438 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



Professor Mapes said that the Jersey gardners made it a rule 

 to appropriate all the manure that could be obtained. He con- 

 tended that the value of stable manure consisted in the amount 

 of inorganic matter which it contained. The organic matter was 

 useful to any soil not properly plowed. But to thoroughly disin- 

 tegrated and subsoiled land, the atmosphere would supply all the 

 ammonia that it could require. When the farmer has to contend 

 with a bad soil, he naturally becomes more dependent on manures 

 for his excitants. He would refer, in elucidation, to experiments 

 made by himself. He once added, to a thoroughly cultivated 

 field on his own farm, sulphate of ammonia in crystals and in 

 other forms, but it did not affect the crops one iota. But in his 

 neighbor's field, where the land was not subsoiled, the organic 

 matter was of very great use. Then the effects of rain are care- 

 fully to be noted. The first half pint of a shower, on a warm 

 day in summer, is full of gases, and in percolating through the 

 soil these are retained. 



In soils that are heavy and clayey, it was frequently necessary 

 to plow in straw or long manures, to admit a free circulation of 

 the air, an operation supplying mechanical advantages that can- 

 not be over-lauded. Certain farmers are pleased, in manuring, 

 to have their fields reduced to a kind of saponaceous consistency, 

 while others are satisfied with merely throwing their manure on 

 the surface of the soil, and report that they have found as much 

 benefit from this practice as if the manure had been buried in 

 the soil. But we are very liable to mistake one action for 

 another. If a plank be placed upon the grass, it will be found 

 that after the obstacle is removed the grass will grow taller, 

 fresher, and be in every respect more flourishing than that in 

 any other part of the ground. If carpenters' shavings be 

 placed over the grass, the effect is the same. This is in effect 

 what is called mulching, a practice that farmers frequently resort 

 to even for grass field. The principal use of top-dressing is its 

 action as a mulch, preventing the water which falls on the soil 

 from freezing, and allowing it to percolate freely to the roots of 

 the plants. Where the land is mulched, there is generally an 

 earlier spring and a later winter. Therefore the mistake is in 

 considering the action of the mulch as that of the manure, and 

 attributing to the manure on the surface the effects which it pro- 

 duces mainly as a mulch. 



It is an established fact that manures should contain some 



