Response of subsoil organic matter contents and physical properties to long‐term, high‐rate farmyard manure application

Application of farmyard manure (FYM) is common practice to improve physical and chemical properties arable soil crop yields. However, studies on effects FYM application mainly focussed topsoils, whereas subsoils have rarely been addressed so far. We, therefore, investigated the 36-year with different rates annual organic carbon (OC) addition (0, 469, 938 1875 g C m−2 a−1) OC contents a Chernozem in 0–30 cm (topsoil) 35–45 (subsoil) depth. We also its structure hydraulic subsoil. X-ray computed tomography was used analyse response subsoil macropore system (≥19 μm) distribution particulate matter (POM) applications, which were related total (TOC) water-extractable (WEOC). show that FYM-C 469 a−1 caused increases TOC WEOC only topsoil, ≥938 necessary for enrichment At this depth, subdivision into sources shows most increase due fresh POM, likely by stimulation root growth bioturbation. The went along macroporosity connectivity. neither observed plant-available water capacity nor unsaturated conductivity. In conclusion, very high over long periods can content at our study site, but largely based fresh, easily degradable POM accompanied losses when considering discrepancy between rate soil. Highlights A new image processing procedure distinguish decomposed POM. stock large extend labile Potential long-term storage limited. has no effect