76 THE PRINCIPLES OF AGRICULTURE 



97a. The subsoil plow does not turn a furrow (Fig, 23). It 

 is drawn by an extra team, which follows the ordinary plowing. 



99a. A useful tool for making and maintaining the soil -mulch 

 is the smoothing harrow shown in Fig. 24. On hard lands, 

 however, heavier and more vigorous tools must be used. 



99/>. Observe how moist the soil is in forests, even in dry 

 times. This condition is due partly to the forest shade, but ' 

 perhaps chiefly to the mulch of leaves on the ground (Fig. 25). 



101a. Some farmers are always asking how to kill weeds, as 

 if this were the chief end of farming. But good farmers seldom 

 worry about weeds, because that management of the farm which 

 makes land the most productive is also the one which prevents 

 weeds from gaining a foothold. But there are some cases, as 

 we shall find in the next chapter, in which weeds may be 

 allowed to grow with profit. 



102o. A planker or float is shown in Fig. 27. This is a 

 home-made device. In some parts of the country it is called a 

 slicker ; and in the West it is known as a drag. In the East, the 

 word drag is synonymous with harrow. 



104a. To determine when and how much to roll land, is one 

 of the most difficult of agricultural operations. This is because 

 the good effects are so often followed by the ill effects of loss 

 of moisture and of puddling of hard lands when heavy rains 

 follow. Whenever the object of rolling is to compact loose 

 lands or merely to crush the clods, the work should be quickly 

 followed by the harrow or cultivator. Compare Figs. 28 and 29. 



