Reclamation of Old Ponds and Lakes 



In southern ponds and small lakes where the submersed aquatic 

 plants have already become abundant, Smith and Swingle (1942) 

 have recommended a fertilization program beginning in December or 

 January. One of the fertilizers listed above may be added at 

 about monthly intervals until warm weather sets in. In this 

 interval, filamentous algae, such as Spirogyra and the semi- 

 microscopic forms attached to the leaves and stems of old plants 

 may develop in abundance, growing over areas formerly occupied by 

 the coarse submersed aquatic plants, or upon old or living plants. 

 At the onset of warm weather, these filamentous algae, stimulated 

 by winter fertilization, begin to decay. Meanwhile, the growth 

 of the submersed plants or their seedlings or new sprouts has been 

 inhibited. With warm weather, the intervals between applications 

 may be increased to weekly periods until the water becomes green 

 with "water-bloom". As in farm pond fertilization, the microscopic 

 plants shade out the larger submersed plants. Rooted plants may 

 break loose and float, forming a scum on the water surface. Oxygen 

 depletion sometimes occurs from too much fertilizer being added at 

 this time. The addition of more nitrogen in fertilizing materials 

 may speed up the decaying process. 



This method of plant control by fertilization was tried out 

 at a more northern latitude--Deer Lake near Boonton, New Jersey, 

 (Surber, 1948) --with a program of fertilization beginning as soon 

 as the ice cover left the small (44-acre) recreational lake. The 

 fertilization plan, followed in Deer Lake and other artificial 

 lakes in this area, is described below. The project in Deer Lake 

 proved successful in spite of relatively-large inflows of water. 

 Seven applications of 5-10-5 fertilizer were made. Applications 

 at the rate of 50 pounds per acre were begun on March 16 (one 

 week after the ice went out) . Subsequent applications were made 

 on April 13, May 11, June 8, June 15, June 21, and June 28. The 

 application on June 8, when the weather became warm, was at the 

 rate of 100 pounds per acre, instead of the usual 50 pounds. A 

 bloom appeared after the first application, but good blooms were 

 not present until after June 8. 



The control of weeds in Deer Lake offered special problems, 

 because it was used for recreational purposes by 400 families. 

 Almost immediately after fertilization, water-bloom algae appeared. 

 This feature differed from the results in the south, where filamentous 

 algae appeared early and began decaying when warm weather set in. 



In Deer Lake, coontail, which occupied the open waters and 

 interfered with sail-boating, was destroyed first. This plant 

 disintegrated, creating a high oxygen demand and probably con- 

 ditions unfavorable for other plants. Anacharis , bearing abnormally 



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