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As we know soil testing is crucial before planting and for on-going crops management to assess nutrient balance and soil pH, which affects nutrient availability. However, soil tests may not always represents the actual nutrient levels in the plants.

For example, a soil high in a certain nutrient might not translate to high levels in the plants, or the plants might have adequate nutrients despite a soil test indicating a deficiency. Factors like plants growth, soil characteristics (such as pH and compaction), and environmental conditions (like rainfall or drought) can impact this discrepancy. Therefore, while petiole analysis is generally more reliable for evaluating plants nutrient status. Combining both soil and plant tests offers the most accurate picture of fertility and necessary adjustments during crop production.

• Recommended Analysing parameters

Total content of Macronutrients (Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulfer), and Micronutrients (Iron, Manganese, Zinc, Copper, Boron, and Mollybdenum etc). Additionally, any other parameters are also analysed according to requirement.

• Movement of ionic forms of nutrients:

For making effective INM schedule the knowledge of movement of ionic forms of nutrients in soil and plant system should be known for their availability and uptake pattern.

• Highly mobile: N, P and K
• Moderately mobile: Zn
• Less mobile: S, Fe, Mn, Cl, Mo and Cl
• Immobile: Calcium and Boron

• There are three main methods to check nutrient status: -

1. Soil tests to know the nutrient status of soil.
2. Visual deficiency symptoms on plant by observations.
3. Analysing plant tissue samples (Petioles and Leaf analysis)

• Analysing plant tissue (petioles and plant leaf) samples.

As we know, soil is the storehouse of nutrients and water for plants, similarly, petioles and leaves are storehouse of nutrients within the plant body. Among the above-mentioned methods, plant tissue analysis is the best way to monitor nutrient levels and requirements for higher yields while crops are standing in the field. By directly tracking the deficient plant nutrients, farmers can adjust their fertilizer programs and potentially reducing costs on excess. We accurate identification is essential for effective fertilizer management.

For tissue analysis, we use different plant parts as a sample, such as petioles and leaf blades. However, petiole analysis and leaf blades are most preferred for nutrient assessment. Basically, the plant analysis has been done for more commercial crops to prevent the production losses due to nutrient deficiency.

• In Which crops/plant petioles and leaf testing mostly carried out.

Plant tissue testing mostly performed in: -

• Fruits crops: - Grapes, Pomegranate, Banana, Strawberry, Mango, Citrus, Orange, Fig, Coconut, Cashew nuts, Areca nuts, Sapota, Ber, Apple.
• Vegetables Crops: - Tomato, Chilli, Onion, Brinjal Potato and other crops.
• Agronomic Crops: - Cotton, Sugarcane, Maize, Sorghum etc. and other crops and medicinal plants according to requirements.

• Timing of Petiole Sampling (Important Stages): -

• Troubleshooting foliar symptoms: Identify leaf symptoms and suspect a nutrient deficiency, gather petiole along with leaf samples from plant displaying leaf symptoms and from healthy asymptomatic plant. Send and analyse the two samples separately for comparison. This approach will help in diagnosing whether the issue is linked to the plant nutrient status. For troubleshooting, we can collect samples whenever leaf symptoms emerge during the growing season.
• Full bloom: Sampling conducted during 75% flowering of crops/plants. Bloom time sampling may be useful as a follow-up to nutrient adjustments during the previous season. Samples of petioles and leaves are collected from leaves that are opposite to inflorescences
• Fruiting Stage (Veraison): - It is the ideal time for routine petiole sampling. This is due to the increased stability of nutrient concentrations relative to earlier in the season during bloom.

• Troubleshooting foliar symptoms: Identify leaf symptoms and suspect a nutrient deficiency, gather petiole along with leaf samples from plant displaying leaf symptoms and from healthy asymptomatic plant. Send and analyse the two samples separately for comparison. This approach will help in diagnosing whether the issue is linked to the plant nutrient status. For troubleshooting, we can collect samples whenever leaf symptoms emerge during the growing season.
• Full bloom: Sampling conducted during 75% flowering of crops/plants. Bloom time sampling may be useful as a follow-up to nutrient adjustments during the previous season. Samples of petioles and leaves are collected from leaves that are opposite to inflorescences
• Fruiting Stage (Veraison): - It is the ideal time for routine petiole sampling. This is due to the increased stability of nutrient concentrations relative to earlier in the season during bloom.

According to growth stages and types of crops/plants the recommended plant parts are different. Here we provide some recommendations of time and plant parts for nutrients analysis in important plants/crops.

(Source: Bhargava,B.S., 1999. Leaf analysis for diagnosing nutrients need in fruit crops)

• How plant leaf/petiole samples sent to laboratory for analysis: -

• The sample must be packed in clean paper bags to prevent external contamination.
• The sample bags should be labled properly with all necessary information.
• Sample should be sent to lab as early as possible (within 3 days of sampling)