Experimental site A field experiment was conducted in the Terrace Soil of Level Barind Tract (Agro-Ecological Zone - 25) at SRC, Bangladesh Agricultural Research Institute, Shibganj, Bogra during the rabi season of 2011-2012 and 2012-2013. The land was medium high land and well drained. The initial soil samples of 2011-2012 of the experimental fields were collected and analyzed.
Land preparation Land was prepared by 4-5 ploughing followed by laddering. Then plots of 3.0 m × 2.0 m were made according to the design. In between the blocks 1 m and plots 50 cm space were maintained for irrigation and drainage. Seed sowing Seeds of fennel of high yielding local variety were collected from SRC, Bangladesh Agricultural Research Institute, Shibganj, Bogra. Seed sowing was done in the last week of September in plots at 50 cm × 30 cm spacing. Fertilizer application Fertilizers were applied in plots according to the treatments. The sources of N, P, K and S were urea, triple super phosphate, muriate of potash and gypsum, respectively. A blanket dose of 3 kg Zn, 1 kg B and 5 t cowdung per ha was applied. The whole amount of cowdung, triple super phosphate, muriate of potash, gypsum and one third of urea fertilizers were incorporated in soil during final land preparation. The rest of urea was applied in two equal installments at 30 and 50 days after transplanting (DAT). Nutrient compositions of cowdung used in the experimental field were determined as shown bellow. Irrigations and drainage Flood irrigation was done for two times just after top dressing of urea. Excess water was allowed to drain out from the plots. Intercultural operations The field was intensively kept free from weed. No diseases and insects infestation was observed during the cultivation period. Treatments The fourteen treatments in combination with four levels of N (0, 30, 60, 90 kg ha-1); four levels of P (0, 10, 20, 30 kg ha-1); four levels of K (0, 25, 50, 75 kg ha-1) and four levels of S (0, 5, 10, 15 kg ha-1) were used in the present investigations.
Methods of chemical analyses Soil pH was measured by a combined glass calomel electrode (Jackson, 1973). Organic carbon determination was done by wet oxidation method (Walkley & Black, 1935). Total N was determined by modified Kjeldahl method. Ca and Mg were determined by KCl extractable method. K, Cu, Fe, Mn and Zn were determined by NaHCO3 extraction followed by atomic absorption spectrophotometer reading. Boron was determined by CaCl2 extraction method. Phosphorus was determined by Bray and Kurtz method while S by turbidimetric method with BaCl2.
Data collections Plant height was measured after harvest. The umbels were harvested several times from late February to March. Data was recorded from 10 randomly selected plants. The yield per plot was recorded and based on that per hectare yield was calculated. Statistical analysis The data were analyzed by computer using MSTAT-C Package while the mean separation was done by Duncan’s Multiple Range Test.