Field experiment:Thirty experimental plots (2.2 m×2.2 m) separated by 0.5 m margins were prepared in three adjacent blocks in the crop field of the Department of Soil Science, University of Chittagong. There were ten plots in each block for the ten treatment combinations comprising of poultry manure (PM), household waste compost and inorganic fertilizers- T1 (Control), T2 (Full NPK @ 120 kg N ha-1, 60 kg P ha-1 and 80 kg K ha-1), T3 (Full Compost @ 30 t ha-1), T4 (25% NPK+75% compost i.e. 30 kg N ha-1, 15 kg P ha-1 and 20 kg K ha-1+ 22.5 t ha-1 compost), T5 (50% NPK+50% compost i.e.60 kg N ha-1, 30 kg P ha-1 and 40 kg K ha-1+ 15 t ha-1 compost), T6 (75% NPK+25% compost i.e. 90 kg N ha-1, 45 kg P ha-1 and 60 kg K ha-1+7.5 t ha-1 compost), T7 (Full PM @30 t ha-1), T8 (25% NPK+75% PM i.e. 30 kg N ha-1, 15 kg P ha-1 and 20 kg K ha-1+22.5 t ha-1 PM), T9 (50% NPK+50% PM i.e.60 kg N ha-1, 30 kg P ha-1 and 40 kg K ha-1+15 t ha-1 PM), T10 (75% NPK+25% PM i.e. 90 kg N ha-1, 45 kg P ha-1 and 60 kg K ha-1+7.5 t ha-1 PM). The treatments were arranged according to a randomized complete block design.
Soil was collected from each plot before sowing seeds, after one month of sowing seeds and after harvest.
Determination of soil properties: Soil texture was determined by hydrometer method (Day, 1965), pH in a 1:2.5 soil:water suspension with glass electrode pH meter, organic carbon by wet-oxidation method (Walkley and Black, 1934), total nitrogen by micro-Kjeldahl digestion and distillation, available phosphorus by Bray and Kurtz-II method (Bray and Kurtz, 1945) and exchangeable potassium, calcium and magnesium by 1N NH4OAC saturation (Jackson, 1973).
Determination of nutrient uptake by maize: Oven dried (650C to constant weight) and ground plant samples were digested with a mixture of H2SO4, H2O2 and lithium sulfate for the determination of N, P, K, Ca and Mg in the plant tissues (Allen et al., 1986). The concentrations of Ca and Mg in the digest were measured by atomic absorption spectrophotometer (Varian nov AA). Micro-Kjeldahl method as described by Jackson (1973) was used for the determination of nitrogen. Phosphorus was determined by vanadomolybdo phosphoric yellow colour method in nitric acid system according to Jackson (1973). Potassium was measured by flame photometer. Nutrient uptake was calculated from the nutrient concentrations obtained from the tissue analysis.
Statistical analysis: The significance of differences between the means of the treatments was evaluated by one way analysis of variance followed by Duncan’s Multiple Range Test at the significance level of 5%. The statistical software Excel (Excel Inc., 2003) and SPSS version 12 (SPSS Inc., 2003)] were used for these analyses.