Nutrient recovery by rice crops as a treatment for aquaculture solid waste: crop yield, nutrient status and nutrient budgets. Technical Report CARD Project VIE/06/023
Cao, V.P., Nguyen, B.P., Tran, K.H. and Bell, R.W. (2010) Nutrient recovery by rice crops as a treatment for aquaculture solid waste: crop yield, nutrient status and nutrient budgets. Technical Report CARD Project VIE/06/023. Cuu Long Rice Research Institute, O Mon.
Waste from intensive catfish aquaculture production has become a pollutant of surface waters in the Mekong Delta, Vietnam. In the present study, the aim was to treat the solid waste from catfish ponds in the Mekong Delta by land application to padi fields so that the nutrients could be recovered by rice crops as a fertilizer substitute. A field experiment was commenced in the wet season 2007and continued for 6 consecutive rice crops using three doses of solid wastes (1, 2 and 3 tonne/ha) in combination with 1/3 or 2/3 of the recommended inorganic fertiliser rate (60N-17P-24K in wet season and 80N-17.4P-49.8K/ha in the dry season in kg/ha). Rice yields were generally similar in all treatments in each of the 6 consecutive crops, except that wet season yields declined by ?? with 1/3rd the fertiliser dose with only 1 t of solid waste. Moreover, with 3 t of solid waste ha, 1/3rd fertiliser dose gave higher yields in the dry season than with 2/3rd dose. With straw removal, generally N and K balances were positive in the wet season when yields were low, but negative in the dry season. With straw retention, all K balances were strongly positive but N balances were only positive with the higher solid waste and N fertiliser rates. Phosphorus balances were always strongly positive. Mean levels of organic C, N, available P, K and Zn increased in soils over the course of 6 rice crops. These results suggest that the fishpond solid waste replaced 1/3 to 2/3 of the fertiliser normally applied and confirmed that solid wastes from fishponds can be recycled for rice culture to mitigate pollution of waterway and reduce fertiliser costs.
|Murdoch Affiliation:||School of Environmental Science|
|Series Name:||Technical Report CARD Project VIE/06/023|
|Publisher:||Cuu Long Rice Research Institute, O Mon.|
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