SUCCESSION OF CROPS. 125 



vided with an extensive system of large and vigorous 

 leaves, calculated to cover the ground, foul the soil. 



The grains, from their slender stalks rising into the air, 

 and their long, narrow leaves, easily admit into their inter- 

 vals those weeds that grow upon the surface, which, being 

 defended from heat and winds, grow by favor of the grain 

 they injure. 



Herbaceous plants, on the contrary, which cover the 

 surface of the soil with their leaves, and raise their stalks to 

 only a moderate height, stifle all that endeavours to grow at 

 their roots, and the earth remains clean. It must be ob- 

 served, however, that this last is not the case unless the 

 soil be adapted to the plants, and contain a sufficient quan* 

 tity of manure to support them in a state of healthy and 

 vigorous vegetation : it is for want of these favorable cir- 

 cumstances that we often see these same plants languish- 

 ing, and allowing the growth of less delicate herbs, which 

 cause them to perish before their time. Vegetables sown 

 and cultivated in furrows, as are the various roots and the 

 greater part of the leguminous plants, allow room for a 

 large number of weeds ; but the soil can be easily kept 

 free by a frequent use of the hoe or weeding fork; and by 

 this means may be preserved rich enough for raising a 

 second crop, especially if the first be not allowed to go to 

 seed. 



The seeds that are committed to the ground ofterl con- 

 tain those of weeds amongst them, and too much care 

 cannot be taken to avoid this : it is more frequently the 

 case, however, that these are brought by the winds, depos- 

 ited by water, or sown with the manure of the farm-yard. 



The carelessness of those agriculturists who allow this 

 ties and other hurtful plants to remain in their fields, can- 

 not be too much censured; each year these plants produce 

 new seeds, thus exhausting the land and increasing their 

 own numbers, till it becomes almost impossible to free the 

 soil from them. This negligence is carried by some to 

 such an extent, that they will reap the grain all around the 

 thistles, and leave them standing at liberty to complete 

 their growth and fructification. How much better it would 

 be to cut those hurtful plants before they flower, and to add 

 them to the manure of the farm. From the principles 

 which I have just established, we may draw the following 

 condusions. 



11* 



