Soil nitrate accumulation, leaching and crop nitrogen use as influenced by fertilization and irrigation in an intensive wheat–maize double cropping system in the North China Plain |
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Authors: | Quanxiao Fang Qiang Yu Enli Wang Yuhai Chen Guoliang Zhang Jing Wang Longhui Li |
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Institution: | (1) Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, A11 Datun Road Anwai, Beijing, 100101, China;(2) Graduate School of the Chinese Academy of Sciences, Beijing, 100039, P.R. China;(3) CSIRO Land and Water, GPO Box 1666, Canberra, ACT, 2601, Australia;(4) Agronomy College, Shandong Agricultural University, Taian, 271018, Shandong, P.R. China |
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Abstract: | There is a growing concern about excessive nitrogen (N) and water use in agricultural systems in North China due to the reduced
resource use efficiency and increased groundwater pollution. A two-year experiment with two soil moisture by four N treatments
was conducted to investigate the effects of N application rates and soil moisture on soil N dynamics, crop yield, N uptake
and use efficiency in an intensive wheat–maize double cropping system (wheat–maize rotation) in the North China Plain. Under
the experimental conditions, crop yield of both wheat and maize did␣not␣increase significantly at N rates above 200 kg N ha−1. Nitrogen application rates affected little on ammonium-N (NH4-N) content in the 0–100 cm soil profiles. Excess nitrate-N (NO3-N), ranging from 221 kg N ha−1 to 620 kg N ha−1, accumulated in the 0–100 cm soil profile at the end of second rotation in the treatments with N rates of 200 kg N ha−1 and 300 kg N ha−1. In general, maize crop has higher N use efficiency than wheat crop. Higher NO3-N leaching occurred in maize season than in wheat season due to more water leakage caused by the concentrated summer rainfall.
The results of this study indicate that the optimum N rate may be much lower than that used in many areas in the North China
Plain given the high level of N already in the soil, and there is great potential for reducing N inputs to increase N use
efficiency and to mitigate N leaching into the groundwater. Avoiding excess water leakage through controlled irrigation and
matching N application to crop N demand is the key to reduce NO3-N leaching and maintain crop yield. Such management requires knowledge of crop water and N demand and soil N dynamics as
they change with variable climate temporally and spatially. Simulation modeling can capture those interactions and is considered
as a powerful tool to assist in␣the␣future optimization of N and irrigation managements.
Section Editor: L. Wade |
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Keywords: | Nitrate-N accumulation and leaching Wheat– maize double cropping system Crop nitrogen use Ground water North China Plain |
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