Soil organic and inorganic carbon contents in relation to soil physicochemical properties in northeastern China
Soil carbon includes two components of organic carbon( SOC) and inorganic carbon (SIC) and, the amount of SIC in the earth surface is about half of the SOC amount (1500Pg) , showing its critical importance in global carbon balance although more studies an on SOC dynamics compared to SIC. Concurrent study on SIC and SOC will give; a more; detailed understanding on soil carbon budget than any study on either SOC or SIC alone. Based on the pooled elata from Heilongjiang Province, Liaoning Province, Jilin Province anel Inner Mongolia Autonomous Region in northeastern China, correlation analyses between variable soil physieal-chemical properties anel SOC content as well as SIC content were performde in order to find their possible funetions in affeeting those two eompetnents anel the potential influenece on soil earbon buelget cstimation in this paper. In general, a larger elatase;t for SOC (38 to 345 pairs) eompareel with those; for SIC (36 to 122 pairs) was e-ompile;el in this paper owing to SIC elata shortage. As shown by our results, signifieant anel positive correlations were found between SOC anel parameters of total nitrogen, available nitrogen, total phosphorus, available phosphorus, available potassium, exehangeable K+capaeity, Fe2O3, P2O5, total soil porosity (R2=0. 10-0.94, n = 38-345, P＜0. 0001 ) , while those for SIC were of signifie-ant negative correlations (R2 = 0. 11-0.30, n = 31-122, P＜0.01) eateept available P and available K (P＞0.05, ns) . (liven that soil fertilization could affect soil carbon dynamics, this finding indicates that most parameters of soil fertility can contrarily affect the content of SIC and SOC. Furthermore, soil pH and bulk density showed negative correlations with SOC (R2 =0. 36-0.42, n = 41-304, P＜0.0001) , but they were positively correlated with SIC (R2 =0. 29-0. 31 , n = 39-125, P ＜0. 01). As obviously manifested by these results, SOC and SIC in northeastern China were markedly correlated with most soil physical-chemical properties, but completely differed in the direction. Land utilization as well as soil management can largely affect soil physical-chemical properties and such changes have already been well-documented. For example, over 30% soil organic matter ( SOM) has been lost during the long-term agricultural reclamations and recent studies also found tens of grams of SOC per square meter per year have been accumulated after the return of degraded farmland to forests in this region, but less information is available for SIC. The contrary tendencies of SIC with respect to SOC observed in this paper indicate that inclusion of SIC in the carbon balance calculation may offset the SOC change to some degree. Therefore, in future studies of soil carbon balance, we should pay more attention to the mutual compensator}' effect between SOC and SIC, I. E. , SOC increases may indicate SIC decreases, or vice versa, and concurrent measurement of SOC and SIC may improve the precision of carbon budget estimation. The empirical equations best-fitted from this study might be used to correct previous bias shown by the lack of SIC represented in former studies. However, this mutual compensator}' effect between SIC and SOC will be more sound after long-term studies on permanent plots or well-designed fertilization experiments. Anyway, our results strongly suggest that the general neglect of SIC in current soil carbon research might produce an evident bias in calculation of total carbon budget; especially in some regions with high SIC content, such as the chernozem (a kind of black soil abundant in SIC) widespread in northeastern China.
国家科技期刊平台
NSTL
万方数据
维普
