Soil organic carbon (C-org) - importance, determination, evaluationOriginal Title (non-English) Der organische Kohlenstoff im Boden (C-org) - Bedeutung, Bestimmung, Bewertung [German]

摘要

Organic carbon is a precondition for soil formation and for the preservation of its fertility. It has a crucial importance for yield formation and for the environment, in particular for the global carbon cycle. Precision and accuracy of its determination is difficult due to the variability and heterogeneity in soil. In long-term field experiments on sandy soils the differences in soil organic carbon (C-org) between treatments 'without fertilization' and 'optimally supplied' amount partly less than 0.2% C-org. Moreover, even extreme changes in management cause annual changes of C-org of only less than 0.01%. Due to the high spatial and temporal variability the standard error of C-org is >0.1%. An evidence of the changes in soil C-org due to management requires investigations in regular intervals (annual, as far as possible) over a longer period (>20 years). At present, only the 'Humus Balance Method' (Humusbilanzmethode; VDLUFA 2004) is a reliable tool to estimate the organic matter supply in the field. Recommendations to conclude the organic matter supply level from difference of two C-org measurements are wrong and misleading. A reduction of the atmospheric CO2- concentration by carbon accumulation in arable soils is not relevant. In sandy soils only about 10% of organic amendments are accumulated.