Living almost 15 years in karst has allowed me to know the particularities of its soils, its diversity. For that reason, when I see the maps of soil organic carbon content I am horrified to see such great mistakes made by my colleagues, the same feeling causes me to hear or read that the Yucatan peninsula, is the largest store of organic carbon in the soil in Mexico.
The organic carbon inventories in the soil in karst areas should be done in a very different way to the way they are being carried out. Discontinuity and spatial heterogeneity should be taken into account at short distances of meters. Soil bulk Density data must be generated and the soil depth not to be used beyond the real depth.
The summary of the paper is:
The organic carbon stock in Leptosls with discontinuous distribution in the Peninsula of Yucatan
The SOC estimation requires quantifying the coarse fraction(stones and gravels), bulk density and depth. The soils inventory realized for INEGI didn´t reports the first two parameters, then, the generated SOC maps have considerable doubt SOC.
The objective was to evaluate the spatial variability of soil organic carbon over short distances, as well as to report the contents of organic carbon per unit area in Leptosols from northern of Yucatan Peninsula.
102 samples were taken; organic carbon was analyzed by technique of potassium dichromate; and coarse fragments (coarse gravel, medium and fine gravel) were separated from the fine earth. The Color was recorded dry and wet, bulk density was measured using the amount of fine earth in a volume of 10×10 cm surface by a depth to find the rock.
Leptosols presented SOC values below 100 t ha-1 reported for this area, with mean values of 32.85, 37.57, 43.72, and 61.93 t ha-1, for dark brown soils, very dark brown, blacks and very dark grays respectively. Coarse fragments ranging from 6.7% to 96.4% with an average of71.15%.
The amount of edaphic organic carbon is in agreement with the values reported in percentage but lower than those reported in unit of surfaces, which is why it is being overestimated.
The spatial analysis of the soils at short distances reveals a high discontinuity and variability in the percentage of carbon, as well as in the depth and quantity of coarse fragments.
The comparison in the COS content between soils should consider the spatial discontinuity and the amount of COS in kilograms per hectare.
In the soil organic carbon inventories in the north of the Yucatán Peninsula, there has been an overestimation of the organic carbon of the soil that must be corrected considering the discontinuity of the soil and its shallow depth.
Delgado C, Bautista F, Calvo-Irabien LM, Aguilar-Duarte Y y Martínez-Tellez J. 2017. El carbono orgánico en Leptosols con distribución discontinua en la península de Yucatán. Ecosistemas y Recursos Agropecuarios. 4(10): 31-38.