62 BULLETIN 150, U. S. DEPARTMENT OF AGRICULTURE. 



doubted if the fertilizers of which they form a part were used in 

 very great amount. They are objectionable on the further score 

 that they render the material of which they form a part hygro- 

 scopic, which property in moist air causes the fertilizer to cake. 

 The ingredients of kelp other than potassic, it has been shown, are 

 salt and organic matter, the nitrogen of which, rated as ammonia, 

 adds materially to the market price of the product. The organic 

 matter itself is of value, as -contributing — to a small extent, to be 

 sure— to the organic constituents of the soil, known by the indefinite 

 term of " humus." 



PREPARATION OF DRY FERTILIZER FROM KELP. 



Since the ingredients of kelp are either neutral or beneficial in their 

 influence on plant growth, to prepare kelp for use as a fertilizer it 

 is necessary only to convert it into a form in which it can be pre- 

 served and shipped. To accomplish this it is sufficient to harvest, 

 drive off the water which it contains, and grind it to a coarse powder 

 for bagging and mixing. 



Kelp is being harvested by a machine which embodies the prin- 

 ciples of the mowing machine or reaper used in harvesting agricul- 

 tural products. The harvester actually in operation consists 

 essentially of a barge over the end of which projects an adjustable 

 frame, supporting an endless belt, tilted to form an inclined plane. 

 Across the lower end of the belt extends a horizontal cutting bar 

 about 10 feet in length, of the type used in the construction of reapers, 

 which is supplemented at each end by two perpendicular knives. By 

 this arrangement a swath may be cut through the kelp 10 feet in 

 width and of a depth determined by the adjustment of the supporting 

 frame. Back of the knives the belt, constructed of chains and 

 netting, is operated in such a way as to catch the severed kelp and 

 lift it upon the barge. Beneath the upper end of the belt is a 

 chopper into which the kelp drops and by which it is cut into short 

 lengths. From this it passes onto a short conveyor which loads it 

 into a large scow made fast alongside. The small barge carrying 

 the cutter is moved along the side of the large scow so that the load 

 of cut kelp is distributed evenly. To operate the moving parts of 

 the machine a gasoline engine is provided. The barge and scow 

 are pushed through the kelp groves by a launch, which serves also 

 to tow them to the dock for unloading. (PI. VI, fig. 2.) 



The cost of cutting will be determined by the conditions obtaining 

 at the place of cutting. The results obtained so far indicate that this 

 will be not more than 50 cents per raw ton, and easily may be reduced 

 to 25 cents or less, inclusive of unloading at the dock. 



It can not be expected that the cutter now in operation embodies 

 all the perfections to which such a machine is susceptible, nor that 



