122 SOILS AND FERTILIZERS 



the blood and debris from slaughter-houses. Fre- 

 quently small amounts of salt and slaked lime are 

 mixed with the blood. It is richest in nitrogen of 

 any of the organic manures. When thoroughly dry 

 it may contain 14 per cent, of nitrogen. As usually 

 sold, it contains from 10 to 20 per cent, of water, and 

 has a nitrogen content of from 9 to 13. Dried blood 

 contains only small amounts of other fertilizer ele- 

 ments ; it is strictly a nitrogenous fertilizer, readily 

 yielding to the action of micro-organisms and to nitri- 

 fication. On account of its fermentable nature, it is 

 a quick-acting fertilizer, and is one of the most valu- 

 able of the organic materials used as manure. It 

 gives the best returns when used on an impoverished 

 soil to aid crops in the early stages of growth, before 

 the inert nitrogen of the soil becomes available. 

 Dried blood may be applied as a top dressing on grass 

 land, and it is also an excellent form of fertilizer to 

 use on many garden crops, but it should not be placed 

 in direct contact with seeds, as it will cause rotting, 

 nor should it be used in too large amounts. Three 

 hundred pounds per acre is as much as should be ap- 

 plied at one time. When too much is used losses of 

 nitrogen may occur by leaching and by denitrification. 

 It is best applied directly to the soil, as a top dressing 

 in the case of grass, or near the seeds of garden crops, 

 and not mixed with unslaked lime or wood ashes, but 

 each should be used separately. As all plants take up 

 their nitrogen early in their growth, nitrogenous fer- 

 tilizers as blood should be applied before seeding or 

 soon after. An application of dried blood to partially 



