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Soil temperature, nitrogen concentration, and residence time affect nitrogen uptake efficiency in citrus
J M S Scholberg1, L R Parsons, T A Wheaton
1Agronomy Dep., Univ. of Florida, Gainesville 32611, USA. jmscholberg@mail.ifas.ufl.edu
Journal of Environmental Quality
|May 25, 2002
Summary
Optimizing nitrogen uptake efficiency (NUE) in citrus requires careful management of irrigation. Longer residence times and controlled nitrogen application rates enhance NUE, crucial for sustainable agriculture.
Area of Science:
- Agricultural Science
- Environmental Science
- Soil Science
Background:
- Nitrogen (N) is vital for citrus growth, but efficient uptake is challenged by environmental and soil factors.
- Reclaimed water, often used for irrigation, presents variable nitrogen concentrations and application volumes.
- Understanding nitrogen uptake efficiency (NUE) is critical for sustainable citrus irrigation and minimizing environmental impact.
Purpose of the Study:
- To elucidate the environmental and soil factors controlling nitrogen uptake efficiency in citrus.
- To determine the effects of residence time and nitrogen concentration on NUE in young citrus seedlings.
- To develop a predictive model for nitrogen uptake and assess irrigation impacts on mature citrus trees.
Main Methods:
- Studied the impact of varying residence times (2-8 hours) and nitrogen concentrations (low vs. high frequency applications) on citrus seedling NUE.
- Developed a predictive model for nitrogen uptake incorporating root density, nitrogen concentration, and soil temperature (Ts).
- Calculated nitrogen uptake temperature sum (UTS) and minimum uptake periods required to prevent nitrogen leaching.
Main Results:
- Increased residence times from 2 to 8 hours significantly enhanced NUE in citrus seedlings.
- A predictive model demonstrated that longer uptake periods (5-16 degrees CdN) are needed at lower initial soil nitrogen concentrations.
- Higher reclaimed water application rates (2500 mm yr(-1)) drastically reduced NUE (summer: 63%, winter: 28%) compared to lower rates (400 mm yr(-1)).
Conclusions:
- Residence time and nitrogen application strategy are key factors influencing nitrogen uptake efficiency in citrus.
- Optimized irrigation practices, considering water volume and nitrogen concentration, are essential for maximizing nitrogen use efficiency from reclaimed water.
- High irrigation volumes can lead to nitrogen loss below the root zone, reducing uptake efficiency, particularly in winter months.