Experiments on the Effects of Various Kinds and Combinations of Chemical Fertilizers on the Reproduction of Daphnia longispina-II

Abstract

The results obtained from the fertilization, experiment on the reproduction of Daphnia longispina are as follows:
1) The fertilizers used in the experiment are ammonium sulphate, urea and calcium super-phosphate in the ratio N:P₂O₅=l:1 (shown in Table 1).
Good reproduction of Daphnia is obtained from the ratio N:P₂O₅=2.5:2.5ppm-5:5ppm, further the opitimum value of fertilizers is N:P₂O₅=5:5ppm, the bottom mud used in this experiment was loam (shown in Table 2, 3).
2) The value of fertilization was differed by the quality of bottom mud. Good rep oduction was obtained from the fertilization of N:P₂O₅=2.5:2.5ppm-20:20ppm, (the range of this value is comparatively wide) changing the bottom mud from loam to sand and N:P₂O₅=20:20ppm-30:30ppm in the case of no mud (shown in Table 2, 4).