Pond Fertilization Regimen

ABSTRACT

Pond fertilization has assumed an important role to supplement nutrient deficiency and augment biological productivity through autotrophic and heterotrophic pathways. This is especially important in the extensive and semi-intensive culture systems by promoting the functioning of natural ecosystems in a benign environment. The composition of inorganic and organic fertilizers forms the basis for selection of dose and quality of fertilizer application. While inorganic fertilizers produce perceptible results within a short period, organic manure is extremely cheap and is of considerable significance in developing countries. Nitrogen demand in fish ponds can be compensated through nitrogen fixation, as well as from accumulated humus from bottom sediments, especially from old fish ponds. The frequency of fertilizer application should be economical, though it is accepted that the lower the frequency, the better the productivity. In aquaculture ponds, the optimum N:P ratio was suggested between 4:1 to 8:1, whereas the optimum C:N ratio for composting was between 20 and 40. The exchange properties and equilibrium phosphorus concentration between soil and water influence water quality, nutrient status, and primary productivity of the pond ecosystem. These act as buffers to stabilize environmental conditions in ponds. Pond soils may exert negative influence on aquaculture production if one or more of their properties are outside the optimum range for aquaculture. The present study reviews state-of-the art pond fertilization in relation to the role of pond soils; different inorganic fertilizers such as phosphorus (P), nitrogen (N), potassium (K); fertilizer dose and frequency; P:N ratio; organic manure; aquatic food web; optimal manuring; decomposition of organic manures; mineralization; production efficiency; and limitations of organic manures. More studies on pond fertilization in the context of nutrient dynamics and fertilizer-microbial interactions under different agroclimatic regions are necessary for an effective, appropriate, and economic fertilization program. The environmental consequences of overfertilization resulting in pollution and subsequent hazards to public health should be taken into consideration.

Key Words:

• Pond fertilization
• organic manures
• inorganic fertilizers
• qauatic food web