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Reliance on inorganic fertilizers with less or no use of organic fertilizers has impaired the productivity of soils worldwide. Therefore, the present study was conducted to quantify the effects of integrated nutrient management on rice yield, nutrient use efficiency, soil fertility, and carbon (C) sequestration in cultivated land. The experiment was designed with seven treatments comprising of a zero input control, recommended inorganic fertilizers (RD), poultry manure (PM) (5 t ha−1) + 50% RD, PM (2.5 t ha−1) + 75% RD, vermicompost (VC) (5 t ha−1) + 50% RD, VC (2.5 t ha−1) + 75% RD, and farmers’ practice (FP) with three replications that were laid out in a randomized complete block design. The highest grain yield (6.16–6.27 t ha−1) was attained when VC and PM were applied at the rate of 2.5 t ha−1 along with 75% RD. Uptake of nutrients and their subsequent use efficiencies appeared higher and satisfactory from the combined application of organic and inorganic fertilizers. The addition of organic fertilizer significantly influenced the organic carbon, total carbon, total nitrogen, ammonium nitrogen, nitrate nitrogen, soil pH, phosphorus, potassium, sulfur, calcium, and magnesium contents in post-harvest soil, which indicated enhancement of soil fertility. The maximum value of the organic carbon stock (18.70 t ha−1), total carbon stock (20.81 t ha−1), and organic carbon sequestration (1.75 t ha−1) was observed in poultry manure at the rate of 5 t ha−1 with 50% RD. The soil bulk density decreased slightly more than that of the control, which indicated the improvement of the physical properties of soil using organic manures. Therefore, regular nourishment of soil with organic and inorganic fertilizers might help rejuvenate the soils and ensure agricultural sustainability.

To characterize twenty Rhizobium strains isolated from nodules of lentil, grasspea and chickpea, an experiment was conducted in the Soil Microbiology laboratory of the Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh. The isolates were tested for growth on Congo red Yeast Extract Mannitol (YEM) agar, peptone glucose agar, and YEM agar containing Bromothymol blue (BTB). All the strains except Ls 12 absorbed Congo red dye very weekly. Except Le 2 strains, isolated from lentil showed no growth in peptone glucose agar. All the strains isolated from grasspea and chickpea showed moderate growth on this medium. All the strains were fast-growing and showed acidic reaction on YEM agar medium. Among the strains isolated from lentil, Le 1, Le 2 and Le 4 produced moderate turbidity while Le 3, Le 6, Le 7 and Le 8 produced high turbidity in YEM broth. All the strains isolated from grasspea except Ls 3 and chickpea except Ca 1 produced moderate turbidity in YEM broth medium. Strains Ls 3 and Ca 1 produced high turbidity. To assess the effect of ten of these Rhizobium isolates viz. Le 1, Le 4, Le 6, Le 8, Ls 1, Ls 2, Ls 6, Ls 7, Ca 3 and Ca 4 on growth and biomass production of rice, a follow-up experiment was conducted in the same laboratory. Root length of rice was significantly increased over control (without inoculation) due to inoculation with different Rhizobium strains. The highest root length (9.63 cm) was obtained by inoculation with strain Ls 6 isolated from lentil. All the Rhizobium strains produced significantly higher shoot length, fresh and dry biomass over control. The highest shoot length (16.50 cm), fresh biomass (138.3 mg) and dry biomass (27.75 mg) were also obtained from the strain Ls 6.

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Plant growth promoting rhizobacteria (PGPR) stimulate plant growth by producing phytohormone which enhances the growth and physiological activities of the host plant. Recently, legume bacteria (Rhizobium spp.) have been considered as a PGPR for legume as well as non-legumes and have the potential for growth stimulation. A laboratory experiment was conducted to observe the effect of PGPR and Rhizobial inoculation on seed germination, seedling emergence, growth and development of lowland rice variety MR219. The experiment was conducted under laboratory condition using filter paper in Petri dish. The design of the experiment was completely randomized (CRD) with six replicates. The PGPR strains UPMB10 (Bacillus sphaericus), Rhizobium strains SB16, UPMR1006 and UPMR1102 were used in the experiment. Seeds inoculated with those PGPR and Rhizobium strains and the Petri dish were kept in an incubator at 30 ± 2°C for 120 h. The seeds germination and other related attributes were measured. The results suggested that inoculation significantly increased the seedling emergence, seedling vigor, root growth namely root length, root surface area and volume. Among the strains, UPMB10 performed better in seedling growth and strain UPMR1006 produced profuse hair in the radical. The results concluded that PGPR and Rhizobia strain can promote seed emergence and seedling attributes which benefits the early seedling establishment and consequently the crop growth and development.