Accurate Estimate Of Soil Organic Carbon Storage In Henan Province Based On High-density Profiles

Storage and distribution of soil organic carbon plays an important role in the terrestrial even global carbon cycle. Many experts and scholars have adopted a different approach or a different study area to make a good attempt and research on how to estimate soil organic carbon(SOC) density and storage of the study area more accurately. This study takes Henan Province as the study area and take advantage of the technology of ArcGIS and all the soil profiles during second soil survey of Henan Province and Henan soil types blog and 1:50000 soil map of Henan to estimate the storage and density of soil organic carbon of Henan in 0~20cm and 100 cm two kinds of depth. The main contents of the study mainly include two aspects. The first is the effects of internal variability of soil among different classification levels on the estimation of regional soil organic carbon. The second is the storage and density of SOC of Henan Province in 0~20cm and 100 cm two kinds of different depths and their spatial distribution.Soil type method is a common method to estimate soil organic carbon density and storage. In general, the scale of maps used larger and more detailed, the results will be more realistic. This study took use of 1:50000 Henan soil, 3387 soil profiles and Pedological Knowledge Based Method(PKB method) getting the soil organic carbon density and storage of surface and 1 meter depth of Henan. PKB method is the method which can keep the message of soil profiles mostly in linking the soil data with soil map. This study took Nanyang as an example to study the effect of soil variability on estimating soil organic carbon storage and soil organic carbon density map expression. The results showed us two conclusions. First, soil organic storage estimated by the three methods did not show any regularity with the soil classification level from high to low. But the differences of the three estimating results became smaller as the soil classification level from high to low. Second, the PKB method is better than arithmetic mean method(Mean) and median method(Median) on estimating soil organic carbon and soil organic carbon density map expressing.This study used the independent establishment of Henan 1: 50,000 soil database, combined with the Geographic Information Technology and expertise in soil science, statistical software to estimate the surface(0~20cm) and one meter depth of soil organic carbon density and storage. The results showed that: the surface layer of soil organic carbon density in Henan Province is between 0.15 ~ 33.35 kg·m-2, with an average of 2.08 kg·m-2, organic carbon reserves 0.33Pg(1Pg = 1015g); organic carbon density of 1 m depth is 0.31 ~ 84.87kg·m-2, with an average of 5.96 kg·m-2, organic carbon reserves 0.95 Pg. Combined with topography and climate and other factors of Henan analyzed the soil organic carbon density spatial distribution and latterly took the results compared with the estimated results of national scale and other provinces scale. The results showed that: Henan soil organic carbon density in 0 ~ 20 cm depth and 1 meter depth were lower than the national average, and soil organic carbon density affected by the terrain, climate and land use types and so on factors quite dramatically.