Optimizing irrigation and nitrogen for wheat through empirical modeling under semi-arid environment

Area of Science:

• Agricultural Science
• Agronomy
• Environmental Science

Background:

• Water scarcity in Pakistan necessitates efficient irrigation practices, with per capita availability below 1000 m³.
• Excessive or insufficient nitrogen fertilizer negatively impacts wheat yield and the environment.
• Optimizing water and nitrogen is key to enhancing water productivity and economic returns in grain yield.

Purpose of the Study:

• To optimize the volume of water per irrigation and nitrogen application for wheat cultivation.
• To develop empirical regression models for predicting optimal irrigation and nitrogen levels.
• To improve water productivity and economic returns through efficient resource management.

Main Methods:

• A split-plot design experiment with three replications was conducted over two growing seasons (2012-2014).
• Four irrigation levels (120-300 mm) and four nitrogen levels (60-240 kg ha⁻¹) were applied.
• Empirical regression models based on quadratic equations and economic analysis were developed using grain yield data.

Main Results:

• Economic optimum nitrogen levels varied from 107 to 164 kg ha⁻¹ (2012-2013) and 117 to 165 kg ha⁻¹ (2013-2014) across irrigation levels.
• Optimal irrigation water was predicted at 253 mm (2012-2013) and 256 mm (2013-2014).
• Reducing irrigation from 300 mm to 240 mm did not significantly reduce crop yield (P < 0.01).
• Excessive nitrogen application ranged from 31.2% to 55.4% at higher nitrogen rates.

Conclusions:

• The relationship between irrigation and nitrogen can be leveraged for efficient management, reducing losses.
• Empirical equations developed can guide farmers in semi-arid regions to determine optimal irrigation and nitrogen levels for maximum economic return.
• Sustainable wheat production requires integrated water and nitrogen management strategies.