1234 AGRICULTURE. BOOK I. 



2. The destruction of weeds. — Weeds may be divided 

 into two classes ; those which spring up annually, and those 

 which are perennial. The former are destroyed in broadcast crops 

 of corn, and in naked fallows, &c. by harrowing when they appear 

 alive on the surface ; or in drilled crops by hoeing', either with 

 the hand or horse-hoe. The latter are chiefly destroyed by fal- 

 lowing, either partially, as in the preparation for potatoes, bar- 

 ley, turnips, &c. ; or completely, as in naked or summer fallows. 

 In this part of cultivation, much depends upon knowing the 

 nature of the weeds to be destroyed, and much upon our pre- 

 venting them from coming into seed. There are some seeds 

 which, although buried under ground for many years, do still 

 germinate where brought within a certain distance from the 

 surface ; such as avena communis (wild oats), the rhaphanis rapha- 

 nistiam, and r. vulgaris, which are very common weeds. A 

 field that has been infested with these all the summer, will have 

 its surface covered with their seed at harvest ; if the ground be 

 ploughed soon after, the seed will be preserved in the soil foryears; 

 but if it be allowed to remain until spring, and then gently har- 

 rowed, the whole will vegetate, and may easily be destroyed. 

 In this way all seeds of weeds could be rendered ineffectual ; 

 though it is not always consistent with the general management 

 of a farm, as it throws the labour behind, and prevents the land 

 from deriving the advantage of the winter's frosts, &c. One 

 field, however, managed in this manner each year, would soon 



