Precision nitrogen and water management in double zero -till wheat: effects on photosynthetic parameters, productivity, nutrient-use efficiency and N2O emission

Anchal Dass^1*VIJAY PRATAP^2,3P Krishnan³S Sudhishri³Arti Bhatia³Dinesh Jinger⁴Sunil K Verma⁵Arjun Singh^3*Aye Aye San^3*KADAGONDA NITHINKUMAR³R Sadhukhan⁶Sandeep Kumar⁷Venkatesh Paramesh⁸Teekam Singh³Ramanjit Kaur³Shiv Poojan Yadav⁹

• ¹Division of Agronomy, Indian Council of Agricultural Research (ICAR), New Delhi, India
• ²Raja Balwant Singh College Agra, Agra, India
• ³ICAR - Indian Agricultural Research Institute, New Delhi, India
• ⁴ICAR - Indian Institute of Soil and Water Conservation Chandigarh, Chandigarh, India
• ⁵Banaras Hindu University, Varanasi, India
• ⁶Central Agricultural University, Imphal, India
• ⁷ICAR National Bureau of Soil Survey & Land Use Planning, Nagpur, India
• ⁸ICAR - Central Coastal Agricultural Research Institute, Ela, India
• ⁹Acharya Narendra Deva University of Agriculture & Technology, Ayodhya, India

CONTEXT: Conventional tillage (CT), excessive irrigation, and indiscriminate nitrogen (N) use in wheat farming degrade soil and water resources in the Indo-Gangetic Plains (IGP), threatening the sustainability of the rice-wheat cropping system. OBJECTIVES: A two-year study (2019–21) in north-west IGP was conducted to assess the integration of zero-tillage (ZT) with precision water and N management for sustainability, nutrient efficiency, and environmental performance. METHODS: The study tested two crop establishment methods (ZT-wheat and double ZT-wheat) and three irrigation regimes–25%, 50%, and 75% depletion of available soil moisture (DASM), with silicon applied at 75% DASM–alongside three N strategies: 100% recommended N dose (RDN), NutrientExpert® (NE®) + Leaf Colour Chart (LCC), and NE® + SPAD-based N management, using a split-plot design. RESULTS AND CONCLUSION: Double ZT-wheat performed better over conventional ZT, showed superior growth (higher dry matter accumulation, leaf area index, and photosynthetic rate), 3.5% greater interception of photosynthetically active radiation (PAR), and 6.7–9.9% increases in grain/straw yields, and resource-use efficiency. Irrigation at 25% DASM increased photosynthetic activity, intercepted 18.3% more PAR, and yielded 9.23% higher grain over 50% DASM, though delaying irrigation to 50% DASM conserved water without significant yield loss. NE® + SPAD-based N management saved 40 kg N ha–1 while enhancing productivity and efficiency, and combining ZT with 75% DASM + silicon and NE® + LCC significantly reduced N₂O emissions, thus suggested for implementation in the wheat growing regions. SIGNIFICANCE: The current study findings promote precision N-water strategies, and double ZT to enhance productivity, resource conservation, and environmental sustainability in the IGP's wheat systems addressing important sustainable development goals concerning agriculture.