Biochar for Improving Growth Performance of Shrimp and Environmental Quality in an Inland Saline Culture System

The current study, which lasted 45 days, was designed to find a more effective way to use the vast resources of salt-affected land and ground saline water for aquaculture. Biochar made from agrowaste was used as a sediment amendment. The 100 g of biochar was applied to 25 kg of sediment (i.e., 9.0 ton ha^-1) in 300L capacity fiber reinforced plastic, and Penaeus vannamei (P. vannamei) (2.74 ± 0.03 g) was stocked at 90 juveniles m^-2 in inland ground saline water of salinity 10 ppt fortified with potassium levels that are 50% equivalent to those of seawater. Among different treatments, T1 indicates paddy straw biochar (PSB) application in sediment; T2 indicates sediment amended with KOH-activated PSB; T3 indicates sugar cane bagasse biochar (SBB) application in sediment; and T4 indicates sediment amended with KOH-activated SBB. Compared to the control the potassium (K⁺), alkalinity, total hardness, calcium/magnesium ratio, and pH of the water increased significantly (P ≤ 0.05) in treatments where biochar was used as an amendment in sediment. The T3 treatment had the best Ca/Mg ratio (1.00:3.12). In water, the magnitude of increase in K⁺ concentration from high to low followed the order: T2 > T4 > T1 > T3 > control. The concentration of NH₄⁺-N in water was found to be increasing in control, whereas in the rest of the treatments, it decreased significantly from day 1, until the end of the experiment. Compared to control, the bulk density was decreased, and sediment cation exchange capacity and water holding capacity were increased significantly in treatments where biochar was used as an amendment. The soil microbial parameter measured in terms of soil enzyme dehydrogenase was significantly different among treatments at the end of the experiment. Weight gain (%), specific growth rate (SGR), survival (%), and feed conversion ratio of P. vannamei varied significantly in T1, T2, T3, and T4 compared to the control. The SGR (2.38^b ± 0.05% day^-1) and weight gain (%) in T2, and survival (96.1^b ± 2.0%) in T3 treatment were found to be the highest at the end of the experiment. When biochar was mixed with sediment in the inland saline system, an improvement was seen in sediment quality, water quality, and growth characteristics of P. vannamei.