Effects of Different Proportions of Oyster Shell Powder on Cation Exchange Capacity and Organic Matter Content in a Sandy Regosols

Nutrient leaching, the loss of essential elements from the soil due to water percolation, is a major challenge in sandy regosols, which have poor water and nutrient retention. This low fertility hampers crop cultivation, but using oyster shell powder (OSP) as a soil amendment offers a promising solution to enhance soil quality. This study was conducted at the Soil Science laboratory, Eastern University, Sri Lanka (EUSL), from August to October 2023. The aim was to explore the impact of varying proportions of OSP on the cation exchange capacity (CEC), pH, and organic matter content (OM) of sandy regosols. Five treatments were used in the experiment: T1 (control, no OSP) and T2 to T5, which contained 0.6%, 0.7%, 0.8%, and 0.9% OSP by weight, respectively. The study was conducted with four replicates in a Completely Randomized Design. Results demonstrated that the addition of OSP significantly (P<0.05) improved the CEC (23.65 Meq/100 g), pH (9.3), and OM (0.891%) of the soil, with the highest increases observed in T5 (0.9% OSP). An enhanced cation exchange capacity (CEC) indicates improved nutrient retention, while an increase in pH suggests reduced soil acidity, which is beneficial for nutrient availability. Furthermore, the increased OM underscores OSP's potential to improve soil structure and fertility. These findings highlight the value of OSP as a sustainable soil amendment, offering a viable approach to enhance the soil quality and agricultural productivity in Sandy regosols.