35 



That is to say, an application of 2,000 pounds of barnyard 

 manure brings into the soil practically only 12 pounds of nitro- 

 gen, 13.40 of potash and 6.3 phosphoric acid, — very small 

 amounts. An average cropping is found to remove from one acre 

 of land, in one year — 50.5 pounds nitrogen ; 41.6 pounds potash ; 

 19.1 pounds phosphoric acid. 



To return these amounts to the land would require, — 8,333 

 pounds of barnyard manure for the nitrogen ; 6,332 pounds of 

 barnyard manure for the potash ; 6,064 pounds of barnyard manure 

 for the phosphoric acid. 



These figures show that barnyard manure contains too little 

 nitrogen in proportion to its potash and phosphoric acid, and this 

 has been proven over and over again. Of all plant food, the soil 

 lacks and needs most nitrogen. 



As to the proportion of potash and phosphoric acid : they are 

 shown by the last two weights given to be replaced in the soil by 

 nearly the same weight of barnyard manure. This might suit in 

 some soils, but in very many it would not. In England they find 

 this proportional amount of phosphoric acid too little, while in 

 Massachusetts the proportion of potash is too little. 



Barnyard manure excels, therefore : — 



1. Because it brings into the land a large amount of the much- 

 needed humus. 



2. Because it contains some of every kind of plant food. 

 Nothing can take the place of barnyard manure. 



It is deficient. 



1. In all the three costly elements of plant food. 



2. Especially in nitrogen. 



3. For Massachusetts, in potash. 



It must therefore be re-enforced by all three elements, especially 

 by nitrogen and potash. 



III. — How to make Barnyard Manure. 



Barnyard manure should be made with reference to the preceding 

 and the following statements. It should be made under cover, to 

 prevent the addition of an excess of rain water. It should be 

 made in a room with water-tight floor and sides, in order to pre- 

 vent drainage, the drainings being the most valuable part. It 

 should not be stored under or over stock, because of its unhealthy 

 gases. 



Apparently the most economical arrangement which meets these 

 conditions is a room placed in the rear of a horse or cow stable, 

 running parallel to the latter and separated from it by a tight wall 

 provided with slide windows, through which the manure may be 



