2028 The Cornell Reading Courses 



It is not possible to fertilize successfully a pond of the type herein 

 described if there is any appreciable current through it, for the essential 

 elements of fertilization will be 



Q^ 



(DJ3 



rapidly carried away. However, if 

 one desires to try it, a very effective 

 method consists in first buildinj^ 

 several small ponds, about fifteen 

 or twenty feet in diameter, along the 

 margin of the main pond, connecting 

 them therewith by narrow chan- 

 nels (Fig. 187). By placing well- 

 rotted manure in these ponds at. Fig. 187.— A suggestion for increasing the 



the rate of about three quarts per supply of food for fish in a pond A, 



forage ponds; B, screens; C, matn pond 

 square yard of pond area and one 



week later by introducing mud and vegetation from some pond known 



to contain the necessary organisms, it is very probable that during the 



course of the next three weeks, there will be enough Protozoa, minute 



Crustacea, and the like, to feed all of the young fishes that may appear. 



These small forage ponds must be screened with galvanized woven-wire, 



having a mesh no greater than one-quarter of an inch. Advanced fry 



will soon find the forage areas and will pass through the screens, which, 



however, will effectively keep out the larger fishes. 



There is every reason to believe that pond fertilization follows the same 

 principles that are involved in the fertilization of land. In the latter case, 

 it is a recognized fact that every field is a problem in itself; this is true 

 in respect to ponds. Hence the amount of fertilizer given in the pre- 

 ceding paragraph for a square yard of pond area is purely tentative. It is 

 merely a starting point from which to vary the amount as experience 

 is gained. 



Even in the main pond itself there will be some natural fertilization 

 each year derived from decaying vegetation, from excrement from fishes, 

 and by solution from bottom soil. This will provide small food organisms 

 for a limited number of advanced fry. The production may be increased 

 by the addition of leaves and waste hay or even by a small amount of 

 horse manure. This should be spread along the margin of the pond 

 early in the spring, and, at the same time, the amount of water flowing 

 through the pond should be cut down to the minimum. Only a narrow 

 strip along the margin should be thus fertilized, for if too great an area 

 is so treated, pollution of the whole pond will follow, which will be fatal 

 to the pond organisms. 



Food Jor adult fishes 



Insects. — Since there is no known method for controlling the repro- 

 duction of aquatic insects in large numbers, one will have to depend on 



