Influence of Sub-surface Drip Irrigation on Nitrogen Dynamics and Partitioning in Different Plant Parts under Conservation Agriculture-based Cereal Systems

Abstract

Intensive cereal-based cropping systems (rice-maize-wheat-mungbean) in North-West India face challenges from inefficient flood irrigation, leading to nitrogen (N) losses via leaching, volatilization and denitrification, which reduce nitrogen use efficiency (NUE). Conservation agriculture (CA) practices like zero tillage and residue retention, combined with sub-surface drip irrigation (SSDI), offer potential to optimize N dynamics by targeting delivery to the root zone. For this study ongoing experiment of CIMMYT (International Maize and Wheat Improvement Centre) – ICAR-CSSRI (Indian Council of Agricultural Research-Central Soil Salinity Research Institute) strategic research platform, located at ICAR-CSSRI, Karnal with geographic coordinates of 29◦42′′ 20.7′ N toward latitude, 76◦57′′19.79′ E toward longitude and at an elevation of 243 m above mean sea level, Haryana, India was investigated. The objective of this study was evaluate impact of sub-surface drip irrigation (SSDI) versus flood irrigation on soil Nitrogen (NH₄⁺-N and NO₃⁻-N) distribution under six cropping scenarios (Sc): Sc1—conventional puddled transplanted rice (TPR) followed by conventional tilled (CT) wheat with residue removal; Sc2—TPR followed by zero-till (ZT) wheat and ZT-mungbean with partial residue retention; Sc3—direct-seeded rice (DSR) followed by ZT-wheat and ZT-mungbean with full residue retention; Sc4—ZT-maize replacing DSR, followed by ZT-wheat and ZT-mungbean; Sc5— direct-seeded rice (DSR) followed by ZT-wheat and ZT-mungbean with full residue retention integrated with sub-surface drip irrigation (SSDI) and Sc6— ZT-maize replacing DSR, followed by ZT-wheat and ZT-mungbean , respectively and across depths (0-5, 5-15, 15-30, 30-50, 50-75, 75-100 cm). SSDI maintained higher soil moisture (25-35%) and ammonical and nitrate nitrogen (NH₄+/NO₃⁻-N) concentrations The CA practices increased ammonium (NH₄⁺-N) and nitrate (NO₃⁻-N) concentrations at surface soil depths. In CA-based rice and maize systems, SSDI showed higher NH₄⁺/NO₃⁻-N at 15-30 cm during the first observation compared to flood irrigation minimizing deep leaching. However, under wheat, surface soils exhibited elevated NH₄⁺/ NO₃⁻-N under both irrigation systems. Wheat leaves showed higher nitrogen concentration under SSDI compared to flood irrigation, while stems exhibited greater N under flood systems. Roots displayed significantly higher N concentration in the rice-wheat-mungbean + SSDI than in the maize-wheat-mungbean + SSDI system. Overall, maize-wheat-mungbean system under SSDI performed better in terms of NUE and system productivity.