{O The bottom of the pond is greatly improved through liming. It will lead 

 to speedier decomposition of mineralSj to base exchanges and liberation 

 of potash; it will bring about a neutral reaction of the soil and vdll 

 speed up the decomposition of the soil. Hand in hand with all this goes 

 a greater resistance of the soil against disease promoting bacterial 

 colonies and parasites through lowering the amount of organic substances, 

 necessary for the existence of these pests. Furthermore, the often 

 dangerous amount of oxygen consun^stion will be greatly lowered through 

 mud elimination. 



(5) Sy liming the water, strong excesses of putrescible organic substances 

 are precipitated and eliminated, as proved by Ebeling's experiments. By 

 this means in times of danger the conditions for the existence of many 

 disease instigators (gill rot instigators) are eliminated. The oxygen 

 content, 1*1 ich is extremely important for the existence of the fishes and 

 also for the fertility, is indirectly increased. The expectations of the 

 practitioner in this respect are of course frequently exaggerated. 

 Ebeling has shown that under conditions usually existing with gill rot, 

 even a liming of 1,425 pounds of quick lime per acre in nine days exerts 

 no appreciable influence on the oxygen content. 



It follows from all this that liming is necessBiTv in case of too low pH rate and 

 a low A.C.V. It is also indicated and strongly recommended in cases of very muddy and 

 neglected bottoms, in case of gill diseases during the summer months, when the rate of 

 organic matter is always rather high, i.e. whfen the K 1^ 0^ consumption of potassium 

 permsnganate rises over 150 milligrams per liter, and when therefore the oxygen content 

 is low in the morning. 



Finally, a thorough liming becomes necessary after the appearance of contagious 

 diseases. Heavily stocked trout ponds are — for hygienic reasons — to be limed regularly 

 after the fishing out, and in such a manner as if disease had been present, 



Froia the fact, that for instance in the pond fishery territory of the Lusatian and 

 Lueneberg districts, the area comprises about 32 percent of the total German pond 

 industry, and from the frequent occurrence of naturally acid water, it is evident how 

 important liming is in regard to the pond industry. All other precautionary measures 

 of fertilization and pond care in such cases are completely useless if liming has not 

 been done first. Induced by the experiences of the author, Reinecker has gathered 

 extensive material in upper Lusatia upon the question — what significance lias limin g 

 in the pond industries upon heath and moor soils according to their extent. Among 60 

 investigated ponds altogether, only two had an A.C.V. of over 2, only three an A.C.V. 

 of over 1, and only eleven ponds an A.C.V. of more than 0.3. CTily once was the pH 

 value greater than 7. A yield increasing action of lime dosing cannot be expected in 

 general even in a pond water with a high A.C.Y., whose lime content has also not been 

 gradually reduced again by an acid soil with pH values below 6. In such ponds the 

 most t!;at can be achieved by liming is a general soil improving action in heavy and in 

 muddied bottoms, and a disinfecting action. Lime rich ponds with a non-mudded sand 

 bottom therefore come least into consideration for lime fertilization. 



Lime is used in the following forms: 



(1) Powdered limestone and limestone marl. Powdered limestone contains only 

 calcium carbonate, which as such is almost insoluble in water. The CO2 

 of the water will dissolve it, though — ^within about a month — into Ca 

 (HCO-3)2 Carbonated lime can be used v/here only acid fixation and 

 an increase of the A.C. value is desired and where fish life is 

 jeopardized through the caustic action of quick lime. (As in winter 

 ponds, especially with ice coverage, and trout ponds). Calcium car- 

 bonate is likewise specially used in bottom liming of light pond 

 bottoms for fertilizer purposes. Powdered limestone contains about 

 90 to 95 percent of CaC03, (100 parts of CaC03 contain only 56 parts of 

 quick lime (CaO), that is, calcium carbonate will bring only slightly 



163 



