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<p>Nitrogen (N) is a critical nutrient for forage crop production, influencing yield, quality, and nitrogen use efficiency (NUE). Traditional blanket fertilizer recommendations often fail to account for spatial and temporal variability in crop N requirements, leading to sub-optimal yields and environmental risks.&#xa0;We conducted an experiment over three years (2018–2021) at ICAR–IGFRI, Jhansi, India, to evaluate SPAD- and Leaf Color Chart (LCC)-based real-time N management strategies in two oat varieties (JHO-822 and JHO-2012-2). The objective was to determine the relationship between SPAD and LCC scores with leaf N concentration and dry matter (DM) yield, and to identify threshold values for optimized N application. Oat variety JHO-2012-2 was consistently superior over JHO-822 in terms of DM yield (9.3% to 18.9% across years), crude protein (CP) content, and N use efficiency (NUE). SPAD-based N application, especially SPAD45, significantly improved DM yield (6.7% to 20.8%), CP yield (16.9%), and net returns over the conventional practice, with SPAD35 offering a balance between yield and nitrogen savings. Threshold values of SPAD 40 and LCC 4.5 were established as optimal for guiding topdressing to achieve 90% of maximum yield. Lower thresholds (SPAD30, SPAD35) yielded higher partial factor productivity and physiological efficiency, while higher thresholds (SPAD40, SPAD45) improved recovery efficiency and forage quality by reducing fiber content. Economic analysis revealed that SPAD45 maximized benefit-cost ratio (2.65) and net returns, supporting its potential for profitable and sustainable forage production.&#xa0;This study validates SPAD and LCC tools for precision N management in forage oat, enhancing yield, quality, NUE, and profitability. Notably, it provides the first evidence on LCC-based nitrogen management in oat, offering a low-cost alternative for smallholders. Adoption of these tools can significantly contribute to fertilizer savings and promote the sustainable intensification of fodder systems in India and abroad.</p>

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Optimizing Nitrogen Fertilization in Oat Using the Chlorophyll Meter: Threshold Determination for Yield, Fodder Quality and Nitrogen Use Efficiency

  • 期刊论文

  • 发表日期：

    2026年2月2日

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  • Mukesh Choudhary,
  • Prabhu Govindasamy,
  • Anoop Kumar Dixit,
  • Sita Ram Kantwa,
  • Asha Ram,
  • Dana Ram Palsaniya,
  • Sunil Kumar

摘要

Nitrogen (N) is a critical nutrient for forage crop production, influencing yield, quality, and nitrogen use efficiency (NUE). Traditional blanket fertilizer recommendations often fail to account for spatial and temporal variability in crop N requirements, leading to sub-optimal yields and environmental risks. We conducted an experiment over three years (2018–2021) at ICAR–IGFRI, Jhansi, India, to evaluate SPAD- and Leaf Color Chart (LCC)-based real-time N management strategies in two oat varieties (JHO-822 and JHO-2012-2). The objective was to determine the relationship between SPAD and LCC scores with leaf N concentration and dry matter (DM) yield, and to identify threshold values for optimized N application. Oat variety JHO-2012-2 was consistently superior over JHO-822 in terms of DM yield (9.3% to 18.9% across years), crude protein (CP) content, and N use efficiency (NUE). SPAD-based N application, especially SPAD45, significantly improved DM yield (6.7% to 20.8%), CP yield (16.9%), and net returns over the conventional practice, with SPAD35 offering a balance between yield and nitrogen savings. Threshold values of SPAD 40 and LCC 4.5 were established as optimal for guiding topdressing to achieve 90% of maximum yield. Lower thresholds (SPAD30, SPAD35) yielded higher partial factor productivity and physiological efficiency, while higher thresholds (SPAD40, SPAD45) improved recovery efficiency and forage quality by reducing fiber content. Economic analysis revealed that SPAD45 maximized benefit-cost ratio (2.65) and net returns, supporting its potential for profitable and sustainable forage production. This study validates SPAD and LCC tools for precision N management in forage oat, enhancing yield, quality, NUE, and profitability. Notably, it provides the first evidence on LCC-based nitrogen management in oat, offering a low-cost alternative for smallholders. Adoption of these tools can significantly contribute to fertilizer savings and promote the sustainable intensification of fodder systems in India and abroad.