122 CHAPTER VIII 



use the latter plough. In open loose soils the disc ploughs are inferior 

 to the other type. By the use of two discs inclined towards each other, 

 they may be used for furrowing, and they also find one of their most extended 

 uses in turning over and burying the pea vines grown as a green manure. 



Knife Plough. Fig. 30 shows an implement used to some extent in the 

 Hawaiian Islands as a substitute for the ordinary turn plough. It is used 

 in connection with steam tackles in preparing the land for planting, and 

 does not turn over the soil or make a furrow. Its action is to break up and 

 loosen the .soil to a depth of about two feet. 



The Cultivator. The cultivator, which has developed from the shovel 

 plough or horse hoe, is shown in Fig. 31. In cane fields this instrument is 

 drawn by animal power between the rows of cane, breaking up the soil and 

 destroying the weeds. The disc cultivator is shown in Fig. 32. It is built 

 to straddle the row, the discs being set to throw dirt on the row. These 

 instruments can only be used on young cane, and when the crop is too far 

 advanced to permit their use it is said to be laid by. 





FIG. 33 



The Harrow. This implement, a form of which is shown in Fig. 33, is 

 used after ploughing and before making the furrow to break up the clods of 

 earth. The action of the harrow may be supplemented by the use of rollers. 

 The principle of the disc has also been applied to the harrow, and a form of 

 disc harrow is shown on Plate XIV. This appliance is used in the Hawaiian 

 Islands to cut up cane trash and green manures before turning them under 

 with the plough. 



Special Cane Implements. In Figs. 34, 35 and 36 is shown the Benicia- 

 Horner No. I Ratoon and Cane Disc plough, which has found an extended 

 use in the Hawaiian Islands. It contains in detachable parts a double 

 mould-board plough, a revolving knife, right and left-hand discs, and a sub- 

 soil plough ; it may be used as a furrower, either for planting or for irrigation, 

 for bursting out middles, as a cultivator for throwing soil on to the cane row 

 or with the object of hilling up the latter, for trimming and subsoiling the 

 sides of the cane row, and slicing and cutting the ratoon row. 



When used as a furrower (Fig. 36) for planting or irrigation, the imple- 

 ment is equipped with both right and left-hand discs, with the double 

 mould plough and with the subsoiler ; when used to slice up ratoon cane 

 (Fig. 35) the plough is replaced by a revolving knife ; when used for 



