Optimizing Soil Health and Productivity in Intensive Rice-Wheat Systems Using Conjoint Application of Sewage Sludge

Area of Science:

• Agricultural Science
• Soil Science
• Environmental Science

Background:

• Intensive rice-wheat cropping systems (RWCS) often rely heavily on synthetic fertilizers, impacting soil health and sustainability.
• Sewage sludge (SSL) offers a potential nutrient source for improving soil properties and reducing fertilizer dependency.
• Long-term studies are crucial to assess the sustainability of integrating SSL with chemical fertilizers in RWCS.

Purpose of the Study:

• To evaluate the long-term effects of integrating sewage sludge (SSL) with recommended (100%) or reduced (75%) chemical fertilizer doses.
• To enhance soil health, crop productivity, and reduce synthetic fertilizer dependency in RWCS.
• To identify key soil health indicators (SHIs) and develop a soil health index (SHI) for assessing treatment effectiveness.

Main Methods:

• A field experiment was conducted in Uttar Pradesh, India, from 2010 to 2020.
• Nine nutrient management treatments were applied in a randomized complete block design, including sole recommended dose of fertilizers (RDF) and combinations of SSL (20 or 30 t ha⁻¹) with 100% or 75% RDF.
• Soil physicochemical and biological properties were analyzed to compute SHIs.

Main Results:

• Integrated treatments significantly outperformed sole RDF in terms of productivity and soil health index (SHI).
• Treatments T₃ (100% RDF + 30 t ha⁻¹ SSL), T₂ (100% RDF + 20 t ha⁻¹ SSL), and T₉ (75% RDF + 30 t ha⁻¹ SSL) showed the highest productivity and SHI (0.85-1.0).
• Alkaline phosphatase, available K, and microbial biomass N were identified as sensitive SHIs. Treatment T₃ improved soil organic carbon, water-holding capacity, and nutrient levels while reducing bulk density, staying within heavy metal thresholds.

Conclusions:

• Integrating sewage sludge with chemical fertilizers is a sustainable strategy for enhancing soil health and crop productivity in RWCS.
• Optimized application of SSL, particularly with reduced fertilizer doses, can significantly improve soil properties and reduce reliance on synthetic inputs.
• This integrated approach promotes resilient agricultural systems aligned with UN Sustainable Development Goals.