ICAR-Central Research Institute for Dryland Agriculture, Hyderabad-500 059, Telangana
Measurements of soil properties based on 2 mm sieved soil and expression on quantitative areal basis such as kg/ha, Mg/ha without accounting for coarse fragments can lead to inflated measurements in soils with significant coarse fragment (> 2 mm) fraction. The differences in stocks of soil organic carbon, available nitrogen and available phosphorus with and without accounting for coarse fragments in a sandy loam Alfisol with abundant coarse fragments is elucidated in this article using data from a field experiment conducted at Hayathnagar, Hyderabad, India. There was a considerable short range spatial heterogeneity in volumetric coarse fragment fraction in the soil of the experimental field of size 37 m x 29 m. The proportion of coarse fragments by volume across 21 small plots (8 m x 4 m) in the field ranged from 3.16% to 33.67% with a mean of 11.98% in the 0-20 cm depth and 4.21% to 30.52% with a mean of 18.56% in the 20-40 cm depth. Averaged over all the experimental plots in the field, the total stocks of organic carbon, available nitrogen and available phosphorus up to a depth of 40 cm were overestimated by 34.38%, 33.74% and 28.49% respectively when the volumetric coarse fragment fraction was not accounted for. The results emphasize the need to account for coarse fragments larger than 2 mm for more accurate and realistic determination of stocks of organic carbon and nutrients in soils with abundance of coarse fragments.
Soil organic carbon, Nitrogen, Phosphorus, Stocks, Coarse fragments, Overestimation
