Responses of soil hydrolytic enzymes, ammonia-oxidizing bacteria and archaea to nitrogen applications in a temperate grassland in Inner Mongolia.
We used a seven-year urea gradient applied field experiment to investigate the effects of nitrogen (N) applications on soil N hydrolytic enzyme activity and ammonia-oxidizing microbial abundance in a typical steppe ecosystem in Inner Mongolia. The results showed that N additions inhibited the soil N-related hydrolytic enzyme activities, especially in 392 kg N ha(-1 )yr(-1) treatment. As N additions increased, the amoA gene copy ratios of ammonia-oxidizing archaea (AOA) to ammonia-oxidizing bacteria (AOB) decreased from 1.13 to 0.65. Pearson correlation analysis showed that the AOA gene copies were negatively related with NH4(+)-N content. However, the AOB gene copies were positively correlated with NO3(-)-N content. Moderate N application rates (56-224 kg N ha(-1 )yr(-1)) accompanied by P additions are beneficial to maintaining the abundance of AOB, as opposed to the inhibition of highest N application rate (392 kg N ha(-1 )yr(-1)) on the abundance of AOB. This study suggests that the abundance of AOB and AOA would not decrease unless N applications exceed 224 kg N ha(-1 )yr(-1) in temperate grasslands in Inner Mongolia.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Xinyu
X
Zhang
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Yuqian
Y
Tang
School of Geographic Sciences, Northeast Normal University, Changchun 130024, China.
Yao
Y
Shi
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Nianpeng
N
He
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Xuefa
X
Wen
State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
Qiang
Q
Yu
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Chunyu
C
Zheng
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Xiaomin
X
Sun
The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, New Zealand.
Weiwen
W
Qiu
D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D002681:China; D017753:Ecosystem; D005308:Fertilizers / Q000382:microbiology; D065948:Grassland; D006868:Hydrolysis; D058465:Nitrification / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D012987:Soil; D012988:Soil Microbiology
D005308:Fertilizers; D012987:Soil; D000641:Ammonia; D009584:Nitrogen