Experimental Site :
The experiment was started in 2015-2016 period at the field of Regional Agricultural Research Station (RARS) under Jamalpur district in Bangladesh. Before initiation the experiment, the soil samples were collected from a depth of 0-20 cm for each replication and analyzed following standard methods. The chemical properties of soils in the experimental site was silt clay loam in texture belonging to Sonalata series under Agro-Ecological Zone-9 (AEZ-9), 24?56´11´´N latitude and 89?55´54´´E longitude and an altitude of 16.46 m. Nutrient status of initial soil prior to fertilization is presented.
Biochar Production:
The biochar was produced using rice husk collected from local rice mill. The biochar was produced using pyrolysis method and achieved by loading the rice husk in the drum covered with a metal sheet at the top. The rice husk was burnt in the presence of little oxygen. The burnt husks were then ground and used as biochar. The chemical compositions (such as organic carbon, N, P, K, S, B, Cu, Fe, Mn, Zn, Mg, Ca and pH) of biochar were determined.
Experimental Design and Layout:
The experiment was laid out in Randomized Complete Block (RCB) design with seven treatments replicated thrice. The unit plot size was 3 m ´ 2 m. There were seven treatments viz.T1: Control, T2: Soil test based (STB) following FRG-2012, T3: (T2 –N) + Biofertilizer, T4: T3 + Biochar , T5 : STB + Biochar, T6: Only biofertilizer, T7: Only biochar
Biochar Incorporation and Rhizobium Inoculation:
A corresponding quantity of biochar was mixed thoroughly in top soil. The tested crop was groundnut (cv. BARI Chinabadam-8). Peat based rhizobial inoculum (Bradyrhizobium strain BARI RAh-892) was used containing 108 cells g-1 inoculum was used at the rate of 1.5 kg ha-1. Groundnut seeds were mixed thoroughly with the inoculum before sowing. The unit plots measured 3 m × 2 m. Seeds were used at the rate of 75 kg ha-1. Both the Rhizobium inoculants and the groundnut variety were sourced from Bangladesh Agricultural Research Institute, Joydebpur, Gazipur.
Sowing, Fertilization and Weeding:
The seeds were planted by dibbling method on 05 December, 2016. Note that, the uninoculated seeds were sown first to avoid contamination. Nitrogen, phosphorus, potassium, sulphur, zinc and boron were used in the form of urea, TSP, MoP, gypsum, zinc sulphate and boric acid, respectively. All P, K, S, Zn, B and 1/3rd urea-N were applied at the time of final land preparation and the remaining 2/3rd urea-N was applied in two equal installments at 30 and 50 days of sowing. All the intercultural operations such as irrigation, weeding, insect control etc. were done as and when necessary.
Data Collection:
Data were collected on the following parameters; plant height (cm) using meter rule, number of nut plant-1, 100-nut weight (g), kernel weight of 100-nut (g), 100-kernel weight (g) nut yield (t ha-1), tilling (%), stover yield (t ha-1). Nodule number plant-1, nodule weight (mg plant-1), root weight (g plant-1), shoot weight (g plant-1). Nodules were collected by carefully uprooting five sample plants selected randomly from each unit plot at the 50 percent flowering stage. Nodules were separated from the roots, counted and then oven-dried and weighed. Data on yield and yield components were recorded at maturity. The crop was harvested on 25 May 2017. Data on yield and yield contributing characters were recorded and analyzed statistically using statistical software STAR which was developed by IRRI. The analyzed data were compared with Least Significant Difference (LSD) test at 5% level.