THE HAY- FIELD AND ENGLISH HAY. 175 



that purpose. The slowness of that process, in case of 

 naturally good grass lands, has concealed that result to such 

 an extent, apparently, that we cannot point out to-day the ex- 

 istence of a generally recognized more comprehensive sys- 

 tem of manuring permanent grass lands. We treat them 

 still quite largely without any well defined idea in regard 

 to the particular way of action of the substance we supply 

 for manurial purposes. A short discussion of some of the 

 more prominently mentioned manurial substances recom- 

 mended for use upon grass lands may illustrate that point. 



Common salt is known quite frequently to act beneficially 

 on grass lands ; it acts, however, more decidedly on the physi- 

 cal qualities of the soil than as a direct plant feeder ; it 

 assists in the absorption of moisture from the air and econo- 

 mizes inherent resources of moisture, and is thus apt to act 

 better on dry lands than on moist ones ; it assists in the dif- 

 fusion of potash and phosphoric acid, but does not materially 

 benefit the supply of the most essential article of plant food. 

 The beneficial effect usually ceases after a few applications 

 of from 400 to 500 pounds per acre ; the lands are more ex- 

 hausted after its exclusive use as manure than before. 



Gypsum, or plaster, has the reputation of assisting in 

 the absorption of the ammonium compounds of the air ; it 

 counteracts the tendency of a clayish soil to become hard 

 and impervious in dry weather ; it assists, like the salt, in the 

 general diff"usion of potash and phosporic acid present by 

 causing favorable transformations of existing compounds ; a 

 few repeated applications of from 600 to 700 pounds per 

 acre usually terminate its good services, which are fre- 

 quently marked rather by a more liberal growth of clover 

 and of leguminous plants in general than by that of grasses. 

 Aside from lime and sulphuric acid, nothing is added to the 

 future fitness of the soil, as far as essential articles of soil 

 plant food are concerned. Gypsum, as the sole manurial 

 matter used on grass lands, assists in bringing nearer the 

 time of their failure as a remunerative fodder source. 



Air-slaked lime, lime-kiln ashes and various other kinds 

 of lime refuse, are noted for their frequent good influence 

 on grass lands ; they assist in producing a favorable compo- 

 sition of organic matter and aid in the disintegration of 



