SCIENTIFIC AGRICULTURE. 197 



[If we allow the quantity of urine voided by each indvidual to be 

 COO pounds yearly, the city of Rochester, which contains 30,000 inhabi- 

 tants, would furnish yearly 1,200,000 pounds, or 540 tons. This, esti- 

 mated at the price of guano would be worth $21,600. Now if we esti- 

 mate the number of horses and cows of the city to 500 of each, and 

 that each animal voids as much urine as two persons, the amount would 

 be 80,000 pounds, or 40 tons, which would be worth $1,600. Here 

 then is a loss, if we reckon guano at $40 per ton of $23,200: or of 

 manure enough to produce, in addition to the ordinary crop, over 

 16,000 bushels of wheat in a single year. These calculations may not 

 be correct, but they approximate this point sufficiently for our purpose.] 



VEGETABLE MANURES. 



Organic vegetable matters in various conditions, constitute 

 the largest part of manure in use. The form in which they 

 are prepared and applied has an important influence on their 

 fertilizing effect. The principal difference between dry and 

 green vegetable matter is, that the latter decomposes more 

 rapidly and therefore acts more promptly. Unripe plants fur- 

 nish a more valuable manure than ripe ones. 



Straw and chaff, when ploughed into the soil dry, are slow 

 in decomposing, and act more slowly than when previously 

 fermented. The question of applying straw without previous 

 decomposition, is, in practice, only a question of time. It is 

 doubtless true that it furnishes about the same amount of 

 manure in both cases ; but in the one case it has a more 

 speedy and powerful, and in the other a more prolonged effect 



Saw dust, is a cheap, and on some accounts a valuable ma- 

 nure : it ferments slowly in the soil, and cannot, therefore, be 

 much relied upon the first year or two. It is beneficial in ab- 

 sorbing gases and liquid manures, and its effect is felt gradually 

 by the soil as decomposition proceeds : . it is also beneficial to 

 stiff clay land by rendering it more loose and light 



Dry leaves and decayed wood, operate as manures in a man- 

 ner similar to saw dust ; they are however better fitted by 

 decomposition in compost heaps. 

 *17 



