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Losses in Carbon and Nitrogen Stocks in Soil Particle‐Size Fractions along Cultivation Chronosequences in Inner Mongolian Grasslands
Author(s) -
He Nianpeng,
Zhang Yunhai,
Dai Jingzhong,
Han Xingguo,
Yu Guirui
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0258
Subject(s) - silt , soil carbon , grassland , nitrogen , agronomy , carbon stock , environmental science , total organic carbon , soil organic matter , soil science , chemistry , zoology , soil water , environmental chemistry , ecology , geology , biology , climate change , paleontology , organic chemistry
Cultivation in semiarid grasslands induces large changes in soil organic matter (SOM) stock. To better predict the effects of cultivation on SOM pools, there is a need to identify the soil fractions that are affected and the extent to which they are affected. Using four cultivation chronosequences in Inner Mongolian grasslands of northern China, we investigated the changes in soil organic carbon (SOC) and total nitrogen (N) stocks in soil particle‐size fractions to identify the effect of cultivation on SOM dynamics. The results showed that conversion of native grasslands into croplands significantly decreased the SOC stocks (4.34–31.65 Mg C ha −1 ) and N (0.19–2.54 Mg N ha −1 ) in the 0‐ to 100‐cm layer after cultivation. Prominent changes were observed in the SOC and N stocks in the 0‐ to 10‐cm layer and were, on average, 6.56 Mg C ha −1 (24.85%) and 0.63 Mg N ha −1 (23.48%), respectively. The effect of cultivation on the SOC and N stocks in soil fractions was in the order sand > silt > clay. The C and N stocks in the 0‐ to 10‐cm soil layer in the sand fraction in croplands decreased, on average, by 4.74 Mg C ha −1 (35.86%) and 0.48 Mg N ha −1 (41.30%), respectively, compared with those in native grasslands. The declines in the silt and clay fractions were small. Thus, sand fraction was a more important contributor to C and N losses in soil after cultivation than silt or clay fraction. Our findings indicate that the preliminary responses of SOC and N to cultivation in a semiarid grassland area and have significant implications for assessing the loss or gain of C and N during grassland conversion.