Agriculture Reference
In-Depth Information
8 Managing Soil Organic
Carbon Concentration
by Cropping Systems
and Fertilizers in the
North China Plain
Jin Qing, Xiangbin Kong, and Rattan Lal
CONTENTS
8.1 Introduction .................................................................................................. 189
8.2 Data and Methods ......................................................................................... 190
8.2.1 Study Area ........................................................................................ 190
8.2.2 Data Collection ................................................................................. 191
8.2.3 Data Analysis .................................................................................... 193
8.3 Results and Discussions ................................................................................ 193
8.3.1 Change in SOC Concentration from 1980 to 1999 ........................... 193
8.3.2 Change in SOC Concentration from 1999 to 2006 .......................... 195
8.3.3 Change in SOC Concentration as a Result of Changes in the
Cropping System ............................................................................... 195
8.3.4 Results of Changes in the Cropping System and the Increased
Use of Fertilizer over Time ............................................................... 197
8.4 Conclusions ................................................................................................... 198
Acknowledgments .................................................................................................. 199
Abbreviations ......................................................................................................... 199
References .............................................................................................................. 199
8.1 INTRODUCTION
Concentration of soil organic carbon (SOC) under different cropping systems
depends mainly on the types of tillage and residue management practices. Haas et
al. (1957) reported an average decrease of 42% in the SOC concentration in the
15-cm depth after 30 to 40 years of dry land management at experiment stations in
the Great Plains of the United States. Jenny (1933) proposed that SOC concentration
would reach a new equilibrium level after 50 years of cultivation. Other studies have
reported similar levels of decline in the concentration of SOC in the surface layer as
189
 
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