59 
could be used. As no vegetation test was made with guano No. 1017, 
the citrate-soluble portion, 18.52 per cent, is taken as the available 
phosphoric acid. Of this guano 546 pounds is required. The mix- 
ture thus contains 320 pounds of guano No. 881, 215 pounds of a high- 
grade potash salt, and 546 pounds of guano No. 1017, a total of 1,081 
pounds. The 1,081 pounds of mixture is equivalent to 1,000 pounds 
of the 3:12:12 formula. 
It will be noted that, in using the guanos to make a formula, the 
availability of the nitrogen and phosphoric acid in the guanos was 
considered, as well as the total amount of these elements present. 
It should be borne in mind that in the analyses given in the first part 
of this report percentages are all calculated on the dry material. The 
material as it exists in the cave contains 10 to 60 per cent of moisture, 
and the air-dried material contains 3 to 15 per cent moisture. For 
moist material, the percentages must therefore be reduced and the 
quantities of guano utilized increased. 
MATERIALS FOR MIXING WITH GUANOS. 
Most guanos can be mixed with any of the commercial fertilizers 
without loss of availability in the mixture. A few guanos con- 
taining carbonate of lime, should not be mixed with sulphate of 
ammonia or acid phosphate. A test for carbonate should be made 
by observing whether the guano effervesces with acid before mixing 
a guano with such materials. If it is desirable to use a guano con- 
taining carbonate with sulphate of ammonia, the sulphate of ammo- 
nia should be applied to the soil first and later the guano incorporated 
with the soil. On the other hand, a few guanos contain considerable 
ammonium salts, and these should not be mixed with basic slag, as 
the free lime of the slag will liberate the ammonia. 
As certain guano deposits have a peculiar place utility in being 
located in districts where transportation charges make commercial 
fertilizers particularly expensive, it is important to use them with 
other waste fertilizing materials, if possible. A combination of 
tobacco stems and bat guanos would be equivalent to a complete 
mixed fertilizer, the tobacco steins furnishing potash and some nitro- 
gen, the guano phosphoric acid and some nitrogen. Where more 
potash in proportion to the other elements is desired than can be 
obtained by mixing guano and tobacco stems, wood or bagasse ashes 
can also be applied, although the ashes should not be mixed with 
some guanos. 
Guanos can also be used to supplement stable manure, as stable 
manure is relatively deficient in phosphoric acid. A phosphatic 
guano can be advantageously added to the compost heap as it is 
