Production of biofertiliser from soybean cake and soypod

Abstract

Soil fertility can be improved by the use of fertilizer, which can either be of chemical or biological sources. However, the excessive use of chemical fertilizers has caused a large number of environmental pollutions in water, air and soil. This research aimed to produce organic fertilizer from soybean cake and pod using Solid State Fermentation (SSF). Soybean cake and pod samples from WASIL Oil Company, Sagamu, Nigeria underwent NaOH pretreatment for delignification. Physico-chemical parameters including temperature, TDS, moisture content, pH, phosphate, potassium, calcium, nitrate, and sulphate were analyzed using standard methods. Microbial populations were determined through agar plate and broth culturing, while SEM, FTIR, and EDX analyses were conducted on raw and pretreated samples. Results showed that for soybean cake, temperature was 28.50°C, TDS 34.9mg/l, moisture content 58.4%, pH 7.56, phosphate 2.81mg/l, potassium 2.50 mg/l, calcium 38mg/l, nitrate 2.69 mg/l, and sulphate 32mg/l. For soybean pod, values were 28.40°C, 33.1mg/l, 51.2%, 7.06, 2.90mg/l, 2.8mg/l, 41mg/l, 2.84mg/l, and 36mg/l respectively. Microbial counts for soybean cake included Salmonella (2.4 x 10?), E. coli (2.1 x 10?), Bacillus (2.7 x 10²), and Aspergillus (3.7 x 10²), while soybean pod showed Salmonella (1.9 x 10?), E. coli (2.1 x 10?), Bacillus (2.4 x 10²), and Aspergillus (3.4 x 10²). SEM revealed irregular morphological shapes at surface layers. FTIR confirmed presence of amine and carboxyl groups indicative of fertilizers, while EDX detected nitrogen, phosphorous, and other nutrients. The study concluded that SSF is suitable for producing effective and economical organic fertilizer from soybean cake.