Normalized difference vegetation index sensor-based nitrogen management in bread wheat (Triticum aestivum L.):...

Area of Science:

• Agricultural Science
• Agronomy
• Soil Science

Background:

• Optimizing nitrogen (N) fertilizer application is crucial for maximizing crop yields and minimizing environmental impact.
• Traditional N management strategies often involve fixed application rates, which may not be optimal for varying field conditions.
• Sensor-based technologies offer potential for precision agriculture, enabling dynamic adjustments to nutrient application.

Purpose of the Study:

• To evaluate the impact of fixed versus variable nitrogen (N) doses, guided by a normalized difference vegetation index (NDVI) sensor, on wheat.
• To assess the effects on wheat yield, nutrient uptake, nitrogen use efficiency (NUE), and soil nitrogen balance.
• To determine the optimal N management strategy for wheat cultivation in the eastern sub-Himalayan plains.

Main Methods:

• Field experiment with 10 treatments involving fixed and variable N doses under a randomized complete block design.
• Variable doses were determined using NDVI sensor readings after initial N applications.
• Included fixed N rates (120, 150 kg N ha⁻¹), sensor-guided variable rates, a nitrogen-rich control (225 kg N ha⁻¹), and an absolute control (no N).

Main Results:

• A basal N dose of 60 kg N ha⁻¹ followed by 60 kg N ha⁻¹ at crown root initiation, plus sensor-guided N, significantly boosted wheat grain yield and N uptake.
• Straw N uptake was highest in the N-rich control (225 kg N ha⁻¹).
• Partial factor productivity and NUE declined with increasing N rates; apparent N recovery was similar between sensor-guided and lower N dose treatments.
• Soil N status decreased in most treatments, except the N-rich strip, indicating potential for N loss.
• Partial N balance was negative for all treatments except the control.

Conclusions:

• Sensor-guided nitrogen application, particularly with an initial basal and crown root initiation dose, is effective for optimizing wheat yields and nutrient uptake.
• The normalized difference vegetation index (NDVI) sensor is a valuable tool for rational fertilizer N management in wheat.
• This approach is particularly relevant for wheat grown in the eastern sub-Himalayan plains, promoting efficient N use and potentially reducing environmental losses.