Methods of liming

Liming can be carried out in three different ways:

        i.            By broadcast over dried pond which includes the dike walls

      ii.            By liming the water flowing into the pond

    iii.            By mixing with water and spraying over the pond

In general, any one of these methods may be employed.

By broadcast over dried pond/liming the pond bottom: Lime should be spread as uniformly as possible over the complete surface of the pond. The quantities to use for liming the bottom of a pond are very variable and depend on the aim and the nature of the soil.  

Ø    If it is for the control of parasites then 1000 to 1500 kg of CaO or 1000 kg of calcium cyanamide are used per hectare. The product is spread over soil which is still damp.

Ø    If it is to improve the soil before using other fertilizers, the ratio is 200 to 400 kg of CaO per hectare provided the pond is not acid.

Ø    If the aim is to increase the pH and alkalinity of an acid pond the quantities used vary considerably according to the degree of acidity and the nature of the soil. The recommended doses of lime for different pH values of the soils are given below:

By liming the water flowing into the pond: This method is uncommonly practiced although it saves the labor in spreading since this avoids the necessity of spreading. A lime mill placed in the water channel is used. It comprises a funnel into which the limestone or the caustic lime is poured. The bottom of the funnel can be regulated.   

By mixing with water and spraying over the pond: Lime should be spread as uniformly as possible over the complete surface of pond water. Liming the pond water is usually carried out with the use of flat boat.

If the operation is with ground limestone no special precautions need be taken.  

If quick lime is used it can be distributed up to 200 kg per hectare per day even over several days.

Nevertheless, it is necessary to keep on eye on the pH variation which might result, especially when the water is poor in calcium. The pH should not exceed 9.5.

Ref. Huet, M., (1979), Textbook of fish culture Breeding and cultivation of fish.