Carbon, nitrogen, phosphorus and sulphur relationships and their correlation with other soil constituents in tea soils of western Himalayas

The results revealed that most of N, P and S in tea soils was locked up in organic combinations. C/S ratio was positively and significantly correlated with organic C and negatively with clay and silt. The C/P ratio was negatively and significantly affected by total P and organic P. However, pH and organic carbon influenced the C/P ratio significantly and positively. Multiple regression revealed that 80.7 to 81.7% variation in C/P ratio was due to organic P + organic C, out of which the contribution of organic P was 61.7–65.7%, meaning thereby that organic P and organic C were the most important factors influencing C/P ratio. The C/N ratio was positively and significantly influenced by pH, organic C and negatively by silt, exchangeable Al, extractable Al, amorphous Al, extractable Fe, amorphous Fe, and crystalline Fe, among different physico-chemical properties, pH and crystalline Fe were most important which influenced the C/N ratio of the tea soils at different locations. About 65, 50 and 57% of tea soils in surface layers and 70, 50 and 60% in sub-surface layers were having wider C:N, C:P and C:N:P:S ratios and rest were having narrow ratios.