Mustard (Binasarisha-9) was evaluated against four Zn levels (0, 3, 6, 9 kg Zn ha-1) and three B levels (0, 2, 4 B ha-1) at Madhupur under AEZ 28. The results revealed that there was a significant improvement in the growth and seed yield with increasing level of B and lower Zn levels, respectively. The highest B level        (4 kg ha-1) and lower Zn level (3 kg ha-1)  resulted 96 cm plant height, 5.33 branches plant-1, 86.33 siliqua plant-1, 7.33 cm siliqua length, 28.33 seed siliqua-1 and 1633.30 kg seed ha-1. It is suggested that for achieving higher seed yields in mustard, the Zn application may be done at the rate of 3 kg ha-1 and with B of 4 kg ha-1.

Key words: Boron, Zinc, yield and mustard 

Introduction: The soil of Bangladesh has wide variation and complexity due to diverse nature of physiography, parent materials, land type, drainage conditions and agro ecology. Depending on these aspects, the country has been divided into 30 agro ecological zones (AEZ), which varied greatly in respect of area, land and soil, climate, and cropping intensity (FAO-UNDP, 1988). Some AEZs are very potential for crop agriculture and nutrient supplying capacity but some are being depleted due to intensive cropping. Madhupur Tract (AEZ 28) is one of them. The present study was concentrated to this AEZ which is a region of complex relief and soils are developed over the Madhupur clay. The landscape comprises of level upland, closely or broadly dissected terraces associated with shallow to broad deep valleys. Eleven general soil types exist in the area of which Deep Red Brown Terrace, Deep Red Brown Terrace soils and Acid Basin Clays are the major ones. The soils on the terrace are better drained, friable clay loams to clay overlying friable clay substratum at varying depths. Soils in the valleys are dark grey heavy clays. The top soils are mainly very strongly acidic in reaction but ranges up to slightly acidic with low to medium status of organic matter, low moisture holding capacity and low fertility level. The soils are mainly phosphate fixing low to medium in P, B and K; and medium to optimum in S content. The major land type comprises 56% highland and 18% medium highland (FRG, 2018). Texturally the soils are loam and sandy loam. Over the last 2-3 decades, enormous pressure has been exerted on the soil resource to produce more food for its population. Intensification of agricultural land use has increased remarkably and the cropping intensity has increased from 143% in 1971-72 to about 197% in 2016-2017 (Krishi Diary, 2021). In addition, cultivation of high yielding varieties for all crops has increased remarkably. Consequently, this has resulted in deterioration of soil fertility with emergence of micronutrient deficiency. In this country, chronologically N, P, K, S, Zn and B deficiencies have appeared in soils and crops of Bangladesh (Islam, 2008). Among the micronutrients, next to zinc, boron deficiency is prominent in soils of Dinajpur, Rangpur, Bogra, Sirajganj, Mymensingh, Comilla and Sylhet district (SRDI, 2010). The use of chemical fertilizers as the supplemental source has been increasing steadily but these are not applied in balanced proportion. Of the total fertilizer used in the country, urea alone constituted about 75% (FRG, 2012). Previous study indicated that about 60% cultivable land of Bangladesh is deficient in N, P and K (Miah et al., 2008). Moreover, organic matter content in country’s soils is low, the majority being below the thresh hold level (1.5%) and it was gradually depleted by 5 to 36% during the period of 1967-1995 (Ali et al., 1997). Islam (2008) mentioned that organic matter content in Bangladesh soils is generally around 1% in most and around 2% in few soils.