A field experiment was conducted at Central Research Farm, BARI, Gazipur (AEZ-28) and On Farm Research Division, BARI, Noakhali (AEZ-18) during Rabi season of 2017-2018, 2018-19 and 2019-20 to develop a fertilizer recommendation for chilli with garlic intercropping system. The experiment confined with intercropping where chilli was transplanted as main crop and garlic was sown as companion crop. The variety of chilli was BARI Morich-3 and Local in Gazipur and Noakhali, respectively. The variety of garlic was BARI Garlic-2 in both the location. Before conducting the experiment, initial composite soil samples at a depth of 0-15 cm from the experimental plots were collected and analyzed following standard methods.
The experiment was laid out in a randomized complete block design with three replicates. The unit plot size was 4.0 m ´ 3.0 m. Chilli transplantation and garlic cloves dibbling were done on last week of November at Gazipur and 2nd week of December at Noakhali in all the three consecutive years. One row of garlic was sown in between two rows of chilli. Line to line spacing of chilli was 40 cm and chilli to garlic spacing was 20 cm. Plant to plant spacing of chilli and garlic was 40 cm and 10 cm, respectively.
The experiment was set up with six treatments viz. T1 = 100% RDCF of chilli + 0% RDCF of garlic,
T2 = 100% RDCF of chilli +10% RDCF of garlic, T3 = 100% RDCF of chilli + 20% RDCF of garlic, T4 = 100% RDCF of chilli +30% RDCF of garlic, T5 = 100% RDCF of chilli +40% RDCF of garlic and T6 = 100% RDCF of chilli +50% RDCF of garlic. Recommended fertilizer dose was estimated based on the soil test value. At Gazipur, recommended dose of chemical fertilizer (RDCF) for chilli was N99.5 P32.6 K64 S9.5 Zn0.2 B0.9 kg ha-1and garlic was N118 P27.5 K60 S28 Zn0.5 B2.8 kg ha-1whereas the recommended doses of chemical fertilizer for chilli and garlic were N104P52 K89S1.4kg ha-1 and N127 P44 K83.6 S4B0.7Kg ha-1, respectively at Noakhali.
The whole amounts of P, S, Zn, B and 1/4th of K will be applied at the time of final land preparation. Remaining K and whole amounts of N will be applied in three equal installments at 25, 50 and 75 days after transplantation from 10-12 cm away from the base of the plant which will be beneficial for the growth and yield of garlic. Cowdung (5 t ha-1) were applied as a basal in all the plots. All the intercultural operations such as irrigation, weeding, insect control etc. were done as and when necessary.
At Noakhali, Soil salinity level was measured by using Electrical Conductivity meter Adwa (AD 310) at 15 days interval from emergence to maturity stages of the crop (Appendix Fig.1) in all the three consecutive years and similar trends were observed. Salinity level was 1.18 to 10.41 dS m-1, 1.12 to 9.75 dS m-1 and 1.15 to 8.19 dS m-1 in 2017-18, 2018-19 and 2019-20, respectively over the whole growing period. Soil salinity gradually increased up to 2nd week of April and then declined due to heavy rainfall at the later stages of the crop growing period.
Chilli was harvested five times at 15 days interval starting from 3rd week of March, at Gazipur and last week of March at Noakhali. Garlic was harvested in its maturity on 1st week of April and 3rd week of April at Gazipur and Noakhali, respectively in all the three years. Ten plants from each plot were tagged at random to take records on different agronomic parameters of chilli and garlic. Data on yield and yield contributing parameters were recorded and statistically analyzed with the help of statistical package statistics 10 (Analytical Software. Tallahassee, Fla, USA) and mean separation was tested by Duncan’s Multiple Range Test (DMRT) (Steel and Torrie, 1960). Chilli Equivalent Yield (CEY) was calculated after Bandyopadhyay, 1984:
Methods of chemical analysis:
Soil pH was measured by a combined glass calomel electrode (Jackson, 1958). Organic carbon determination by wet oxidation method (Walkley and Black, 1934). Total N was determined by modified Kjeldahl method. Ca and Mg were determined by NH4OAc extraction method. K, Cu, Fe, Mn and Zn were determined by DTPAextraction followed by AAS reading. Boron was determined by CaCl2 extraction method. Phosphorus was determined by Bray and Kurtz method (Acid soils) and Modified Olsen method (Neutral + Calcareous soils). S was determined by CaH4 (PO4)2.H2O extraction followed by turbidimetric method with BaCl2.