The Efficiency of Press Mud, a Sugar Mill By-Product, as an Alternative and Cheaper Source of Phosphorus Fertilizer in Semi-Intensive Fish Culture System

Abstract

The commercial and conventional organic and inorganic fertilizers being used in Fish Culture System are usually very costly and sometimes their availability is also a big issue. Hence, there is a dire need of the time to search for alternate and cheaper sources to meet the need of the day and covering financial inflation, too. For this purpose, Sugar Press Mud (SPM), a by-product of Sugar Industry was taken into consideration to be a targeted organic Fertilizer / Manure in Semi-Intensive Fish Culture System taking Indian Major Carp, Labeo rohita (Rohu) as a selected fish. A series of experiments were conducted on SPM for its proper futuristic application to the fish ponds. These included its physico-chemical analysis; macro- and micro-nutrients profile along with heavy metal determination; temperature and pH influences on available phosphate releases from SPM and its further effects on fish survival and growth; determination of suitable application rates of SPM for Semi-intensive Fish Culture System and its comparison with other available, already in use manures like Cow dung (CD) and Poultry droppings (PD). The physico-chemical analysis of SPM samples including pH, total Alkalinity, total Hardness, Electric Conductivity and Total Dissolved Solids fulfilled the criteria for Aquaculture needs and were found in accordance with desirable ranges established by WHO, 1986; Boyd, 1990; FEPA, 1991; EPA USA, 1976 and UNECE, 1994. The multi-elemental analysis indicated that SPM contained luxuriously high amounts of macro-nutrients (N, P, K, Ca, Mg and S); moderate levels of micro-nutrients (B, Co, Cr, Cu, Fe, Mn, Mo, Na, Ni, Sr and Zn) availability along with the safer levels of toxic elements (Al, Ba, Cd, La, Li and Pb). The total and available released levels of phosphate from SPM samples at an application rate @ 8000 kg ha−1 were evaluated and found minimum at 0.01 mgL-1 to a maximum of 72.66 mgL-1 for total phosphate, respectively and from a minimum of 0.01 mgL-1 to a maximum of 4.13 mgL-1 for available phosphate, respectively. The effects of temperature and seasons on release of available phosphates trends from SPM as a Phosphate fertilizer @ 10,000 kg hac-1 at three different pH ranges i.e., 6.1-7.0, 7.1-8.0 and 8.1-9.0 in comparison with rock phosphate (RP) was evaluated. It was observed that the phosphate releases always increased periodically with high temperature in summer. However, amongst two fertilizers, press mud of sugar mills proved to be highly rich in the available phosphate-phosphorus and released it at a significantly and fairly higher rate as compared to the rock phosphate. It was further recorded that maximum release was observed in experimental aquaria fortified with press mud of sugar mills maintained at pH level 6.1-7.0. The most suitable pH ranges for efficient phosphate releases, physico-chemical suitability of water and for obtaining better survival and growth targets of Labeo rohita was also appraised which was found to be in the range 7.5-8.5. The best fertilization rates evaluation studies of SPM were undertaken which proved 8000 kg hac-1 at the first priority level followed by 10,000, 12,000 kg hac-1 while least with 6000 kg hac-1 with respect to P-PO4 release from SPM, physico-chemical suitability of water, survival and growth rates of Labeo rohita with a stocking density of 15000 Fish fry / hectare. The SPM compared in combination with Cow dung and Poultry droppings concluded that SPM (100%) was best followed by combination of SPM (67%) + CD (33%) and CD (67%) + SPM (33%) while the ranges observed in SPM (67%) + PD (33%) fertilization ratio were mostly unsuitable. The SPM feasibility in fish polyculture systems with a combination of Indian Major Carps and Chinese Carps revealed the best fish growths was shown by Hypophthalmichthys molitrix. The best survival rate was provided by Ctenopharyngodon idella followed by Labeo rohita, Catla catla, Cirrhinus mrigala and Hypophthalmichthys molitrix. On the basis of our research, Sugar Press Mud can be considered as a good optional organic futuristic Aquaculture fertilizer leading to more sustainable, economical and environment friendly systems due to its phosphates availability and nutrients recycling.