6 BOARD OF AGRICULTURE. 



Now, suppose the owner keeps this land for pasture, waging 

 a war against the weeds and encouraging the growth of more 

 desirable species of grasses. Cattle eat off the herbage and 

 leave their droppings upon the surface, much of foliage dies 

 each yeaiydccays, and is mingled with the mere surface soil, 

 and slowly but surely the vegetable matter increases there. 

 The annual crop is drawn largely from the air, and that which 

 is left on the ground does not go back to its original elements 

 quickly, and thus it is that the vegetable matter increases, 

 and especially at and near the surface. But the mineral ele- 

 ments in the soil are also changing, partly from the effects of 

 the air, moisture, heat and cold, and partly from the action 

 of the vegetation itself, one crop of which gets some into a 

 soluble condition which was before unavailable, and as the 

 plant decays, this mineral portion is in fit condition to be used 

 by the next growth. 



A change in the texture of the turf goes along with these, 

 the roots gradually form a firmer mat in the soil, the foliage 

 a denser growth above it. The number of individual plants 

 on a given space increases. At first the separate plants were 

 scattered and covered but a small portion of the soil, but they 

 gradually occupy more and more of the soil, and the bare 

 spaces grow fewer and smaller. But this is accompanied by 

 still another change, that of the species themselves. Those 

 species that find the best conditions of their growth, get pos- 

 session, and gradually crowd out those that are not quite so 

 completely at home under the same conditions. As tke soil 

 has been changing, the species growing upon it have been 

 changing. I do not mean that one species is changing into 

 another, but that one supplants or runs out another. The 

 wiry and tough grasses we began with, have been yearly grow- 

 ing less as the soil became richer and the better species had 

 a chance to thrive, for these better kinds will run out the 

 poorer, if the soil is right and they are encouraged. 



There has been a change of species, and also a larger num- 

 ber of kinds has come in, because the soil will support a mix- 

 lure of species better than any one of them alone. This is a 

 rule in nature, as well as in farming. Our forests consist of 



