The effect of temperature on the decomposition of different parts of maize residues in a solonchak

Abstract Returning maize residue not only helps maintain soil fertility but also local soil carbon balance. Although there have studies of maize residue decomposition, seldom focused on combining different parts of maize residue under field and incubation experiments at different temperatures in saline and alkaline soils. We carried out an incubated decomposition experiment of maize residue (15, 25, 35℃) and a field experiment (12 ~ 29℃) by litter bag method within 90 days in a Solonchak. A double exponential model was used to simulate labile C (carbon) and recalcitrant C in decomposition. The correlation showed a closed decomposition relationship (R2 > 0.98) for double exponential model. Field and laboratory experiments showed decomposition increased with temperature and followed order leaf (35%~73%) > stem (35%~72%) > root (21%~63%). The decomposition increased rapidly within first 15 days and then slowed. The decomposition rates (day−1) of maize residue were 0.10 ~ 0.16 (labile C) and 0.0005 ~ 0.0015 (recalcitrant C) at field, and 0.05 ~ 0.10 and 0.0001 ~ 0.0014 at lab. The decomposition rate (day−1) of native soil organic C (SOC) labile C (0.05 ~ 0.13) and recalcitrant C (0.0002 ~ 0.0005) changed with temperature, but recalcitrant C changed not (0.98). The decomposition rate of recalcitrant C increased by 180%~1100%, which was higher than that of labile C (50%~80%) with increasing temperature. The Q10 value showed decomposition of maize residue and SOC at 15 ~ 25 °C was larger than that at 25 ~ 35 °C. By adding 1 g maize stem or leaf to field, 0.15 ~ 0.39 g or 0.18 ~ 0.33 g C stored in soil, respectively. In summary, increased temperature significantly accelerated maize residue decomposition by increasing decomposition rate and turning a part of recalcitrant C into labile C. The temperature sensitivity of maize residue and SOC decomposition was higher at 15 ~ 25 °C than at 25 ~ 35 °C. The simulated saline and alkaline soil C stock was 0.1 ~ 1.7 kg ha−1 yr−1 from maize stem and leaf return facing warming.