Impact of Soil Suitability Class, Variety, Milling Method, and Ageing Status on Some Chemical Properties of Coco Pith

Given that coco pith is a versatile growing medium, understanding the factors that influence its physicochemical properties is crucial for optimizing its use. This study examines how soil suitability class, coconut variety, milling method, and ageing status affect electrical conductivity, pH, and the concentrations of Na⁺ and K⁺ in coco pith. Husks from Tall×Tall (TT) and Dwarf×Tall (DT) varieties were processed using dry and wet milling methods, with and without ageing, across 43 blocks representing different soil suitability classes. Results showed that milling method significantly (P<0.0002) influences electrical conductivity, with dry milling producing higher conductivity (1887.07 μS cm^-1) than wet milling (1337.25 μS cm^-1). Ageing markedly reduced electrical conductivity (P<0.0001), and no significant differences between milling methods were observed for aged coco pith. A three-way interaction between variety, milling method, and ageing status influenced pH (P=0.0007). DT variety processed via dry milling exhibited higher pH values (6.6±0.1), while wet milling consistently yielded lower pH (6.3±0.1). Aged coco pith had an average pH of 6.4, slightly lower than the 6.7 of non-aged pith. Soil suitability class also impacted pH, with S2 showing the lowest (6.4) and S₄ the highest (6.7) (P<0.05). Na⁺ levels were significantly reduced in aged coco pith across all combinations due to enhanced particle breakdown (P=0.0488). Both milling method and ageing status affected K⁺ levels (P<0.0001), with ageing leading to reduced concentrations. These findings underscore the importance of ageing and milling methods in improving coco pith quality by optimizing its chemical properties.