Comparative changes in water quality and role of pond soil after application of different levels of organic and inorganic inputs.

摘要

Changes in water parameters were studied in a yard experiment for 7 weeks after application of cow dung at 20, 50 and 100 t ha-1, poultry manure at 4, 10 and 20 t ha-1, feed mixture (groundnut oil cake and rice bran at 1:1) at 10, 20 and 30 t ha-1 and inorganic fertilizers at 100 kg urea+50 kg single super phosphate (SSP) ha-1, twice this dose (2x ha-1) and thrice this dose (3x ha-1). To study the role of soil in the mineralization process, each treatment was divided into two groups - one with and the other without soil substrate. Higher degree of changes in water parameters was observed at higher input levels. Both organic amendment and inorganic fertilization caused significant reduction (P<0.05) in dissolved oxygen and increase in free CO2, dissolved organic matter, total ammonia, nitrite, nitrate and phosphorus contents of water. Organic inputs significantly decreased (P<0.05) water pH and increased total alkalinity and hardness. In contrast, inorganic fertilization caused a significant increase in pH; alkalinity and hardness increased significantly in the presence of soil, but reduced in its absence. In organic input, presence of soil substrate caused significantly lower value of pH, dissolved oxygen, dissolved organic matter and phosphate-phosphorus and significantly higher free CO2, alkalinity, hardness, ammonia, nitrite and nitrate contents, compared with those in the absence of soil, revealing enhanced microbial mineralization in the presence of soil..