Effect of nitrogen fertilizers on water quality in paddy field [in Thailand]
Chakkaphong Choemsiri | Kasemsi Sapson
Experiments were conducted to obtain information of nitrogen fertilizers when applied to submerged soils, Nitrogen fertilizers, ammonium sulphate, ammophos and urea were applied at the same rate to the rice field with and without weed control. Water samples were collected for ammonium-N analysis on the first three days at 2 hours interval during daytime. Green algae grew very well in the fertilized plots under weed control condition. The assimilation of CO2 by algae increased the pH of the water in the plots and it was found higher than that in the unweeded plots. The water quality was affected by the kind of nitrogen fertilizer applied. The alkalinity of water of the treatment aplied with urea under weed control became higher than the others. The analysis indicated that the released nitrogen from the applied fertilizers were in the order of ammonium sulphate, ammophos and urea respectively. However, the analysis also showed high NH4+-N content in water within 48 hours after the application of nitrogen fertilizers and gradually decreased with time.
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