishing of 

 the different important plant food elements only phosphoric 

 acid, potash and lime, was pointed out in the first paper upon 

 this subject. In that paper the ability of clover to thrive on 

 soils thus treated, due to the fact that it can take the needed 

 nitrogen from the air, was especially emphasized. Attention 

 is now called to the fact that good crops of mixed hay (clover^ 

 and grasses) can be produced under this system of manuring. 

 A striking evidence of this fact is afi^orded by a number of 

 plots on the grounds of the Massachusetts Agricultural Col- 

 lege. It can readily be understood how good crops of clovers 

 are possible under this system. It will not be equally clear, 

 ]->erhaps, to all how grasses which are known to take all the 

 nitrogen which they require from the soil can thrive on soils 

 to which for a long series of years neither manure nor fer- 



