TECHNIQUES OF FISHPOND MANAGEMENT 74 
that of soybean meal is similar or slightly lower (table 3). The 
fertilizer materials in these meals are not soluble and the meals must 
decay before they are available. Seed meal is fish food as well as 
fertilizer; the fish sometimes eat the meal before it decomposes. 
Hay may be tried as a fertilizer in regions where farm manure 
is scarce or where it is necessary to fertilize ponds with inexpensive 
farm products. The fertilizer formulas for various hays are: 
Alfalfa hay 2.3-0.5-0.9; bluegrass hay 1.5-0.5-1.5; and timothy hay 
0.8—0.2-0.6. All hays must decay before they fertilize the water. 
Experiments have been conducted at Fairport, lowa, to determine 
the effect of various organic fertilizers on the production of plankton 
and bass fingerlings (3). A 3-to-1 mixture, by weight, of sheep ma- 
nure and bonemeal gave only fair results, possibly because the phos- 
phorus in bonemeal is insoluble. Various mixtures of sheep manure 
and superphosphate were tried and it was concluded that a 1-to-1 
mixture gave the best results and is preferable to a 3-to-1 mixture. 
The effect of various fertilizers on plankton production was tested 
with the results shown in table 4. Each of the fertilizers increased 
plankton production, the greatest increase, 681 percent, being ob- 
tained with soybean meal. The fertilizers were applied from June 
to October and the amount varied from 472 to 742 pounds per acre 
for the season. With a 3-to-1 mixture of sheep manure and super- 
phosphate, best results were obtained when 550 pounds were applied; 
472 pounds of a 38-to-2 mixture gave good results. The maximum 
production of bass fingerlings was obtained when soybean meal was 
used at the rate of 700 pounds per acre. The conclusion reached was 
that, for the production of fingerling bass, these fertilizers should 
be used at the rate of 500 to 1,000 pounds per acre per season and be 
distributed in small amounts at short intervals. 
Sewage sludge, tankage, and other such organic byproducts have 
been used experimentally in Europe but practically not at all in this 
country. However, these should receive consideration since in some 
localities they may be obtained cheaply. 
TABLE 4.—Plankton production at Fairport, Iowa, as affected by various 
fertilizers (3) 
ae Crustacea ros Crustacea 
Fertilizer perliter Increase Fertilizer per liter Increase 
Number | Percent | Number | Percent 
Superphosphate__------------! 484. 41 UPA PIN eee eS 260 2n| eee 
Soy beansneale a ee Se tae Si 2K 681" |;Sheepamnanure: 225.282 Se | 660. 40 248 
Shiai branes seen soe ae | 621. 40 232 
In Europe manures have been used in carp and tench (7 7inca sp.) 
production, but in this country, the use of farm manures for pond fer- 
tilization is experimental. Sheep and cow manures have been used to 
increase hatchery -production of fingerling warm-water fishes. As 
much as 3 tons of cow manure is used in one season to fertilize 1 acre 
of hatchery pond. 
When farm manures are used for pond fertilization, the possibility 
of the transmission of parasites and diseases—both livestock and hu- 
man—must be constantly borne in mind. The two most likely to cause 
