MANURING IN THEORY AND PRACTICE. 



349 



ordinary increase of growth made bj' the Hyacinth 

 so treated. The same effect wiU. he produced if 

 plants which are cultivated in pots are watered with 

 thin stale glue- water. But the nitrogen must first 

 he set free by fermentation and decay; for this 

 reason glue operates less hriskly if applied in an un- 

 decomposed condition. 



The increased product stimulated by nitrogenous 

 manures is necessarily attended with an increased 

 demand on the inorganic resources of the soil. It 

 must be remembered, therefore, that the constant 

 use of manures containing a large proportion of 



Sffect of Manure on Grass Land.— Our 

 meadows, lawns, and pleasure-grounds comprise, as 

 is generally known, not only a great number of genera, 

 and species belonging to the natural order Gramini(e, 

 but also various members of other families of plants, 

 among which far the most valuable in a pasture cer- 

 tainly is the Leguminous, or Clover and Vetchling 

 tribe. Thus in our meadows, lawns, and pleasure- 

 grounds there are associated members of almost every 

 family of plants that make up the crops of the garden. 



Experiments at Eothamsted on permanent meadow 

 land show that there is a considerable range in the 



Effect of Potash on the Tike. 



nitrogen, without a sufiScient supply of the mineral 

 or ash constituents of plants, may for a time increase 

 the yield, but the end will be exhaustion of the 

 available mineral food. Experience shows, however, 

 that the stores of available nitrogen within the soil 

 are sooner exhausted and brought down to an annual 

 minimimi than those of the minerals. 



A given amount of nitrogen as nitrate of sodium 

 usually yields more produce than an equivalent of 

 ammonium salts, and especially is this found to he the 

 case in dry seasons. This fact is due to the greater 

 solubility of the nitrate, or its products of decomposi- 

 tion, to their action on the subsoil disintegrating and 

 rendering it more porous; thus affording a larger 

 surface for the absorption and retention of moisture 

 and manure and greater permeability to the roots, 

 rendering the plants less dependent on the fall of 

 rain during growth. 



amount of produce yielded as hay by the various 

 plots according to the character of numure employed. 

 And with these great vsiriations in the bulb of pro- 

 duce obtained, it is found that there is also a most 

 striking difference in the botanical composition of 

 the mixed herbage. 



In the produce grown continuously without any 

 manure, the average number of species found has- 

 been 49. Of these, 17 are Grasses, 4 belong to the 

 order Legmninosee, and 28 to other orders. The per- 

 centage by weight of the Grasses has averaged about 

 68, that of the Leguminoste about 9, smd that of 

 species of other orders about 23 per cent. 



In the produce of the plot the most heavily 

 manured, and yielding the largest total crops, the 

 average number of species found has been 19 only, 

 of which 13 were Grasses, and 6 only of other plants ; 

 whilst the average proportions by weight have been 



