Lucas, M., J. P. Santiago, J. Chen, A. Guber, and A. Kravchenko. 2023. The soil pore structure encountered by roots affects plant-derived carbon inputs and fate. New Phytologist 240:515-528.

Plant roots are the main supplier of carbon © to the soil, the largest terrestrial C reservoir. Soil pore structure drives root growth, yet how it affects belowground C inputs remains a critical knowledge gap. By combining X-ray computed tomography with 14C plant labelling, we identified root?soil contact as a previously unrecognised influence on belowground plant C allocations and on the fate of plant-derived C in the soil. Greater contact with the surrounding soil, when the growing root encounters a pore structure dominated by small (<?40??m ?) pores, results in strong rhizodeposition but in areas of high microbial activity. The root system of Rudbeckia hirta revealed high plasticity and thus maintained high root?soil contact. This led to greater C inputs across a wide range of soil pore structures. The root?soil contact Panicum virgatum, a promising bioenergy feedstock crop, was sensitive to the encountered structure. Pore structure built by a polyculture, for example, restored prairie, can be particularly effective in promoting lateral root growth and thus root?soil contact and associated C benefits. The findings suggest that the interaction of pore structure with roots is an important, previously unrecognised, stimulus of soil C gains.

DOI: 10.1111/nph.19159

Associated Treatment Areas:

• GLBRC Marginal Land Experiment

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