Table 4. --Inorganic fertilizer formulas (N-P-K) , 

 composition in pounds per acre 



Pounds of 

 Fertilizer ingredients 10-6-4 8-8-2 6-8-4 5-10-5 



Ammonium nitrate (33.57o N) —' 



Superphosphate (20% P2O5) 



Muriate of potash (60/!, K2O) 



Filler £.' (powdered limestone, sieved 



marl, sand, peat, etc.) 33 32.5 35 27 



100 100 100 100 



l_l In hard or alkaline waters, ammonium sulfate (20% N) should be 

 used. Pounds per acre for the four above formulas are 50, 40, 

 30, 25 pounds, respectively. 



2^1 Filler not needed when above N-P-K fertilizer components are 

 added directly to the pond. 



The former practice in applying fertilizers was to broadcast 

 them from the shore, or a boat, into the water. This may still be 

 done, but limnological observations in farm ponds in the south 

 showed that pond waters become stratified during the warmer months 

 and that often there is a non-circulating layer of low-oxygen 

 water near the bottom. Lawrence (1954) recommended the construc- 

 tion of horizontal platforms of about 3.5 feet square area placed 

 one foot below the water surface with a walkway leading out to it. 

 These platforms were located 12-15 feet from shore at the end of 

 catwalks at points where wave action of the surface waters could 

 dissolve away the fertilizer. The sacks of fertilizer are placed 

 on them with the uppermost sides ripped off. Fertilizers were thus 

 dissolved into the surface layer of water where most needed for the 

 stimulation of phytoplankton growths. One such platform located 

 at a point where wave action or movement of waters is greatest 

 suffices in ponds of 1 to 5 acres. One platform for 8 to 10 acres 

 in larger ponds is recommended. 



Owners of small ponds may find it more convenient to buy more 

 concentrated fertilizer such as 20-20-5 in smaller (40 pound) sacks, 

 the total contents of which produce results equivalent to the active 

 ingredients within the 100 pound bags. 



Where ponds do not respond to fertilization by the above 

 methods, liming may be required. Where the water has a total hardness 

 of less than 15 p. p.m., Zeller and Montgomery (1958) recommended 

 about 1000 - 1500 pounds per acre of agricultural lime or basic slag. 



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