'jd FERTILITY AND FERTILIZER HINTS 



manufactured in Germany in 1893 was 750,000 tons; in England 

 160,000; in France 115,000, making the total production of 

 central Europe about 1,000,000, a quantity sufficient to fertilize 

 nearly 5,000,000 acres. During the year 1907, it is estimated 

 that German agriculture made use of from 1,500,000 to 1,600,000 

 tons of basic phosphate slags. The total output of basic slag 

 is undoubtedly not far from 2,000,000 tons. The total produc- 

 tion of basic slag is therefore approximately one-half of that of 

 crude phosphates.^ 



This product is sold in the form of an inpalpable powder which 

 is black in color. The phosphoric acid in basic slag is often rated 

 as valuable as the phosphoric acid in bone-meal. The composi- 

 tion of this product is variable depending on the amount of phos- 

 phoric acid in the iron ore, but it is possible to obtain this pro- 

 duct containing 23 per cent, of phosphoric acid, but the lower 

 grades are most common. It averages about 14.20 per cent, of 

 phosphoric acid. On account of the large amounts of iron oxide 

 present, it is not suitable for manufacturing artificial fertilizers.* 



Phosphatic Guanos. — These guanos are of the same origin as 

 nitrogenous guanos. They are the excreta of sea fowls. Be- 

 fore the phosphate deposits were discovered in the United States 

 these guanos were imported into this country and used largely by 

 the manufacturers. All of these guanos originally contained 

 nitrogen. However the nitrogen, soluble phosphates, and 

 alkalies have disappeared by decomposition of organic matter 

 and leaching of water, so that most of them only contain traces of 

 nitrogen. The phosphoric acid is in the form of tricalcium phos- 

 phate and insoluble in water. Some of these guanos contain too 

 much iron and alumina oxides to manufacture profitably. They 

 are not imported into the United States very much now, as many 

 of the deposits are exhausted or else too expensive to compete 

 with our native mineral phosphates.* 



It should be understood that there are many other phosphates 

 used in other countries but they cannot compete with our mineral 

 phosphates and therefore are not found on the American market. 



> Wiley, Principles and Practice of Agricultural Analysis, Vol. II. 



