Comparison of Effect of Organic and Inorganic Fertilizer on Soil Chemical Properties in Spinach Production

The research work was conducted in November 2024 at Field laboratory of Institute of Environmental Science, Rajshahi University Rajshahi to study the comparison of effect of organic and inorganic fertilizer on soil chemical properties in Spinach production. There were six treatments in this experiment. The experiment was laid out in randomized complete block design (RCBD) with three replications. Each block was compacted with a 6unit plot. Thus, the total numbers of unit plots were 18. The unit plot was 4m×1.25m = 5.0m<sup>2</sup> having plot to plot 0.5m and 1m from surrounding the boundary. The unit plots were separated with earthen bunds to avoid nutrient transfer to besides plot by lateral seepage. This study evaluated the impact of six different soil treatments (T<sub>0</sub>–T<sub>5</sub>) on the dynamics of soil organic matter (SOM), macronutrients (N, P, K), and micronutrients (S, Zn, B) from pre-cultivation to post-harvest. Results indicate that while cultivation generally leads to nutrient depletion, specific management protocols can mitigate these losses and enhance soil fertility. Statistical analysis revealed that Total Nitrogen (TN) and Available Phosphorus (P) were significantly influenced by the treatments (and, respectively). Treatment T5 emerged as the superior protocol, achieving the highest net gains in TN (+0.04%) and Available P (+2.20 mg/kg). In contrast, the control (T<sub>0</sub>) and T<sub>2</sub> experienced substantial phosphorus depletion (up to -10.02 mg/kg). A notable inverse relationship was observed between SOM and TN; while SOM decreased in most plots due to microbial mineralization, TN levels rose, suggesting a high rate of organic nitrogen conversion. Regarding micronutrients, Sulfur (S) and Boron (B) levels showed highly significant variations. T<sub>5</sub> demonstrated the best performance in minimizing Sulfur loss (-1.46mg/kg) and maximizing Zinc (Zn) accumulation (+0.08mg/kg). Although changes in Exchangeable Potassium (K) and SOM were recorded as non-significant (NS), the numerical trends consistently favored T<sub>5</sub> and T<sub>4</sub> for maintaining nutrient stability. Overall, Treatment T<sub>5 </sub>provided the most balanced nutrient profile, effectively preventing the "nutrient mining" seen in other treatments. This study recommends T<sub>5</sub> as an optimal strategy for sustaining soil health and ensuring long-term productivity in intensive cropping systems.