the regular wintering of the ponds also, especially of nurserj'' and brood growing ponds, 

 it is to be reconnended to cultivate the pond bottom and plant it with mixtures of oats, 

 also rye and barley, etc. The plants, especially the deep rooted ones, contribute to 

 better drying out of the soil and promote the course of bacterial decomposition processes 

 in the soil. A crop or a soil fertilization can be achieved at the same time. The 

 yields by soil fertilization alone — imniaterial whether the plants are left standing or 

 turned under — are considerably increased. Thereby there are conditions similar to those 

 of new water coverage. The experiments in Sachsenhausen according to Czensny and Y.'undsch, 

 have shoViTi, however, that the total special grov/th was about 43.2 percent better in the 

 first time covered ponds than in the twice covered ponds if no fertilizing was done and 

 about 88.1 percent better with full fertilization. It must, however, be pointed out that 

 Schieraenz and Zuntz have taken up the opinion, viiich was later again adopted by Nordquist, 

 that it is not advisable to regularly drain the ponds over the ivinter, because great 

 numbers of nutrition-animals are caused to perish. 



Regarding the prospective success and usefulness of a soil cultimation, it is shovn 

 from what has been said, that soil cultivation must be profitable in the first place 

 with ver:,' strongly reeded soils, and in the second place with "thickly humus-layered" 

 soils, and therefore with fertile ponds. Y.'ith poorer and average ponds, soil culti- 

 vation even if it is merely tearing up the soil, can be even injurious, which Demoll 

 very correctly emphasizes. If the soil cultivation combines tillage and a relatively 

 prolonged drainage, it is naturally profitable on poorer soils. In the operation of 

 carp pond industries in full activity, it should be seen too, that the soil cultivation, 

 aside from reed control purposes, should be regularly applied above all to ponds which 

 are to be used for growing of brood to one-summer fingerlings. Only after this do other 

 ponds come in line for consideration, and first of course, those with the most fertile 

 soils. 



The soil cultivation may be started as soon as the pond bottom is sufficiently 

 dried out and firm. This is unfortunately often not the case until spring. I shall 

 name the plow as the first implement for soil cultivation. Multiple plows, moor plows, 

 special motor attachment plows, and others are in use. For pulling wheel tractors, 

 caterpillar tractors (chain tractors), also oxen and horses, may be used (see Fig. AB 

 and /t9). Moor tilting-plows, which are drawn back and forth by tractors vfith rope 

 vdjiches, are very usable, according to Gennerlch (1932). 



Fig. A8. Standard plowing up of a carp-brood nurserj'- pond with a 

 single shared motor tractor plow. A wheel tractor serves for pulling. 

 The clods are turned about 180° and pressed down by an attached 

 annular roller. 



159 



