ABSTRACT
This chapter addresses one of the uncertainties in areal organic carbon estimates: The importance of the amount of organic carbon that is not measured in the standard depth of sampling for agricultural purposes for soils formed in deep alluvium. The study area is the Nemaha River Valley located in and considered representative of Major Land Resource Area (MLRA) 106, which is located in southeast Nebraska and Northeast Kansas. The alluvium in the Nemaha Valley averages about 10 to 15 meters in thickness and generally overlies bedrock. Evaluation of the amount of organic carbon in MLRA 106 involved a number of steps and considerations. Numerical estimates were made by application of an MLRA 106 map unit legend prepared in 1990. The results show that the proportion of the organic carbon in alluvium below 1.5 m is a significant part of the total organic carbon in MLRA 106.
