PROF. BREWER'S LECTURE. 7 



many kinds of trees and bushes intermingled. Any piece of 

 land left to itself will soon be clothed with a vegetation con- 

 sisting of many kinds, and you all know that if we wish to 

 grow any one species exclusively, on a given piece of ground, 

 we must take especial pains to keep the others off. We fight 

 weeds, we cut, pull, hoe, plow and wage war generally against 

 them, and yet they will get in, despite all this warfare. Fur- 

 thermore, if we grow any one kind in successive crops, for 

 example, successive crops of wheat, or corn, or tobacco, or any 

 one crop year after year, the soil is sooner exhausted than if 

 we pursue a rotation. So with any pasture, only there the 

 struggle is (or at least should be) between different kinds of 

 grasses ; and on any soil two or more plants of different kinds 

 close together will grow with more vigor than the same num- 

 ber of individuals of different kinds. On a given square yard, 

 for example, a greater weight can be grown if there are seve- 

 ral species mingled, than if there is but one, and moreover 

 this mixed forage is more eagerly eaten by stock, and is also 

 more nutritious. 



Now in an old pasture, the turf is made up of a variety of 

 species, closely intermingled, and this variety makes better 

 forage than any one kind would. If you have never tried it, 

 you will be surprised if you closely examine an old sod, to 

 see how many species go to make it. The nicest turfs have 

 generally quite a variety, and if you do not find such a variety, 

 then it is well to try to produce it, by sowing a variety of seeds, 

 and by manuring and other means, strive to coax them in. 



In pastures newly seeded, we commonly sec but one or two 

 kinds of grass-seed sown. Observing and thrifty farmers 

 often use three or four, but seldom more, yet in an especially 

 good old pasture, we often find two or three times the latter 

 number, some springing up earlier in the Spring, others hold- 

 ing on later in the Fall, and all striving together for room 

 during the Summer. This number of species is an important 

 element among the causes of the firmer turf of such old pas- 

 tures. If we closely examine a new pasture, even if well seed- 

 ed with one or two kinds of grass, we will find the ground by 

 no means all covered. There are bare spots between the 



