Liming is preferably done about 2 weeks before the addition of ferti- 

 lizers^ to avoid binding nutrients in insoluble calcium compounds. The 

 degree of caustic action desired^ and the activity of the soil vary the 

 dosage from 90 to 3^0 pounds per acre. Liming^ in a more general sense, 

 covers the addition of noncaustic lime compounds (limeston8_, lime marl) 

 which may accomplish all purposes except the first. Such lime may be 

 included with the fertilirers. Sandy bottoms and calcium- rich waters may 

 derive little benefit from liming. 



Proper stocking, as to species composition and numbers^ is essential 

 for maximum productivity. Stocking, tables can be found in the literatures 



Schaeperclaus (1933) = . <■ comprehensive 

 Wiesner (1937) , , , o , « salmonids 

 Swj-ngle and Smith (19^0) , pondfish 



The fishes involved in fertilization work are listed in the appendix 

 with references to the papers in which they appear. The total yield of 

 fish per unit area varies, as does stocking density, with species and 

 population composition. Generally, oroductive increase in enriched oonds 

 is' reckoned at 100 percent over unfertilised ponds. This may be expected to 

 vary considerably in different geographical locations and with different 

 types of fis^i. It is readily understandable why omnivorous carp can be 

 produced in greater quantity than can carnivorous fish such as bass. Maxi= 

 mum yields of carp and related species in Asiatic countries., as cited by 

 Hora (19^0), generally range fron 2,000 toU^OOO pounds per acre per year. 

 On the other hand, Sid.ngle and Smith (195o) claimed that fertilized Alabama 

 ponds produce UOO to 600 pounds of sport fish per acre compared with I4O to 

 200 pounds per acre in unfertilized ;)onds. Properly fertilized waters in 

 our northern latitudes may show only 30-percent increase over control ponds 

 because of the shorter growing season. 



Conclusions on Pond Fertilization 



Experiments in pond enrichment have ^^enerally revolved about the 

 testing of common fertilizer t,-;T3es and concentrations relative to the pro- 

 duction of food organisms and various species of fish. In these trials, 

 near-isomorphic ponds have been used as typical test and control units. 

 Some experimental work, of course, has not followed this pattern, Hender- 

 son (19li9) tested the value of manganous sulfate as a plant stimulator, 

 and was apparently successful in oroducing the desired algal blooms with 

 concentrations of 0.1 and 1,0 part per million. Walker (I9I49) failed to 

 Increase production by adding limestone to acid ponds. Weed control by 

 fertilization has been an interesting sidelight. Surber (I9U?) found that 

 hay plus superphosphate effectively controlled overabundant flora. Organic 

 and organic-plus-superphosphate fertilizers produce heavy algal growths 

 which can be destroyed by sodium-nitrate applications 5 according to Smith 

 and Swingle (19U3) , Patriarche and Ball (19149) were unable to control 

 algae as suggested by these authors. Productive increases of fish have 



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