Sub-surface drip-fertigation and legume residue improved maize yield and nitrogen use

Maize (Zea mays L.), a multi-utility cereal crop, has a high requirement for nitrogen (N). However, conventional N application methods fail to achieve potential yield and contribute to environmental pollution. Thus, a 2-year (2022 and 2023) field investigation was conducted to understand the effect of sub-surface drip-fertigation (SSDF) and legume residue incorporation (3 t ha-1) on improving maize yield, uptake, remobilization, and use-efficiency of N. Four N levels, viz., 0, 50, 75, and 100% recommended dose of N (RDN) applied in 3-splits (3S) and 4-splits (4S), were compared with conventional maize cultivation, fertilized with 150 kg N ha-1 (CMC-N150). Variable N fertigation with SSDF significantly affected the dry matter (DM) and N remobilization from leaves towards kernel; at lower doses of N maize tended to mobilize higher DM and N towards kernel. Better growth, higher nutrient uptake, and better remobilization efficiency of DM/N led to higher grain yield under 75% RDN (19-23% increase) and 100% RDN (20-25% increase) sub-surface drip-fertigated, compared to CMC-N150. Using 50% RDN through SSDF yielded grain on par with CMC-N150, thus saving 50% N. Moreover, applying N in 4-splits (4S) gave 3-5% yield advantage over 3-splits. Partial factor productivity of N (PFPN) and agronomic N-use efficiency (AEN) of different SSDF treatments increased by 18-100% and 40-99%, respectively over CMC-N150. Greengram residue incorporation improved maize yield by 5-8%, PFPN by 4-5% over no-residue incorporation. Overall, there was a 25-50% N economy with concomitant yield improvement under SSDF over conventional N management. The SSDF coupled with legume residue incorporation could be a promising technology for enhancing N-use efficiency globally; however, it needs policy support for adoption in the producer's field.