78 The Control of the Soil [pt. ii 



weeds, which has to be done by uprooting them and 

 leaving them on the surface to perish for want of water, 

 or, in the case of annuals, burying them deeply enough 

 to prevent their springing up. Weed seeds unfortunately 

 cannot be killed in this way, but must be encouraged to 

 germinate; the young seedlings are then uprooted. This 

 process is called "cleaning" the land. 



Winter cultivation . As soon as possible after the com 

 is cut, and if necessary before it is carted, a broadshare 

 should be sent over the land to skim off the surface and 

 leave it to dry. Weeds and grass are thus killed, but the 

 ground below remains moist enough to afford weed 

 seeds a chance of germinating. Winter ploughing can 

 then be begun when convenient. 



On heavy lands the earlier this is done the better. 

 The special objects here are to ensure that the land shall 

 dry quickly in spring and that the clay shall take on 

 the proper crumbly condition. The former is secured 

 by leaving the land in a rough state so that a consider- 

 able surface is exposed, and also by arranging that water 

 can easily get away. The latter is effected by a combina- 

 tion of good cultivation with the addition of lime, chalk 

 or limestone, and of organic matter, and by exposure to 

 frost. On the other hand long exposure to water {e.g., a 

 long wet winter), alkaline substances such as liquid 

 manure, large excess of certain fertilisers, and general 

 bad management, all tend to change the crumbly into 

 the undesirable sticky state. 



On light, sandy or peaty land it is not necessary to 

 start so soon : the main object is to kill weeds, and delay 

 is permissible so long as no seeding takes place. 



The process of cultivation is carried out first by 

 ploughing, then by harrowing and rolling. It is not our 



