The solution research control toxic gases nh3, h2s in the bottom of the intensive penaeus monodon shrimp ponds on the acid sulfate soil in Ca Mau province

Abstract

    This study monitored solution to control toxic gases NH3, H2S in the bottom of the intensive Penaeus Monodon shrimp ponds on acid sulfate soil at Hamlet 8, Thoi Binh commune, Thoi Binh district, Ca Mau province, from June in 2010 to August in 2011, with 3 crops (the first crop with each experiment pond area is 4000 m2, the second and the third crop is 4800 m2 for each pond). This solution applied bio-EM (effective microorganims) and regime oxygen into bottom pond (DOd) with different level for experiment ponds. The study implemented on ponds (the control pond: ĐC, non use EM but DOd: DOd: 2-2.8 mg/L; the M0, non use EM but DOd: 3.2-4 mg/L; the M1 pond used 1 litre/800 m3/time and DOd: 3.2-4 mg/L; the M2 pond used 1 litre/534 m3/ time and DOd: 3.2-4 mg/L; the bio-EM is used with frequency 7 days/time. In the stage of preparing pond of the first crop: M1, M2 used 200 littre/pond; in the second and the third crop used 250 littre/pond). The results showed that, the M2 pond had the highest effective in treatment toxic gases NH3, H2S: NH3 ≤0.06 mg/L, H2S ≤0.04 mg/L in the water at pond bottom; NH3 ≤0.12 mg/L, H2S ≤0.06 mg/L in the water of mud; productivity was 5.9- 7.2 ton/hectare/crop, survival rate was 67- 72% and the days number of crop : 140 days; the food change rate (FCR) =1.47-1.53; the total revenue per total cost (R/C): 1.49-2.18