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

Springer Netherlands
Publication Type:
Journal Article
Plant and Soil, 2006, 284 (1-2), pp. 335 - 350
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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 wheatmaize double cropping system (wheatmaize 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 0100 cm soil profiles. Excess nitrate-N (NO3-N), ranging from 221 kg N ha-1 to 620 kg N ha-1, accumulated in the 0100 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.
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