M. Z. Hossain, P. von Fragstein, P. von Niemsdorff and J. Heß
The use of organic wastes in agriculture plays a great role in recycling essential plant nutrients, sustaining soil security as well as protecting the environment from unwanted hazards. This review article deals with the effect of different kinds of organic wastes on soil properties and plant growth and yield. Municipal solid waste is mainly used as a source of nitrogen and organic matter, improving soil properties and microbial activity that are closely related to soil fertility. Biowaste and food waste increase pH, nitrogen content, cation exchange capacity, water holding capacity, and microbial biomass in soil. Sewage sludge contains various amounts of organic matter and huge amounts of plant nutrients. Manure is a common waste which improves soil properties by adding nutrients and increases microbial and enzyme activity in soil. It also reduces toxicity of some heavy metals. These organic wastes have a great positive impact on soil physical, chemical, and biological properties as well as stimulate plant growth and thus increase the yield of crops.
M.R. Islam, R. Zaman, M.A. Alam, M.A.A. Khan and J. Hossain
The experiment was conducted at the Regional Agricultural Research Station, BARI, Ishwardi, Pabna, Bangladesh, during 2013-2014 and 2014-2015 to introduce maize as relay crop with T. Aman rice under different agronomic practices for determine the production potentials. The experiment was design split plot with three replications. The agronomic management practices included four plant spacing viz. S1=75 cm×20 cm (66666 plants/ha), S2=60 cm×20 cm (83333 plants/ha), S3=50 cm×20 cm (100000 plants/ha) and S4=40 cm×20 cm (125000 plants/ha) and four soil management practices viz. M1=soil mulching at 25 DAE, M2=earthing up at 25 DAE, M3=straw mulching at 25 DAE and M4= without earthing up and mulching (control). Seeds were relayed by dibbling manually in 10 days before the harvest of T. Aman rice. Results showed that an increasing plant spacing increased leaf area Index (LAI), total dry matter (TDM), crop growth rate (CGR) and light energy interception (LEI). Grain yield was higher in S3 spacing (8.44 t/ha) than others (S4 8.11 t/ha, S2 7.34 t/ha and S1 6.89 t/ha). Among the soil management practices, M2 increased LAI, TDM, CGR, LEI as well as grain yield. Moreover, M2 and M1 gave similar grain yield (8.22 t/ha and 8.02 t/ha), that were significantly greater than other two soil management practices (M3 7.55 t/ha and M4 6.98 t/ha). From the economic point of view, combination of S3M1 gave better performance with gross margin of Tk. 95000/ha and BCR of 2.17. On the basis of results, S3M1 combination was suitable for growing maize under relay sowing with T. Aman rice.
Hansani N.K.S. Pathirana, Sudu H.M.P. Wimalasena, Benthotage C.J. De Silva, Sabrina Hossain and Gang-Joon Heo
The antibacterial activity of lime (Citrus aurantifolia) essential oil (LEO) and limonene was tested against seven Gram-negative and nine Gram-positive fish pathogenic bacteria isolated from cultured olive flounder, Paralichthys olivaceus (Temminck & Schlegel) in Korea. Limonene was >99% concentrated and LEO consisted of eleven chemical compounds including 56.22% of limonene. Disk diffusion assay, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests were done. LEO and limonene inhibited the growth of both Gram-negative and Gram-positive bacteria. LEO and limonene (MBC/MIC= 2-8) were both bactericidal and bacteriostatic for the strains tested. In every fish pathogenic bacteria, the inhibition zone diameter (IZD) increased in proportion to the oil concentration and the maximum effect was found at 100% (V/V) concentrations of LEO and limonene. The antibiogram pattern indicated that all the bacterial strains, excluding three strains of S. iniae (S186, S530, and S131), showed resistance to one or more antibiotics. The percentage of the relative inhibition zone diameter (RIZD %) exhibited high values at higher concentrations of all the agents. Since antibacterial activities of LEO and limonene were considerably effective against fish pathogenic bacteria, they could be used as alternatives to treat bacterial infections in aquaculture.