88 The Principles of Fruit-growing 



lands that are comparatively free from stones and rubbish. 

 The plow-like action of its blades serves to pulverize the 

 soil, to spread the mulch evenly, and it leaves a most 

 excellent seed-bed. 



The cutaway or disc-harrows may be either beneficial 

 or positively injurious. If the discs are so set that they 

 cover but a part of the surface with the mulch, they leave 

 a ridge exposed to the action of the wind and sun, and the 

 rate of evaporation is greatly increased. The discs should 

 be set at such an angle that the whole surface shall be 

 stirred or covered. Their chief value lies in the cutting 

 and pulverizing action on clay soils, but as conservers of 

 moisture they are inferior to the Acme or the spring- 

 tooth. Soils that need the disc-harrow to pulverize them 

 should usually be gone over again with some shallower 

 tool. 



The mellower the soil, the lighter should be the work 

 done by the harrow. On most heavy orchard soils, it will 

 be found necessary to use the heavy tools, like the spring- 

 tooth and disc-harrows, in the spring, but if the land is 

 properly handled it should be in such condition as to 

 allow the use of a spike-tooth or smoothing-harrow in 

 summer. This light summer harrowing should be sufficient 

 to keep down the weeds, and it preserves the soil-mulch in 

 most excellent condition. With such a tool and on land 

 in good tilth, a man can harrow 10 or more acres a day. 



Cultivators and moisture-saving. 



The action of cultivators is not materially different 

 from that of the spring-tooth harrow. The size of the teeth 

 should be regulated by the work to be performed, an imple- 

 ment with many small teeth being preferable to one with 

 a few large teeth when the object is to conserve moisture. 



