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<p>This study evaluated how twenty years of contrasting nutrient management practices regulate soil microbial processes, enzyme activities, and nutrient cycling in a pearl millet-wheat cropping system.&#xa0;A long-term field experiment at ICAR-IARI, New Delhi, evaluated twenty years of nutrient management involving farmyard manure (FYM), soil test crop response (STCR)-based fertilization, integrated STCR + FYM, recommended dose of fertilizers (RDF), and an unfertilized control in a pearl millet–wheat system. Surface soils (0–15&#xa0;cm) were analysed for extracellular enzyme activities, microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), stoichiometric ratios, and composite biological indices. Principal component analysis (PCA), random forest modelling, and regression analyses were used to identify important drivers of soil biological functioning.&#xa0;Microbial biomass increased significantly, with MBC ranging from 162&#xa0;mg kg⁻¹ (Control) to 299&#xa0;mg kg⁻¹ (FYM at 20 t ha⁻¹). Enzyme activities were strongly correlated with MBC (<i>r</i> = 0.86–0.92; <i>p</i> &lt; 0.001), reflecting close coupling between microbial biomass and biochemical functioning. PCA explained 86.3% of variability, distinctly separating FYM and integrated STCR treatments along a high biological activity gradient. Random forest modelling identified GMea, urease, β-glucosidase, and dehydrogenase as most influential variables differentiating nutrient management treatments under long-term conditions, while regression (R² = 0.895) highlighted dehydrogenase and arylsulphatase as major determinants of MBC.&#xa0;Long-term application of farmyard manure and its integration with soil test–based fertilization enhances soil microbial biomass, enzyme activities, and functional biological properties in semi-arid inceptisols. These findings highlight the importance of combining organic amendments with targeted fertilization strategies to sustain soil health and nutrient cycling in intensive cereal-based systems.</p> Graphical Abstract <p></p>

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Two Decades of Nutrient Management Improves Soil Microbial Processes Regulating Carbon and Nutrient Cycling in a Pearl Millet–Wheat System in Semi-Arid Alluvial Soils

  • 期刊论文

  • 发表日期：

    2026年7月11日

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  • Sharat Kothari,
  • Vinod Kumar Sharma,
  • K. M. Manjaiah,
  • Indu Chopra,
  • Debarup Das,
  • C. M. Parihar,
  • Kadooran Abshiba,
  • Prince Kumar,
  • Kapil A. Chobhe,
  • Mandira Barman

摘要

This study evaluated how twenty years of contrasting nutrient management practices regulate soil microbial processes, enzyme activities, and nutrient cycling in a pearl millet-wheat cropping system. A long-term field experiment at ICAR-IARI, New Delhi, evaluated twenty years of nutrient management involving farmyard manure (FYM), soil test crop response (STCR)-based fertilization, integrated STCR + FYM, recommended dose of fertilizers (RDF), and an unfertilized control in a pearl millet–wheat system. Surface soils (0–15 cm) were analysed for extracellular enzyme activities, microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), stoichiometric ratios, and composite biological indices. Principal component analysis (PCA), random forest modelling, and regression analyses were used to identify important drivers of soil biological functioning. Microbial biomass increased significantly, with MBC ranging from 162 mg kg⁻¹ (Control) to 299 mg kg⁻¹ (FYM at 20 t ha⁻¹). Enzyme activities were strongly correlated with MBC (r = 0.86–0.92; p < 0.001), reflecting close coupling between microbial biomass and biochemical functioning. PCA explained 86.3% of variability, distinctly separating FYM and integrated STCR treatments along a high biological activity gradient. Random forest modelling identified GMea, urease, β-glucosidase, and dehydrogenase as most influential variables differentiating nutrient management treatments under long-term conditions, while regression (R² = 0.895) highlighted dehydrogenase and arylsulphatase as major determinants of MBC. Long-term application of farmyard manure and its integration with soil test–based fertilization enhances soil microbial biomass, enzyme activities, and functional biological properties in semi-arid inceptisols. These findings highlight the importance of combining organic amendments with targeted fertilization strategies to sustain soil health and nutrient cycling in intensive cereal-based systems.

Graphical Abstract