FERTILIZERS. 



835 



Total and available fertilizing constituents in Havmian soils. 



It is estimated fmiii analyses reported that a crop of cane prodncing 5 tonn of .sugar 

 per a(;re requires 15S.7 l!)s. of lime, 509.2 ll)s. nf potash, 74 lbs. of phosphoric- aiud, 

 and 164.7 lbs. of nitrogen. On tills basis it appears that lime is the only ingredient 

 present in the soil in suflicient quantity for the needs of the crop. Potash and phos- 

 phoric acid are much too low. 



To determine the relative retentive power for fertilizers and water of the so-called 

 "sandy soils," consisting mainly of fine coral particles, four of these soils " varying 

 in their proportions of lime carbonate from 71.25 per ci-nt to 91.07 per cent were 

 placed in iron pipes 2 ft. 6 in. long and 1 in. in diameter, the pipes being filled to 

 within 6 in. of the top. One gram each of amonium sulphate, nitrate of soda, and 

 muriate of potash were dissolved in a liter of water and 500 cc. of this solution hold- 

 ing 2' gin. each of tlie salts mentioned "were poured upon the soils and allowed to 

 drain through. It was foun<l in regard to the nitrate of soda that practically none 

 was retained by any of the soils, while the other compounds were fixed in an inverse 

 proportion to the lime carbonate content of the medium through which they 

 filtered. . . . When the nitrate is lost from the land through the over-saturation of 

 its soil, not only so much nitrogen is lost, but likewise a large amount of lime. . . . 



"To observe the action of nitrate on lime, as well as the relative action of different 

 salts in the same particular, tests were made at the experiment station in connection 

 with other lysimeter investigations. Nitrate of soda, chlorid of potash, ammonium 

 sulphate, and sulpliate of potash were applied to the rows of cane growing over the 

 lysimeter drains, and 48 hours later these rows were irrigated with 102 gal. of water, 

 of which quantity 33 gal. leached out and was analyzed," with the following results: 



Lime in drainage imter of soils receiving different sails. 



In the experiments with sandy soils in tubes referred to above none of the chlorid 

 or sulphate of pf)tassium was lost in the soil containing the least amount of calcium 

 carbonate, while in the soil containing 91.07 per cent of this substance there was a 

 loss of 05 per cent of the cidorid aii<l 2S per cent of the sulphate. "Tiie al)sorption 

 of potash by these peculiar soils is influenced chiefly l)y their content of lime carbon- 

 ate for several reasons. The liigher the percentage of lime carbonate the lower must 

 be that of tlie double silicates in the respective soils. . . . and these silicates are 

 particularly instrumental in holding potash. . . . On account of the basic nature of 

 Hawaiian soils, and their smaller content of double silicates as compared with 

 American soils, as a rule, potassic fertilizers are much more readily disseminated 

 throughout the soil mass by means of rain or irrigation water." 



