Distribution of carbon, nitrogen, phosphorus, and sulfur in the soil in a multiple habitat system in India

Abstract

We measured the background level and spatial variation of carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) and associated basic soil parameters along the depth profile for 3 years, in 3 habitats (woodland, wetland, and grassland), in Keoladeo National Park (KNP), an important water fowl reserve and a world heritage site in India. The study examined soils at 5 depths (0, 0.25, 0.50, 0.75 and 1.0 m) for 3 years, i.e. from 2003 to 2005. Total organic C (TOC), total N (TN), total available P (TAP), and total available S (TAS), irrespective of the habitat type and year, were found to be highest in the litter layer, gradually declining with depth. Elemental ratios (C : N, C : P, and C : S) followed the same declining trend, whereas the N : P ratio increased down the soil profile. The high C : N and C : S ratios in the litter layer suggest the relatively low mobilisation of N and S from the decaying detritus layer. All the variables studied varied significantly among the soil layers (GLM-ANOVA, P < 0.05). Principal component analysis (PCA) showed 4 components based on examination of the scree plot. The first component accounted for 27.1% of the total variance in soil characteristics among samples, reflecting the influence of soil variables such as P, TOC, and pH. The second component accounted for 23.5% of the total variance, reflecting the influence of total dissolved solids (TDS) and TAS. The influence of C on elemental ratio (C : S) was pointed by the third component, accounted for 14.2% of the total variance. The fourth component accounted for 13.6% of the variance, indicating the influence of soil TN. Thus, the 4 PCA components that accounted for 78.4% of the total variance in the data can be qualified as N : P/soil P/C, TDS/TAS, C : S ratio, and soil TN, respectively.