Proper nitrogen (N) management of high yielding rice varieties is crucial for obtaining their potential yield benefit. In this study, we compared the effect of different N rates on rice growth, yield, and N use efficiency of two high yielding rice varieties (BRRI dhan58 and BRRI dhan75) in a Boro (dry season)-fallow-T. Aman (wet season) cropping pattern. The N rates were: 0, 25, 50, 75, 100, 125, 150 and 175 kg ha −1 which were assigned in randomized complete block design with three replications. In Boro season, BRRI dhan58 showed higher response to applied N compared to BRRI dhan75 in T. Aman season. The calculated optimum N dose to maximize yield of BRRI dhan58 and BRRI dhan75 were 142 kg ha −1 and 82 kg ha −1 , respectively. The agronomic N use efficiency and fertilizer N recovery efficiency were comparatively higher in BRRI dhan58 grown in Boro season than BRRI dhan75 grown in T. Aman season, while in both seasons, the N use efficiencies decreased with increased N rates. This study results suggest that variety-specific N fertilization with respect to growing season is the best N management practice to maximize rice yield avoiding the excess use of N fertilizer.

Arsenic (As) contamination is widespread in Bangladesh. It can cause health hazards depending on consumption of foods grown on As contaminated soil. Two pot experiments were conducted at net house, Department of Soil Science, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur to study the effect of As on above ground biomass of different rice genotypes and to determine the relationship of As concentration between rice grains and straw. Sixteen rice genotypes were grown in pots soils having 0, 20, 40 and 60 mg/kg As both in winter and wet seasons. Soil As levels reduced above ground biomass of rice by 8-65%. Above ground biomass reduction was the least in BRRI dhan47 with variable soil As levels. Total As concentrations in straw and grains increased with increasing soil As levels. Moreover, the concentration of As in rice grain was also increased with greater As concentration in straw. Grain to straw ratio of As concentration was lower at higher As concentration in straw. It is indicated that reduced movement of As from rice straw to grain take place when straw As concentration was high.

Transportation is one of the main sectors contributing to greenhouse gas (GHG) emissions that cause global climate change. One of the decarbonization strategies from the transportation sector that can be implemented is by switching to a sustainable mode of transportation, especially battery electric vehicles (BEV). Since mid-2021, Obi Island has been producing Mixed Hydroxide Precipitate (MHP). It is an intermediate product of limonite nickel ore processed using hydrometallurgical processing techniques through the first refining plant in Indonesia using High Pressure Acid Leaching (HPAL) technology. The MHP will be processed into Nickel Sulfate (NiSO4.6H2O) and Cobalt Sulfate (CoSO4.7H2O), the primary precursor materials for electric vehicles. The potential GHG emissions reduction in the transportation sector from the processing of limonite nickel ore in Obi Island is 2.04 MtCO2 in 2022 to 21.02 MtCO2 in 2040 with a total accumulation until 2040 of 344.56 MtCO2.

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Nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) strongly influence rice plant nutrition. Present experiment was conducted at the Bangladesh Rice Research Institute (BRRI) farm, Gazipur in a permanent layout in wet season of 2014. Objectives of the research were to study the effects of NPKS on grain yield, plant nutrition, requirement of NPKS to produce one ton grain and to estimate the indigenous nutrient supply of the soil. BRRI dhan49 was tested with NPKS (complete), PKS (-N), NKS (-P), NPS (-K) and NPK (-S) fertilizer packages. The NPKS were applied @ 100-7-80-3 kg ha -1. Omission of each nutrient from the complete treatments significantly reduced grain and straw yields of BRRI dhan49. The highest yield reduction was recorded because of N omission followed by K. Nutrient concentration in grain and straw as well as nutrient uptakes were significantly affected by major plant nutrients. Nutrient uptake was directly related to the biomass production. About 87% of total K uptake remained in straw and thus a good K source for rice cultivation. Nitrogen, P, K, S and Zn required to produce one ton rice were 20.88, 5.04, 18.77, 2.08 and 0.07 kg, respectively. The indigenous N, P, K and S supply capacity of this soil was 37, 13, 41 and 6 kg ha -1 , respectively.