Estimating total nitrogen deposition in agroecosystems in northern China during the wheat cropping s

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Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an in-tensive agricultural and industrial region with large emissions of NHx and NOy To quantify N deposition, total airborne N deposition was determined at three agricultural sites using a manual integrated total ni-trogen input (ITNI) system during growth of winter wheat (Triticum aestivum L.) and Italian ryegrass (Lolium multiflorum Lam.) from September 2005 to May 2006. Total estimated N deposition averaged 54.9 and 43.2 kg N/hm2 across the three sites when wheat was grown to flowering and maturing, respectively. The aver-age value was 50.2 kg N/hm2 when ryegrass was the indicator plant. Both indicator species gave similar total airborne N input results. The intermediate level of N supplied resulted in the highest N deposition, and the ratio of N acquired from deposition to total N content of the whole system decreased with increasing N supply to the roots. The contribution of atmospheric N to the total N content of the wheat and ryegrass sand culture systems ranged from 10% to 24%.
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