148 SOILS 



The spring-tooth harrow is a good implement 

 for rough work, and especially for stony ground. 

 It is very popular for orchard tillage, partly be- 

 cause the teeth spring over the roots with little 

 damage to them. It is not so serviceable when sod, 



^5 



freen manure, or a large quantity of strawy manure 

 as been plowed under, as the teeth are likely to 

 dig out part of this material and leave it on the 

 surface. 



On rough land the spring-tooth harrow is jerky 

 and hard upon the horses' shoulders. The draft 

 of a spring-tooth harrow set moderately deep is 

 about equal to the draft in plowing, but it is easier 

 for a team to plow all day than to pull a spring- 

 tooth harrow all day, because the plow runs more 

 evenly. The jerkiness of the common type of 

 this harrow in which all the weight rests upon the 

 teeth is largely overcome in a more recent form, 

 which is mounted on wheels. All the weight of 

 this implement rests upon the wheels, thus allow- 

 ing the teeth to pull up and loosen the soil, and re- 

 lieving somewhat the unevenness in draft. Even 

 the common type of spring-tooth harrow, however, 

 leaves the soil lighter than most other harrows 

 because of the upward pull of the teeth. It is this 

 advantage, as well as durability and the ease with 

 which obstructions are cleared, that makes the 

 spring-tooth harrow so popular. It can be bought 

 by sections in various sizes; the wider it is, within 

 reasonable limits, the cheaper will the harrowing 

 be done. 



Acme Harrow. This is the most noted repre- 

 sentative of a type of implements known as the 

 coulter harrows, so called (because they have teeth 

 that have been twisted, somewhat resembling a 

 plow coulter. The teeth first cut the soil, 



