291-5 Soil Nitrogen Fluxes in Wheat-Corn Double Cropping Systems in the North China Plain.

See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Nitrogen-Use Efficiency, Nitrogen Leaching, and Nitrous Oxide Emissions As Influenced by Management Practices: I
Tuesday, October 23, 2012: 9:05 AM
Duke Energy Convention Center, Room 202, Level 2
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Chunsheng Hu1, Wen-Xu Dong2, Yu-Ming Zhang2, Xiao-Xin Li2 and Shu-Ping Qi1, (1)Center for Agricultural Resorces Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, China
(2)Institute of Genetics and Developmental Biology, Center for Agricultural Resources Research, Shijiazhuang, China
The North China Plain (NCP) is one of the areas of intensive cereal (wheat and maize) production in China. A critical challenge facing the agro-production sector of the NCP, however, is over-application of chemical fertilizers. This study investigated relationship between nitrogen (N) fluxes and crop nutrient uptake/loss processes at conventional fertilization rate of 400 kg-N/ha in the winter wheat/summer maize crop rotation system in the piedmont region of NCP. The results showed that a total N input of 561~580 kg/ha and output of 468~494 kg/ha resulted in a N surplus of 86~93 kg/ha per year in the soil. Organic N load of the above amount in the study area was 24~36 kg/ha. N loss via ammonia volatilization and NO3--N leaching was 60 kg/ha and 47~84 kg/ha per year, respectively, collectively accounting for 30% of applied N fertilizer in the region. N loss via nitrification-denitrification was only 5.0~8.7 kg/ha per year, accounting for 1%~2% of applied N fertilizer. Ammonia volatilization and NO3--N leaching were the main modes of N loss, and therefore the main drivers of lower N fertilizer utilization rate in the study area. Appropriate management practices such as adjustments of the rates and time of N fertilization and irrigation were important for decreasing ammonia volatilization, nitrate-N accumulation in deep soil profile and therefore the mitigation of nitrate N loss in the region. Amendments with wheat/corn straw changed the rates of N transformation and migration in the soil, which also resulted in low NH3--N loss and nitrate leaching. Analysis of precision fertilization via NO3--N or hyper-spectra information also showed that the main indices of N loss were the amount of soil available nutrient and crop nutrient content. Control-release fertilization and precision fertilization techniques improved crop nutrient uptake, which in turn increased N use efficiency.
See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Nitrogen-Use Efficiency, Nitrogen Leaching, and Nitrous Oxide Emissions As Influenced by Management Practices: I