IMPACT OF NITROGEN FERTILIZER AND COMPOST INCORPORATION ON pH AND pH BUFFERING CAPACITY OF NON-CALCAREOUS SOIL

Abstract

Non-calcareous soils are a significant component of Bangladesh's diverse soil landscape, particularly in the northern regions where agricultural practices are integral to the economy characterized by low calcium carbonate concentrations, these soils are prone to acidity, impacting nutrient availability and crop yields. The escalating use of nitrogen (N) fertilizer and compost raises concerns about potential soil acidification. This study aims to comprehensively assess the impact of nitrogen fertilizer and compost on soil pH and pH buffering capacity in non-calcareous soils. Specific objectives include examining the effects of these inputs on soil pH and buffering capacity and investigating key driving factors influencing these parameters. To fulfill the objective of the research, a lab-based experiment was designed in the laboratory of the Department of Soil Science of Hajee Mohammad Danesh Science and Technology University, Dinajpur. A 40-days incubation study was conducted. The treatments were 1) Soil (Control), 2) Soil+ 300 mg N as urea (H-Urea), 3) Soil+ 150 mg N as urea (L-Urea), 4) Soil+ 300 mg N as compost (H-Compost), 5) 150 mg N as compost (L-Compost), 6) Soil+ 300 mg N as urea + 150 mg N as compost (H-Urea + L-Compost), and 7) Soil+ 150 mg N as urea + 300 mg N as compost (L-Urea + H-Compost). The treatments were replicated three times in a complete randomized design. Soil samples were subsampled at 5, 10, 15, 20, 25, 30 and 40 days after the start of the experiment. At each subsampling, pH measurement was taken. The result revealed that pH was increased rapidly by the incorporation of urea fertilizer and combined use of H-Urea+ L-Compost. Lowest was found in control treatment. The highest pH buffering capacity was found in the treatment of H-Compost and lowest in H-Urea treatment. Organic matter was found the highest 3.20% in L-Urea+ H-Compost and the lowest in high urea treatment. The highest cation exchange capacity was found in L-urea+ H-compost and the lowest was in control treatment. Total base cation was highest in the L-Urea+H-Compost and lowest in the control treatment. The Ca, Mg, K and P were also found highest in treatment L Urea + H-Compost. In case of Na and total N%, treatment H- compost had the highest value. Therefore, it is recommended that the application of higher compost and lower urea can increase the pH buffering capacity, nutrients availability and reduced soil acidity.