Effective carbon sequestration in Italian agricultural soils by in situ polymerization of soil organic matter under biomimetic photocatalysis

Abstract

Facing an exploding population growth with consequent increase of agriculture intensification, new chemical technologies are being sought to limit organic matter losses and reduce land degradation. Here, we report that an effective organic carbon sequestration in different cropped soils of Italy is obtained by an in situ photo‐oxidative coupling among soil humic molecules, when catalyzed under solar irradiation by a water‐soluble biomimetic iron‐porphyrin catalyst amended to field soils. A 3‐year long field study showed that the catalyst‐assisted in situ photochemical polymerization of humic matter enabled a yearly sequestration of soil organic carbon that ranged from 2.2 to 3.9 t ha−1 y−1, despite the periodical soil disturbance due to a conventional tillage management. This significant stabilization of organic matter was observed not only in bulk soils but also in water‐stable aggregates, whose loss of organic carbon during separation was limited in catalyst‐treated soils. Although crop yields were the same in treated and control soils, measurements of phospholipids fatty acids and soil enzyme activities indicated that the catalyzed in situ photo‐oxidative coupling of humic molecules did not alter the structure and activity of microbial communities and the biological functions of soils. This innovative and ecologically safe catalytic technology may be developed as a useful soil management practice to stabilize organic matter in situ in arable soils, while concomitantly ensuring soil functions and sustainability of crop production.

Organic Carbon Sequestration in Soil Humic Substances As Affected by Application of Different Nitrogen Fertilizers in a Vegetable-Rotation Cropping System

“…In all the HS of N-fertilized soils, the relative percent of aromatic-C tended to increase (Table ), showing N fertilization promoted OC sequestration in aromatic-C. Combined with higher A/A ratio found in HA and HU (Figure ), N fertilization also enhanced aromaticity of HA and HU and therefore the stability of SOC . As a result of N fertilization, the ratios of A/O and HB/HI in HA and HU were improved, showing higher humidification and hydrophobicity degrees.…”

Amendments with humified compost effectively sequester organic carbon in agricultural soils

“…As a fight against land degradation, there is a rising attention in developing innovative SOM management practices that enhance content and quality of soil humus without reducing crop yields (Piccolo et al, ). A particular focus is on amending soil with highly humified compost either alone (Spaccini & Piccolo, ) or co‐processed with metal nanoparticles (Zeng et al, ; Zhang et al, , ).…”

Long‐term fertilization alters microbial community but fails to reclaim soil organic carbon stocks in a land‐use changed soil of the Tibetan Plateau

“…Land‐use changes from grasslands or forests to croplands have increased the world's productivity of grain harvests in the last century, thus ensuring food for an increasing population. This intensive land exploitation has occurred at the cost of SOC depletion and increasing annual total CO 2 emissions (Piccolo et al, ). It has also been proposed that land‐use changes from grasslands or forests to croplands induced a transformation in SOC and a shift in soil microbial communities (Kumar & Ghoshal, ; Zhang et al, ).…”