This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ldr.2989 This article is protected by copyright. All rights reserved. The molecular dynamics of soil humus as a function of tillage Marios Drosos*, Alessandro Piccolo* Centro Interdipartimentale di Ricerca sulla Risonanza Magnetica Nucleare per l'Ambiente, l'Agroalimentare ed i Nuovi Materiali (CERMANU), Università di Napoli “Federico II”, via Università 100, 80055 Portici, Italy Corresponding Authors * Phone: +39-081-25-39160; Alessandro Piccolo e-mail: alessandro.piccolo@unina.it; Marios Drosos e-mail: drosos.marios@gmail.com ORCID Marios Drosos: 0000-0003-0403-7014 Alessandro Piccolo: 0000-0002-5779-8581 Keywords: SOM; Humic Molecules; Organomineral Complexes; Humeomics; Carbon stabilization. ABSTRACT Soil degradation processes due to intensified agriculture may be counteracted by an extended knowledge on soil humus dynamics at molecular level. Here we show that the molecular composition of the soil Humeome changes substantially after 1 and 3 years of conventional tillage under maize cropping. Application of Humeomics sequential chemical fractionation not only separated from soil more than twice the organic carbon extracted by traditional methods, but also enabled to identify ten times more molecular structures using GC-MS and high-resolution ESI-Orbitrap-MS. The fine molecular description of the soil Humeome revealed a decrease of soil organic matter (SOM) hydrophobic protection with prolonged tillage and a potential loss of small nitrogen-rich compounds. We showed for the first time an abundance of heterocyclic nitrogen compounds which are persistent in SOM due to a