Subsurface drip fertigation optimizes nitrogen distribution in soil under maize cultivation

Background and Aims: Precise nitrogen (N) supply is vital to sustainable maize production amid food security challenges. This study aimed to evaluate subsurface drip fertigation (SSDF) for optimizing nitrogen distribution and enhancing maize productivity while reducing environmental risks. Methods The study was conducted at ICAR-IARI, New Delhi (2022–2023), using a split-plot design. SSDF was tested with 0–100% recommended dose of N (RDN) applied in 3–4 splits, combined with greengram residue incorporation. Soil mineral N (NH₄⁺-N, NO₃⁻-N) was measured at 0–50 cm depths and 0–20 cm from emitters, along with urease activity and grain yield. Results SSDF outperformed conventional methods, achieving peak NH₄⁺-N at 52.7 mg kg⁻¹ and NO₃⁻-N at 36.3 mg kg⁻¹ in the 20–30 cm layer under 100% RDN-4S treatment. Four splits-maintained N supply better than three splits. Residue incorporation improved soil N by 10–13% and urease activity by 11–13% (13.9 µg g⁻¹ h⁻¹). Yields from 75% RDN-4S (6.6 t ha⁻¹) equaled 100% RDN-4S (6.7 t ha⁻¹), achieving 25% N savings with significant N-yield correlations (r = 0.8–0.85). Conclusion SSDF optimized nitrogen distribution by concentrating mineral N in the 20–30 cm root zone and enabled 25% reduction in N application (75% RDN-4S) while maintaining equivalent maize yields. The integration of four-split applications with residue incorporation enhanced soil N availability and microbial activity, demonstrating SSDF's potential for sustainable maize production.