Chong Chen Yuji Jiang Bo Sun Hu Zhou Paul D. Hallett
Manure and lime as fertiliser and conditioner are widely used on red soils to improve soil fertility and to alleviate soil acidity. Investigating the effects of these compounds on soil interfacial properties is very important for understanding some physical, chemical, and biological processes that are often overlooked. Using a long-term field experiment (2002–2018) on a red loamy clay soil, we explored how the soil water vapour sorption isotherm, soil organic carbon (SOC), pH, cation exchange capacity (CEC), specific surface area (SSA), and water repellency (WR) interacted and were affected by low-rate pig manure (LM, 150 kg N ha−1 year−1), high-rate pig manure (HM, 600 kg N ha−1 year−1), and high-rate pig manure with lime (HML). The HML only increased soil pH relative to the HM. The SSA determined with N2 (SSAN2) showed a significant negative correlation with SOC. Both SSA determined with H2O (SSAH2O) and contact angle (CA) were significantly positively correlated with SOC. Manure amendments increased soil water content change (WCC) in the water activity (aw) range of 0.05–0.2 (WCC0.05–0.2) by 6.3–30.2%, but decreased WCC0.2–0.6 and WCC0.6–0.93 by 5.1–12.5% and 2.8–7.0%, respectively. Local hysteresis became more pronounced with high manure or high manure with lime amendment in the intermediate aw range (0.45–0.75). The observed changes of water vapour sorption were attributed to the alteration of SOC affecting SSA and WR.
Scontact angle, hysteresis, soil organic carbon, specific surface area, water vapour sorption