Effects of nitrogen fertilization on soil respiration in temperate grassland in Inner Mongolia,China |
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Authors: | Qin Peng Yunshe Dong Yuchun Qi Shengsheng Xiao Yating He Tao Ma |
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Institution: | (1) Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China;(2) Graduate School of the Chinese Academy of Sciences, Beijing, 100049, China;(3) College of Resource and Environment Science, Northwestern Agricultural and Forestry University, Yangling, 712100, China; |
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Abstract: | Nitrogen addition to soil can play a vital role in influencing the losses of soil carbon by respiration in N-deficient terrestrial
ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN, 200 kg N ha−1 year−1; MN, 100 kg N ha−1 year−1; LN, 50 kg N ha−1 year−1) on soil respiration compared with non-fertilization (CK, 0 kg N ha−1 year−1), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Results showed that N fertilization
did not change the seasonal patterns of soil respiration, which were mainly controlled by soil heat-water conditions. However,
N fertilization could change the relationships between soil respiration and soil temperature, and water regimes. Soil respiration
dependence on soil moisture was increased by N fertilization, and the soil temperature sensitivity was similar in the treatments
of HN, LN, and CK treatments (Q
10 varied within 1.70–1.74) but was slightly reduced in MN treatment (Q
10 = 1.63). N fertilization increased soil CO2 emission in the order MN > HN > LN compared with the CK treatment. The positive effects reached a significant level for HN
and MN (P < 0.05) and reached a marginally significant level for LN (P = 0.059 < 0.1) based on the cumulative soil respiration during the 2007 growing season after fertilization (July–September
2007). Furthermore, the differences between the three fertilization treatments and CK reached the very significant level of
0.01 on the basis of the data during the first entire year after fertilization (July 2007–June 2008). The annual total soil
respiration was 53, 57, and 24% higher than in the CK plots (465 g m−2 year−1). However, the positive effects did not reach the significant level for any treatment in the 2008 growing season after the
second year fertilization (July–September 2008, P > 0.05). The pairwise differences between the three N-level treatments were not significant in either year (P > 0.05). |
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