Nutrient use efficiency

1. Introduction

• Nutrient Use Efficiency (NUE) is a critical concept in soil fertility management and sustainable agriculture. It determines how effectively plants utilize supplied nutrients (from fertilizers, manures, or soil reserves) to produce economic yield.
• Improving NUE is essential to increase crop productivity, reduce fertilizer wastage, minimize environmental pollution, and enhance profitability.

2. Definition

• Nutrient Use Efficiency (NUE) is the ratio between the amount of nutrient taken up by the plant and the amount of nutrient applied to the soil.
• “The ability of plants to utilize available nutrients efficiently for growth, yield, and quality.”

3. Importance of Nutrient Use Efficiency

• Enhances crop productivity and profitability.
• Reduces nutrient losses through leaching, volatilization, and runoff.
• Minimizes environmental pollution (e.g., nitrate leaching, eutrophication).
• Improves fertilizer economy by maximizing return per unit nutrient applied.
• Promotes sustainable soil fertility management.
• Essential for Integrated Nutrient Management (INM) and precision agriculture.

4. Conceptual Framework of NUE

Nutrient Use Efficiency is influenced by several interacting factors:

5. Components / Types of Nutrient Use Efficiency

NUE can be divided into several components to better understand where losses or inefficiencies occur.

• Example (Nitrogen Use Efficiency): If 120 kg N/ha is applied and the crop takes up 60 kg N/ha more than control:
• Recovery Efficiency (RE) = (60 ÷ 120) × 100 = 50%. That means only half of the applied nitrogen was absorbed by the plant; the rest was lost or remained unused.

6. Average Nutrient Use Efficiencies in India

Thus, on average, only about 30–40% of applied fertilizers are utilized by crops; the rest is lost to the environment.

• Factors Affecting Nutrient Use Efficiency

a) Soil Factors

• Soil pH (acidic or alkaline conditions affect availability).
• Soil organic matter and microbial activity.
• Soil moisture and temperature.
• Soil texture and structure.
• Nutrient interactions (e.g., N-P-K balance).

b) Crop Factors

• Root system and nutrient uptake efficiency.
• Genetic characteristics (varietal differences).
• Crop age and growth stage.
• Crop rotation and residue management.

c) Fertilizer Management Factors

• Type and form of fertilizer (e.g., urea vs. ammonium nitrate).
• Rate, method, and timing of application.
• Use of inhibitors or slow-release formulations.
• Integration with organic and biofertilizers.

d) Environmental Factors

• Rainfall (causes leaching).
• Temperature (affects microbial activity).
• Wind (causes volatilization losses).

Ways to Improve Nutrient Use Efficiency

a) Agronomic Practices

• Balanced Fertilization: Apply nutrients in recommended N:P:K ratios. Avoid excess nitrogen without matching P and K.
• Split Application: Apply fertilizers in multiple doses to match crop demand (especially N).
• Proper Timing and Placement: Place fertilizers near root zone instead of broadcasting. Apply at critical growth stages (e.g., tillering, flowering).
• Use of Soil Testing and Leaf Analysis: Determine actual nutrient requirement.
• Crop Rotation and Intercropping: Include legumes to fix nitrogen and improve soil fertility.

b) Technological Approaches

• Neem-Coated Urea: Slows nitrogen release and reduces volatilization. Improves nitrogen recovery efficiency by 10–15%.
• Slow and Controlled Release Fertilizers: Examples: Sulphur-coated urea, polymer-coated fertilizers.
• Nitrification and Urease Inhibitors: Examples: Nitrapyrin, DCD (dicyandiamide), NBPT. Reduce N losses via denitrification and volatilization.
• Fertigation: Application of fertilizers through drip/sprinkler irrigation for precision delivery.
• Site-Specific Nutrient Management (SSNM): Adjusting fertilizer use based on real-time nutrient status of soil and crop.
• Nano-Fertilizers: High efficiency, slow release, minimal losses.