Modeling nitrogen uptake and potential nitrate leaching under different irrigation programs in nitrogen-fertilized...

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Excessive nitrogen (N) fertilizer and irrigation can lead to environmental hazards like groundwater contamination.
• Nitrate-nitrogen (NO3-N) leaching below the root zone poses a risk to water quality.
• The Nitrate Leaching and Economic Analysis Package (NLEAP) is a model for estimating NO3-N leaching.

Purpose of the Study:

• To evaluate the NLEAP model's accuracy in simulating crop N uptake and NO3-N leaching under varied irrigation regimes.
• To assess the model's utility for site-specific N management in tomato cultivation.

Main Methods:

• Field experiment using large lysimeters with tomato crops (H-2274 variety).
• Application of nitrogen fertilizer at 140 kg N ha(-1) split between ammonium sulphate and ammonium nitrate.
• Irrigation treatments based on Class A-Pan evaporation coefficients (C 0.75, 1.00, 1.25, 1.50).
• Estimation of parameters like leaching index (LI), annual leaching risk potential (ALRP), N available for leaching (NAL), N leached (NL), and N uptake (NU) using NLEAP.

Main Results:

• NLEAP model showed significant correlations with measured crop N consumption (R2 = 0.92, P < 0.03 first year; R2 = 0.86, P < 0.06 second year).
• The model accurately predicted nitrate-nitrogen leaching (NL) with high correlations (R2 = 0.96, P < 0.01 first year; R2 = 0.97, P < 0.01 second year).
• NLEAP effectively simulated N uptake and NL under varying irrigation programs.

Conclusions:

• The NLEAP model is a valuable tool for estimating nitrate-nitrogen movement below the root zone in agricultural settings.
• NLEAP-derived parameters can inform improved nitrogen management practices and fertilizer recommendations.
• Utilizing NLEAP can mitigate the adverse effects of nitrogen fertilizer on groundwater quality and improve farm economic viability.