Integrated nutrient management

1. Introduction

Modern agriculture faces a major challenge — to increase crop productivity while maintaining soil fertility and minimizing environmental degradation.
Excessive dependence on chemical fertilizers has led to soil nutrient imbalance, decline in organic matter, and deterioration of soil health.
To overcome these issues, the concept of Integrated Nutrient Management (INM) has emerged as a sustainable solution.

2. Meaning / Definition

• Integrated Nutrient Management (INM) refers to the judicious and combined use of chemical fertilizers, organic manures, and bio-fertilizers to maintain soil fertility and to supply plant nutrients for optimum crop productivity in an ecologically sustainable manner.
• FAO (1990) Definition: “INM is the maintenance and adjustment of soil fertility and plant nutrient supply to an optimum level for sustaining desired crop productivity through the judicious and balanced use of all sources of plant nutrients — inorganic, organic, and biological — in an integrated manner.”

3. Objectives of INM

• To maintain soil fertility and sustain crop productivity.
• To ensure efficient and balanced use of nutrients.
• To minimize the use of chemical fertilizers and reduce production cost.
• To improve soil physical, chemical, and biological properties.
• To reduce environmental pollution due to fertilizer misuse.
• To increase nutrient use efficiency (NUE).
• To promote recycling of organic residues and farm wastes.
• To achieve sustainable agricultural production.

4. Concept of INM

INM integrates three major sources of plant nutrients:

The principle of INM is to combine all these sources in a balanced proportion depending on soil fertility, crop requirement, and local resource availability.

5. Components of INM

• Chemical Fertilizers: Supply major nutrients (N, P, K) quickly. Should be applied in balanced and need-based doses.
• Organic Manures: Examples: FYM, compost, green manure, press mud, crop residues. Supply secondary and micronutrients, improve soil organic matter.
• Bio-fertilizers: Examples: Rhizobium, Azospirillum, Azotobacter, PSB, VAM fungi. Enhance nutrient availability and soil microbial activity.
• Soil Amendments: Lime (for acid soils), gypsum (for sodic soils). Improve soil condition for better nutrient uptake.
• Crop Rotation and Residue Management: Legume inclusion improves N status. Residue recycling maintains organic matter.

6. Approaches / Strategies of INM

Integrated Nutrient Management can be achieved through several complementary approaches. These approaches vary depending on soil fertility, cropping system, and resource availability.

• Soil Test-Based Fertilizer Use; Fertilizer doses are determined based on soil testing. Prevents over- or under-application of nutrients. Example: Use of Soil Health Card Scheme in India.
• Balanced Fertilization; Applying nutrients in correct proportion and ratio (N:P:K) based on crop requirements. Avoids nutrient imbalance (e.g., excessive N leads to P and K deficiency).
• Combined Use of Organic and Inorganic Sources; Using FYM + Fertilizers + Bio-fertilizers together for synergistic effect. Example: 50% N through FYM + 50% N through urea. Improves soil organic carbon and fertilizer efficiency.
• Site-Specific Nutrient Management (SSNM); Nutrient application is tailored to specific fields and crops. Based on variability in soil fertility, cropping history, and yield potential. Uses tools like Leaf Color Chart (LCC), GreenSeeker, and N-sensors.
• Integrated Plant Nutrient System (IPNS); Similar to INM but emphasizes nutrient recycling from all available sources (crop residues, animal manure, compost, green manure, etc.).
• Inclusion of Legumes in Cropping Systems; Incorporating pulses or green manures (e.g., dhaincha, sunhemp) in rotations improves nitrogen availability through biological fixation.
• Recycling of Organic Residues; Using crop residues, sugarcane trash, press mud, poultry litter, etc., as composted organic sources. Enhances soil microbial activity and nutrient cycling.

Use of Bio-fertilizers

• Applying suitable bio-fertilizers such as:
  • Rhizobium for pulses.
  • Azospirillum for cereals.
  • PSB for all crops.
  • VAM fungi for phosphorus mobilization.

7. Advantages of Integrated Nutrient Management

8. Example of INM Practice (Rice–Wheat System)

→ INM ensures sustained productivity and soil health compared to fertilizer-only systems.

Constraints in Adoption of INM

• Lack of awareness and training among farmers.
• Non-availability of quality organic manures and bio-fertilizers.
• Difficulty in transport and application of bulky organic materials.
• Limited research-extension linkage.
• Slow response compared to chemical fertilizers.

Government Initiatives Promoting INM in India

• National Mission on Sustainable Agriculture (NMSA) – Promotes INM practices.
• Soil Health Card Scheme (2015) – Encourages soil test–based fertilizer use.
• Paramparagat Krishi Vikas Yojana (PKVY) – Promotes organic and integrated nutrient management.
• National Project on Organic Farming (NPOF) – Supports bio-fertilizer and compost production.
• Integrated Nutrient Management Division (INM Division, DAC&FW) – Coordinates national INM strategies and training.