Abstract:
Nutrient leaching is a phenomenon, where essential elements that important for the plant
growth are lost from the soil with percolating water through the soil profile. Sandy regosols
are characterized by inadequate water and nutrient retention, which poses significant
challenges in crop cultivation. To address the shortcomings of low-fertility soils, the
application of oyster shell powder (OSP) as a soil amendment is a viable solution to
enhanced soil quality. This natural product offers several benefits to soil health, including
enhanced pH balance and increased nutrient levels. This study was conducted to determine
the effects of different proportions of OSP on phosphorus retention in a sandy regosol. An
indoor leaching column experiment was carried out at the Soil Science Laboratory, Eastern
University, Sri Lanka. The experiment consisted of five treatments, such as the control
without OSP (T1) and 0.6% (T2), 0.7% (T3), 0.8% (T4), and 0.9% (T5) of OSP amendment
by weight. Urea, Triple Super Phosphate and Muriate of Potash were used as recommended
chemical fertilizers. All the treatments were replicated four times in a Completely
Randomized Design. The leachate was measured for phosphorus (P) from four leaching
cycles within two months period. At the end of the study, available P content in soils was
measured. Statistical analysis and mean separation were done by Turkey test at a 5%
significance level. The leachate analysis indicated the absence of phosphorus in the OSP
treated treatments due to the formation of compounds such as Ca3(PO3)2 and
Ca4.885(PO4)3(OH)0.654. And also, the available P content was significantly high in soils
where OSP was added in higher proportions due to the solubility of the insoluble phosphate
compounds by the action of microorganisms. Results revealed that T5 demonstrated the
highest P retention capacity, highlighting the potential of oyster shell powder as a soil
amendment.
