TEMPORARY PASTURES. 363 



from lifting after tliev have been ploiiglied up is, in 

 some instances, felt for at least three years. 



While the grasses proper do not, like clovers, ad<l 

 in the same way to plant food in the soil, they do add 

 materially to the snpj)ly of available plant food. Dur- 

 ing the processes of gro^^'th they search out and take 

 up plant food from the soil and subsoil, a part of which 

 is retained in the roots broken up and in the stubbles 

 that are buried. These, in their decay, furnish such 

 food for the crops that follow them in a form that is 

 easily accessible. The grass crops, in a sense, act the 

 part of scavengers in the soil for the crops that come 

 after them. Sir J. B. Lawes has estimated that when 

 grass lands are broken 5 to 10 tons of dry matter, roots, 

 leaves and stulibles are deposited in one acre l)y the gTass 

 crop. 



Grass crops check the growth of weeds in the soil in 

 various ways. In some instances they crowd them out, 

 as in the case of blue grass ; in some, as when mowed 

 and properly pastured, they prevent them from seed- 

 ing; and in others, as when they are broken for a few 

 years, they cause the seeds of many weeds to perish 

 that are lying in the soils. Pastures and meadows of 

 any lengthened duration render most effective service 

 in this way, as is evidenced by their comparative clean- 

 liness when first broken up. 



So beneficent are the influences from introducing 

 grass crops frequently into the rotation, that it is 

 probably correct to say that the instances are few in 

 which successful crop husbandry can be long conducted 

 in their absence. Due attention to this quo-^ion would 

 Grasses — 24. 



