Tilth and Tillage of the Soil 1769 



to the solid disk. On hard soil the disk plow is more efficient than the 

 moldboard plow for the draft consumed. 



Subsoiling. — Subsoiling is the operation of breaking up the subsoil 

 without turning it to the surface. A special plow is used in the bottom 

 of the furrow behind the turning plow. (Fig. 94.) Subsoiling is practiced 

 most safely in the fall. Unsatisfactory results are likely to follow sub- 

 soiling in the spring. 



Deep tilling implements. — An intermediate implement between the 

 turning plow and the subsoil plow is the Spalding Deep Tilling machine. 

 (Fig. 94.) This is of the solid disk type. There are two disks, one behind 

 and below the other. They are carried on a sulky frame, and by proper 

 adjustment the soil can be worked twelve to sixteen inches deep. Its 

 use appears to be relatively more safe than would be plowing with the 

 moldboard plow to the same depth, for, although the subsoil is stirred, it 

 is only partly thrown to the surface and mixed with the topsoil. In order 

 to accomplish the mixing of the right proportions of subsoil with the soil, 

 special attention must be given to the relative amount of cutting done by 

 the two disks. 



Double sulky plow. — The use of the double sulky plow is increasing 

 rapidly. This implement carries two plows, one a right-hand and the 

 other a left-hand pattern, so that all the cutting is done from one side. 

 Dead furrows and back furrows, both of which render the crop uneven, 

 are thus eliminated. Sulky plows, owing to their weight, are not suited 

 to uneven land where it is necessary to pull up the slope. 



Cultivation 



After plowing, the soil should usually be worked down and pulverized 

 at once. At that time the lumps are most easily pulverized , and by level- 

 ing and fining the surface moisture is saved. In the case of fall plow- 

 ing this practice is not recommended, as the rough surface holds the 

 snow during the winter and is less subject to puddling during the spring 

 thaws. Cultivators stir the soil. For rapid work some type of harrow is 

 generally used. 



Harrow. — The harrow is a broad, many-toothed implement, generally 

 without wheels or guiding handles. There are three main types of harrows : 

 the spike-tooth, the spring-tooth, and the disk. (Fig. 98.) The spike-tooth 

 harrow is light, and is therefore suited to rather clean soil in fairly good 

 condition. The spring-tooth harrow draws to the ground better than does 

 the spike- tooth harrow. It works to greater depth and tends to bring lumps 

 and stones to the surface and to collect roots and vines. Usually the slant 

 of the teeth of spike- and spring-tooth implements can be readily adjusted, 

 and this determines the extent to which they stir the soil. The weeder 



