Effects of crop types and nitrogen fertilization on temperature sensitivity of soil respiration in the semi-arid Loess Plateau

摘要

Temperature sensitivity of soil respiration (Qio) is an important mechanism for the possible feedback between global carbon cycle and climate system. Knowledge of how crop types and nitrogen (N) fertilization affect Qio is critical for estimating soil respiration and carbon cycling in agro-ecosystem. A two-year field experiment was conducted with cold-resistant (winter wheat; Triticum aestivum L) and thermophilic (spring maize; Zea mays L.) crops at two N fertilization levels (no fertilization (CK) and 160 kgN hm(-1)) from October 2013 to September 2015 in semi-arid Loess Plateau. Annual mean soil respiration and Qio in maize were 20% (1.85 vs. 1.54 mu mol m(-2) s(-1)) and 36% (2.49 vs.1.83) higher than that in wheat. Nitrogen fertilization resulted in a 35% increase in annual mean soil respiration (1.95 vs. 1.44 mu mol m(-2) s(-1)) and a 11% decrease in Qio (2.05 vs. 2.28) compared with the CK treatment. Soil respiration was positively related to root biomass, whereas no significant relationship was found between root biomass and Qio. Therefore, it can be concluded that soil respiration and temperature sensitivity of soil respiration are significantly influenced by crop types and N fertilization regimes, which should be considered in calculating carbon budget in agro-ecosystem using carbon models. (C) 2016 Elsevier B.V. All rights reserved.