122 MINNESOTA STATE HORTICULTURAL SOCIETY. 



are very rich in phosphoric acid and nitrogen. If burned the nitrogen, 

 the* best part, is wasted. They should be ground or pulverized in some 

 way before being used in a clean state. They are much more readily sol- 

 uble if the grease is extracted, for the grease prevents chemical action. 

 They may also be softened by being somewhat broken, piled up in layers 

 of wood ashes, bones and hot stable manure and covered over with earth 

 after being well watered. The use of the earth is to retain the ammonia 

 that may be volatilized by the violent chemical action resulting from the 

 action of the ashes on the manure and on the bones. It is a good plan to 

 mix ground bone in the manure piles as its plant food is made more avail- 

 able. 



Bones are often called lasting manures because the effect of their appli- 

 cation is seen for a long time; this is because they are not at once decom- 

 posed into soluble plant food, but plant food is forming from them for a 

 longtime. They do not come under the head of quick acting manures, 

 but are often rendered so by treating with sulphuric acid, by which the 

 phosphoric acid is made soluble. This is a disagreeable and expensive 

 operation, and should not be attempted at home or on a small scale, 

 where it is more practicable and almost as well to mix them after grind- 

 ing in heating manure. 



Marl. This material varies in composition, but generally is entirely or 

 largely composed of carbonate of lime, which is useless as a plant food in 

 our soils. 



Some of them contain a little phosphoric acid and nitrogen, which is of 

 some value. All marls must be bought at an exceedingly low price to 

 have it pay to use them at all while many are valueless. There is a very 

 common opinion at present that they are all good fertilizers. 



Nitrate of soda. This is composed of nitric acid and soda. It comes 

 from Chili, where it is found on the surface of dry soils. It is known in the 

 market as Chili saltpeter. This is a very quick acting fertilizer. It con- 

 tains nitrogen in the form of nitric acid, which is the form in which it is 

 taken up by the plant. On this account it has proved to be an almost 

 special fertilizer for early spring garden crops, because it furnishes plant 

 food at once available to the plant, while in stable manure and other fer- 

 tilizers the nitrogen must be changed into the form of nitric acid first. 

 Stable manure then contains but little real soluble plant food, and conse- 

 quently it is best adapted to late crops, for which it has a supply of free 

 plant food formed during the growing season by chemical action. 



HOME MADE MANURE. 



By home made manure I mean all the excrements of all animals on the 

 place and all material that will decay and make manure when added to a 

 compost heap. 



These should be looked upon by gardeners and farmers as the most im- 

 portant source of manure, and if any are bought it should be with a view 

 of using them to supplement these. 



In the stables, pig pens, sheep yards and hen houses sufficient absorbing 

 material should be used to take up all the liquid portion of the excre- 

 ments, as this contains much more plant food than the solid portion. 



The manure pile should generally be under cover for it may lose much 

 of its value by leaching in rains, but it may also be too dry. Also remem- 



