Subsurface fertilization geometry synergies enhanced grain yield, nitrogen use efficiency and reduced greenhouse gas emissions: A global meta-analysis

Abstract

Context

Subsurface fertilizer application (SFA) is an extremely valuable strategy to enhance crop productivity and reduce environmental impacts. However, the effects of SFA geometry—particularly depth and lateral distance—on agronomic yields, nitrogen use efficiency (NUE), and greenhouse gas (GHG) emissions remain poorly understood.

Objective

This study aimed to quantify the effects of subsurface fertilizer application geometry (depth and lateral distance) on crop yield, nitrogen use efficiency, and greenhouse gas emissions through a global meta-analysis of 256 studies covering grain crops (rice, maize, wheat).

Methods

We conducted a global meta-analysis integrating 2109 observations to evaluate the impact of SFA depth, lateral distance, and nitrogen inputs on yield, NUE, and GHG emissions in rice, maize, and wheat.

Results

Our results demonstrate that SFA significantly increased yield by 16.1 % (rice), 21.0 % (maize), and 7.2 % (wheat), improved NUE by 26.9 % (rice), 10.8 % (maize), and 11.1 % (wheat), and reduced GHG emissions by 102.9 % (rice), 34.8 % (maize), and 21.2 % (wheat) compared to broadcast fertilization (BFA). Optimal SFA geometry varied by crop: depths of ≤ 5 cm and 10–15 cm for maize, and 10–15 cm for rice and wheat, and lateral distances of 0–10 cm for rice and 10–20 cm for maize were critical for maximizing productivity and NUE. Environmental factors, including mean annual precipitation (MAP > 800 mm) and temperature (MAT > 15°C), as well as soil properties such as soil organic matter (SOM) and total nitrogen (TN) content, further enhanced the benefits of SFA. Importantly, SFA exhibited a synergistic effect, simultaneously increasing yield, improving NUE, and reducing GHG emissions, highlighting its potential as a sustainable fertilization strategy.

Conclusion

These findings provide actionable insights for optimizing SFA practices to enhance agricultural sustainability under diverse crop and environmental conditions.