title: Improving water management practices to reduce nutrient export from rice paddy fields.
abstract: Nitrogen (N) and phosphorus (P) loss from rice paddy fields represents a significant threat to water quality in China. In this project, three irrigation-drainage regimes were compared, including one conventional irrigation-drainage regime, i.e. continuous submergence regime (CSR), and two improved regimes, i.e. the alternating submergence-nonsubmergence regime (ASNR) and the zero-drainage irrigation technology (ZDIT), to seek cost-effective practices for reducing nutrient loss. The data from these comparisons showed that, excluding the nutrient input from irrigation, the net exports of total N and total P via surface field drainage ranged from -3.93 to 2.39 kg ha and 0.17 to 0.95 g ha(-1) under the CSR operation, respectively, while N loss was -2.46 to -2.23 kg ha(-1) and P export was -0.65 to 0.31 kg ha(-1) under the improved regimes. The intensity of P export was positively correlated to the rate of P application. Reducing the draining frequency or postponing the draining operation would shift the ecological role of the paddy field from a nutrient export source to an interception sink when ASNR or the zero-drainage water management was used. In addition, since the rice yields are being guaranteed at no additional cost, the improved irrigation-drainage operations would have economic as well as environmental benefits.
authors.affiliation: The Research Centre of Eco-environmental Science, Zhejiang University, 268th KuanXian Avenue, Hangzhou 310029, China. zjy@zju.edu.cn
authors.forename: Zhi-Jian
authors.initials: ZJ
authors.lastname: Zhang
authors.forename: Ju-Xiang
authors.initials: JX
authors.lastname: Yao
authors.forename: Zhao-De
authors.initials: ZD
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Xian-Yong
authors.initials: XY
authors.lastname: Lin
authors.forename: George F
authors.initials: GF
authors.lastname: Czapar
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Zhang
mesh_terms: D057914:Agricultural Irrigation / Q000379:methods* / Q000592:standards; D000704:Analysis of Variance; D002681:China; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring / Q000379:methods*; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis; D012275:Oryza; D010758:Phosphorus / Q000032:analysis; D011891:Rain; D036226:Seedlings; D014867:Water / Q000737:chemistry; D014872:Water Movements
chemical_list: D014867:Water; D010758:Phosphorus; D009584:Nitrogen