Mucilage from fruits/seeds of chia (Salvia hispanica L.) improves soil aggregate stability

Abstract

Background and aims: Myxodiaspores have been shown to enhance soil-seed contact and improve soil stability. We aim to demonstrate the effect of myxodiaspory on the stability of soil aggregates and gain insight on the nature of bonds. Methods: Mucilage extracted from chia (Salvia hispanica L.) fruits after hydration was mixed with three soils (sandy-loam, loam, clay loam), incubated and tested at different times up to 30 days. We measured aggerate stability by wet sieving and the dynamics of soil CO2 evolution. SEM imaging and 13CPMAS spectroscopy of mucilage were performed in order to infer mechanisms of soil stabilization. Results: The incorporation of mucilage resulted in a dose- and soil-dependent rise in aggregate stability. The dose of 2% mucilage overcame textural effects on soil aggregate stability by providing a 2.3-fold stability increase in the loam and clay-loam and a 4.9-fold increase in the sandy-loam compared to control. The effect persisted after 30 days in spite of C losses due to soil respiration. Mechanisms of soil bonding analogous to xanthan can be inferred from SEM imaging and 13C–CPMAS, since the mucilage was identified as a biopolymer containing 93.39% carbohydrates and 22.02% uronic acids. Conclusions: We demonstrate that mucilage extruded by hydrated diaspores strongly increases soil aggregate stability. This represents a potentially important ecosystem service provided by myxodiasporous crops during germination. Our findings confirm potential applications of mucilage from myxodiaspores as natural soil stabilizers.