High Root Biomass FOR cereal crops increases carbon sequestration in organic Arable systems

Summary

In agroecosystems, soil organic carbon (C) inputs come from applied manures, plant roots and retained shoot residues. Several reasons, associated with root measurements, limit current knowledge on root C input.This study aimed at evaluating root responses to nutrient management and fertility building measures (e.g. catch crops). We made use of one inorganic fertilizer-based and two organic systems in an 11-year-old field experiment on sandy loam soil. At anthesis, soil cores (5 cm dia.) were sampled from 0-30 cm depth within and between rows of winter wheat and spring barley. Roots were separated from soil and washed with tap water, the dry matter (DM) biomass was determined. Dry matter biomass was also measured in shoots.The spring barley root DM was at least 30% higher in the organic compared to the inorganic fertilizer-based system. The organic system that included catch crops had 17% higher spring barley root DM than where catch crops were absent. In the inorganic fertilizer-based system, the biomass shoot-to-root ratio for spring barley was double that in the comparable organic system. High root DM biomass in organic compared to the inorganic fertilizer-based systems, implies higher C sequestration in the former, especially considering the slow decomposition rate of root residues.