Carbon mineralization of corn ( Zea mays L.) and bromegrass ( Bromus inermis Leyss.) Components with an emphasis on the below-ground carbon

Abstract

Carbon mineralization of top, root and extra-root materials from 14C-labelled corn ( Zea mays L.) and bromegrass ( Bromus inermis Leyss.) was determined using 14CO 2 evolution. The mineralization curves were modelled using a double-exponential equation. Root material was also divided into coarse and fine fractions and carbon mineralization from these components was also examined. The root materials were found to be the least mineralized component of each plant at the end of the study. The coarse root fractions were found to be more quickly mineralized than were the fine root fractions. The mineralization data from root and extra-root materials were combined with data from a previous study on rhizodeposition to model the net gain or loss of rhizodepositional matter under corn and bromegrass cropping systems. The results of the carbon mineralization study and the subsequent models indicate a much greater persistence of rhizodepositional organic materials under bromegrass than under corn.