Soil's chemical properties significantly influence its fertility and ability to support plant growth. Key chemical parameters include pH, electrical conductivity, organic matter, and nutrient levels.

1. Soil pH:
2. Definition: A measure of soil acidity or alkalinity, ranging from 0 to 14.
3. Classification:
4. Acidic: pH < 7
5. Neutral: pH = 7
6. Alkaline: pH > 7
7. Impact on Plants:
8. Affects nutrient availability.
9. Optimal range for most crops is 6.0–7.5.
10. Measurement:
11. Use a pH meter or indicator strips.
12. Mix 10 g of soil with 25 mL of distilled water, let it settle, and test the liquid.
13. Electrical Conductivity (EC):
14. Definition: Measures the soil’s salinity level, indicating the concentration of soluble salts.
15. Units: MilliSiemens per centimeter (mS/cm).
16. Impact on Plants:
17. High EC can harm crops by reducing water uptake.
18. Ideal range: 0.2–1.0 mS/cm for most crops.
19. Measurement:
20. Mix soil and distilled water in a 1:2 ratio.
21. Insert the EC probe into the solution and record the reading.
22. Soil Organic Matter (SOM):
23. Definition: Decomposed plant and animal residues in soil.
24. Impact on Plants:
25. Improves soil structure, water retention, and nutrient supply.
26. Enhances microbial activity.
27. Measurement:
28. Burn soil in a muffle furnace to calculate organic matter content.
29. Nutrient Content:
30. Primary Nutrients:
31. Nitrogen (N): Promotes leafy growth.
32. Phosphorus (P): Supports root development and flowering.
33. Potassium (K): Enhances disease resistance and overall health.
34. Secondary Nutrients:
35. Calcium, Magnesium, Sulfur.
36. Micronutrients:
37. Iron, Manganese, Zinc, Copper, Boron.
38. Measurement:
39. Use chemical extraction methods followed by spectrophotometry.

1. Nutrient Availability:
2. pH affects the solubility of nutrients.
3. Proper management ensures nutrients are accessible to plants.
4. Crop Selection:
5. Certain crops prefer specific pH ranges (e.g., potatoes thrive in slightly acidic soils, while alfalfa prefers alkaline soils).
6. Fertilizer Application:
7. Chemical properties guide the type and amount of fertilizer to use.

1. Parent Material:
2. The mineral composition of the parent rock affects nutrient content.
3. Organic Matter:
4. Decomposed material contributes to nutrient levels.
5. Land Management:
6. Overuse of fertilizers and chemicals can alter pH and EC.
7. Climate:
8. Rainfall leaches nutrients, making soil acidic over time.

1. Acidic Soil:
2. Impact: Nutrient deficiencies and toxicity.
3. Solution: Apply lime to increase pH.
4. Alkaline Soil:
5. Impact: Reduced availability of micronutrients like iron and zinc.
6. Solution: Add sulfur or organic matter to lower pH.
7. Saline Soil:
8. Impact: High EC harms crop growth.
9. Solution: Improve drainage and leach salts with water.

Objective: Measure soil pH, EC, and nutrient levels.

Steps:

1. Measuring pH:
2. Take 10 g of soil in a beaker.
3. Add 25 mL of distilled water and stir.
4. Allow the solution to settle for 10 minutes.
5. Insert the pH probe and record the reading.
6. Measuring Electrical Conductivity (EC):
7. Mix 10 g of soil with 20 mL of distilled water.
8. Stir the mixture and let it settle.
9. Insert the EC meter probe and note the value.
10. Testing Organic Matter:
11. Weigh a soil sample and place it in a muffle furnace at 400°C.
12. After 4 hours, reweigh the sample to determine organic matter loss.
13. Nutrient Analysis:
14. Use chemical extraction kits to test for nitrogen, phosphorus, and potassium.
15. Follow instructions for reagent preparation and colorimetric analysis.

Key Takeaways

1. Soil chemical properties like pH, EC, organic matter, and nutrient levels significantly impact soil fertility.
2. Measuring and managing these properties ensures optimal crop growth and sustainable farming.
3. Proper techniques and equipment are essential for accurate analysis.