The field experiment was conducted at the experimental field of Regional Agricultural Research Station, BARI, Cumilla during 2019-20 using high yielding tomato variety (BARI Tomato-15). The study area was under AEZ-16 (Middle Meghna River Floodplain). The soil of the experimental site is Non-Calcareous Grey Floodplain Soil. The top soils are slightly acidic. General fertility level was medium with low N and organic matter content.
The experiment was laid out in randomized complete block design with 7 treatments replicated 3 times. The treatments were: T0: N-control, T1: 100% Recommended dose (RD) of N as prilled urea (PU), T2: 100% RD of N as Neem coated urea (NCU), T3: 100% RD of N as Di-ammonium phosphate (DAP), T4: 125% RD of N as PU, T5: 125% RD of N as NCU, T6: 125% RD of N as DAP. Recommended dose of N for Tomato was 120 kg ha-1. Blanket dose of 30-40-15-2-1 kg ha-1 of P-K-S-Zn-B (FRG’2018) and decomposed cowdung (10 t ha-1) were applied as basal dose.
The characteristics of nitrogenous fertilizers used in the experiment are presented. Three splits of nitrogenous fertilizers were applied as per treatment at 15, 30 and 45 days after transplanting. The seeds of above-mentioned tomato variety were sown on 25 October, 2019. Thirty days old seedlings were transplanted in the main plot on 25 November, 2019. Gap filling, plant protection, irrigation and other intercultural operations were done as and when necessary. Data on yield and yield attributing parameters were recorded from 5 representative plants. Data on 50% flowering, plant height, number of fruits/plant, weight of fruit/plant, individual fruit weight, yield/plant were recorded. Date of 50% flowering was 19 December, 2019. Collected data were analyzed by analysis of variance (ANOVA) and least significant difference (LSD) tests among means were conducted for each character separately using “Statistics-10” a statistical tool and comparison of means for the individual treatments was done at 5% level of probability based on F-test of the analysis of variance (Steel and Torri, 1980).
Nutrient use efficiency :
Agronomic use efficiency refers to the increase in crop yield per unit of an applied nutrient. It can be calculated as follows:
AE = (YNA-YN0)/NRN
Where,
AE : Agronomic efficiency
YNA : Yield (kg ha-1) due to nutrient addition
YNO : Yield (kg ha-1) due to nutrient omission
YRN : Rate of nutrient addition (kg ha-1)
Methods of chemical analyses:
Soil pH was measured by a combined glass calomel electrode (Jakson, 1958). Organic carbon was determined 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 method followed by AAS reading. Boron was determined by CaCl2 extraction method. Phosphorus was determined by Bray and Kurtz method (Acid soils). S was determined by CaH4 (PO4)2.H2O extraction followed by turbidimetric method with BaCl2.