BLACK BASS CULTURE 183 



ton production. The effect is here indicated by the averajre numboi- 

 of Crustacea, exckisive of nauplii, based on from G8 to 70 samples 

 taken from each of these ponds. C 1 was fertilized with super- 

 phosphate, and the average number of Crustacea per liter was 484.41 ; 

 C 2 was fertilized with soybean meal, and the average number of 

 Crustacea per liter was 1,812.21 ; C 3 fertilized with shrimp bran pro- 

 duced on the average 621.4 Crustacea per liter; for C 4, the control 

 pond, the average number of Crustacea per liter was 265.72; in C 6, 

 fertilized with sheep manure the average number of Crustacea was 

 660.4. These results show^ that each one of these fertilizers exerted 

 a beneficial effect, but that the effect was most pronounced in case of 

 the soybean meal. 



When using fertilizers the question arises as to whether it is pref- 

 erable to apply all of the fertilizer at one time or to make smaller 

 applications at relatively short intervals. The latter procedure is 

 probably the more economical. Most ponds have a considerable 

 amount of seepage and if the whole amount of fertilizer is put in at 

 one time there is necessarily some loss of nutrient material. Further- 

 more, a large dose of fertilizer may produce such a high concentra- 

 tion of some plant nutrient as to be harmful rather than beneficial. 

 Still another objection is the possibility that the presence of large 

 quantities of nitrogenous materials may encourage the activities of 

 denitrifying bacteria and thus cause a loss of valuable nutrients. 

 Finally, if a heavy application of organic fertilizer is made in warm 

 weather, it may so deplete the supply of dissolved oxygen as to 

 endanger the fish life in the pond. For these reasons we have adopted 

 the method of applying fertilizers in small quantities at short inter- 

 vals rather than resort to infrequent applications of large amounts. 



In applying fertilizers the different constituents are weighed and 

 then mixed in the proper proportions. Small amounts of the mixture 

 are distributed over the shallow areas along the margin of the ponds 

 during the spring and early summer at intervals of about 10 clays to 



2 weeks. The mixture may be applied dry, but if the wind is strong, 

 it is better to moisten the fertilizer before attempting to scatter it 

 over the water. 



The amount of fertilizer to be used will depend to a large extent 

 on local conditions. If the pond soil is infertile, more fertilizer will 

 be required than in ponds built in fertile soil. In our work with the 



3 to 1 mixture of sheep manure and superphosphate, we have found 

 that 550 pounds per acre for the entire season gave very satisfactory 

 results. During one season we used from 670 to 742 pounds per 

 acre. The results, however, were no better than when 550 pounds 

 per acre were used. In the small ponds as much as 936 pounds 

 per acre were used. In one of these ponds 56 per cent of 

 the bass put in as fry in June were removed as fingerlings in October. 

 This is the highest percentage of survival that we have had at the 

 Fairport station. Very good results have been obtained in the small- 

 mouth black bass pond, when 472 pounds of a 3 to 2 mixture of sheep 

 manure and superphosphate were used. It is possible, however, that 

 the results would have been even better if more fertilizer had been 

 used. 



117574°— 30 2 



