title: The impact of exogenous N supply on soluble organic nitrogen dynamics and nitrogen balance in a greenhouse vegetable system.
abstract: A long-term greenhouse experiment (2004-2012) was conducted with continuous tomato (Lycopersicum esculentum Mill.) plantings to understand the influence of an exogenous nitrogen supply from irrigation water, chemical fertilizer, or organic amendment on the N balance and soluble organic nitrogen (SON). The results from 16 tomato growing seasons indicated that the application of organic amendment (manure and straw) alone (Or-N) resulted in the same yield as the conventional chemical N with organic amendment (Co-N) and the reduced chemical N with organic amendment (Re-N) treatments. The annual apparent N loss was >1000 and 438 kg N ha(-1) in the Co-N and Re-N treatments, respectively. Over the study period, the SON in the 1.8 m soil profile was 1449 and 1978 kg N ha(-1) in the Re-N and Co-N treatments, respectively, it was 1.7- and 2.3-fold higher than that observed in the Or-N treatment, which indicated that SON increased with the chemical N application. The percentage of SON in the cumulative soluble N (SON plus mineral N) ranged from 28% to 44%, and there were no significant differences across the 0-0.6, 0.6-1.2, and 1.2-1.8 m soil profile, which indicated that the leaching and distribution of SON was similar to those of the mineral N in the 0-1.8 m soil profile. We conclude that the mobility of soluble organic N in the 0-1.8 m of the soil was synchronous with the mineral N under a greenhouse production system, and the risk of soluble organic N leaching increased with inorganic N application rate. Therefore, leaching of SON in the intensive agriculture should not be ignored when evaluating the risk of N leaching.
authors.affiliation: College of Resources and Environmental Sciences, Qingdao Agriculture University, Qingdao 266109, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Kang
authors.affiliation: College of Resources & Environment, Huazhong Agriculture University, Wuhan 430070, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Ren
authors.affiliation: College of Resources and Environmental Sciences, Qingdao Agriculture University, Qingdao 266109, China.
authors.forename: Li
authors.initials: L
authors.lastname: Junliang
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. Electronic address: qchen@cau.edu.cn.
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Jingguo
authors.initials: J
authors.lastname: Wang
mesh_terms: D000383:Agriculture / Q000379:methods*; D004784:Environmental Monitoring; D005308:Fertilizers / Q000032:analysis*; D006801:Humans; D009584:Nitrogen / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D014675:Vegetables
chemical_list: D005308:Fertilizers; D012989:Soil Pollutants; D009584:Nitrogen
keywords: Irrigation water; Manure; Mineral N; N fertilizer; Plastic greenhouse