Long-term stabilization of crop residues and soil organic carbon affected by residue quality and initial soil pH

Abstract

Residues differing in quality and carbon (C) chemistry are presumed to contribute differently to soil pH change and long-term soil organic carbon (SOC) pools. This study examined the liming effect of different crop residues (canola, chickpea and wheat) down the soil profile (0–30 cm) in two sandy soils differing in initial pH as well as the long-term stability of SOC at the amended layer (0–10 cm) using mid-infrared (MIR) and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. A field column experiment was conducted for 48 months. Chickpea- and canola-residue amendments increased soil pH at 0–10 cm in the Podzol by up to 0.47 and 0.36 units, and in the Cambisol by 0.31 and 0.18 un..