The alkalization of two brown-water bog lakes has been reported 

 recently by Hasler et al, (195l) » Objectives of this investigation were to 

 neutralize the acidity (pH 5oii to 5o6) and increase light penetration by 

 the precipitation of humic colloids as lime humate. The addition of limate 

 and calcium carbonate to the water brought pH to neutrality, increased the 

 carbon=dioxide reserve, light penetrationj total phosphorus, and organic 

 nitrogen,, while the ammonia and nitrite nitrogen^, iron, and sulfate content 

 were decreased. These effects were more pronounced in the lake that received 

 heavy lime applications early in spring than in the one that received pro= 

 longed applications throughout the summero Cost was about 60 cents per acre- 

 foot. 



Shortcomings are evident in these lake=f ertilization reports. In gen- 

 eral appraisal of work done, it might be said that treatment preceded diag- 

 nosis, Pretreatraent data, necessary for the interpretation of fertilizer 

 effects, were weak and insufficiento Post-treatment observations were more 

 numerous and carefully done, but were not of the quality and quantity 

 demanded by the situation. Proper consideration was not given to the many 

 variables that affect the intricate mechanism of nutrient enrichment. Thus, 

 conclusions reached were often either assumptive, or too broad to contribute 

 information of significance. 



Conclusions oft Lake Fertilization 



Similarities occur in the effects of fertilizers in lakes and in ponds, 

 as might be expected. Population increases were rapid and most pronounced 

 among the lower organisms. Single species, rather than whole groups, tended 

 to show greatest gains,. Nutrients disappeared rapidly from solution, ap- 

 parently through deposition in bottom soils and uptake by living organisms. 

 Lake-fertilization results differed from those of ponds in that less notice- 

 able changes occurred after the addition of nutrients, especially to fish 

 life. The effects of fertilization on fish were not included in the reports 

 of Smith (1931) s Langford (19^0), and Hasler et al. (19^1) . Fish did not 

 benefit from the first h years of lake enrichment described by Juday et al 

 (1938), or in the experiments performed by Ball (1950) and Wales (19^0) . 

 Nutrient applications were of questionable value to fish in two cases 

 (Juday et al., 1938| King, 19U3) ., while Taylor (19hh) and Smith (19h8b, 

 1952) indicated definite growth increases. All in all, fish may have pro- 

 fited from fertilization in one warm-water and two cold-water lakes. The 

 biological destruction of two lakes by the artificial enrichment described 

 by Ball (1950), and Ball and Tanner (19^1) demonstrates a possible pitfall 

 in tampering with the natural metabolism of lakes. Perhaps there have been 

 other negative attempts at lake fertilization which, although noteworthy at 

 this time, have not been r eported. In concluding the various results, it 

 can be said that fertilization increases at least part of the productive 

 capacity of lakes, but not necessarily the yield of fish. It is possible 

 that fertilization may become a valuable technique in raising the productive 

 levels of some lakes, and an important method of studying the biological 

 interactions and little-known chemical relations of lakes in general, 



25 



