Soil Science Important Points
Exam Oriented Points
1. General Recommended Fertilizer Doses (N:P:K Ratio)
| Crop Group | Recommended N:P:K Ratio |
|---|---|
| Cereal Crops (अनाज फसलें) | 4 : 2 : 1 |
| Pulse Crops (दलहनी फसलें) | 1 : 2 : 1 or 1 : 2 : 2 |
| Oilseed Crops (तिलहनी फसलें) | 3 : 2 : 1 |
| Fodder/Fiber Crops (चारा/रेशा फसलें) | 2 : 1 : 4 |
| Root Crops (जड़ वाली फसलें) | 2 : 1 : 1 |
General agronomy recommendation / standard agriculture guidelines
2.Classification of Irrigation Projects (Based on CCA)
CCA: – Culturable Commend Area
| Project Type | CCA (hectare) | Project Cost (Rs.) |
|---|---|---|
| Major Irrigation Project | More than 10,000 ha | More than ₹50 Crore |
| Medium Irrigation Project | 2,000 – 10,000 ha | ₹25 Lakh – ₹5 Crore |
| Minor Irrigation Project | Less than 2,000 ha | Less than ₹25 Lakh |
3.Composition of atmospheric air
| Gas | Volume in Air |
|---|---|
| Nitrogen (N₂) | 78.08% |
| Oxygen (O₂) | 20.95% |
| Argon (Ar) | 0.93% |
| Carbon Dioxide (CO₂) | 0.03% |
4.Character of Saline & Alkaline Soil
| Character | Saline Soil | Alkaline Soil | Saline-Alkaline |
| ESP | <15% | >15% | >15% |
| EC(dSm) at 25°C | >4% | <4% | >4% |
| pH | <8.5 | >8.5 | >8.5 |
ESP = Exchangable sodium percentage
EC = Electricity conductivity
pH = power of hydrogen
📌 Important Notes (Students ke liye)
- Saline soil → high soluble salts, low sodium hazard.
- Alkaline (Sodic) soil → high sodium content, poor soil structure.
- Saline–alkaline soil → high salts + high sodium dono.
- ESP = Exchangeable Sodium Percentage
- EC = Electrical Conductivity (soil salinity measure)
5.Pf value
-
pF Value (Soil Water Retention Force)
👉 pF = Log₁₀ of soil water suction (cm water column)
👉 Soil water ko soil kitni force se hold karti hai uska measure.
| Soil condition | Pressure (atm/bars) | Pf value |
| Saturated soil | 0.001 | 0 |
| Field capacity | 1/3 | 2.53 |
| PWP | 15 | 4.18 |
| Hygroscopic point | 31 | 4.5 |
| Oven dry soil | 10,000 | 7 |
PWP = Permanent wilting Point
6.Measurement of irrigation water:
| 1 Cusec | 28.3 liters |
| 1 Cumec | 1000 liters or 103 |
| 1 ha mm | 10,000 liters 104 |
| 1 ha cm | 100,000 liters or 105 |
| 1 ha m | 100,000,00 liters or 107 |
7.Carbon Nitrogen (C:N) Ratio
| C:N Ratio of Material | C:N Ratio |
| Humus | 10:1 |
| Normal soils | 8:1 to 15:1 |
| Legumes | 20:1 to 30:1 |
| Cereals | 90:1 |
| FYM | 25:1 to 30:1 |
| Sawdust | 400:1 (Highest) |
| Micro-organism | 4:1 to 9:1 (Lowest) |
8. Equivalent Acidity of Fertilizers
Equivalent Acidity: The amount of CaCO3 required to neutralise the acid residues caused by acidic fertilizers in the soil e.g. 100 kg (NH4)2SO4 produces acidity which needs 110 kg of CaCO3 to neutralist it. Therefore equivalent acidity of (NH4)2SO4 is 110; Anhydrous NH3 has more equivalent acidity than other fertilizers.
👉 Equivalent Acidity: Acidic fertilizer se soil me bani acidity ko neutralize karne ke liye required CaCO₃ (kg per 100 kg fertilizer).
| Fertilizers | Equivalent Acidity |
| Anhydrous ammonia | 148 (Highest) |
| Ammoniunm chloride (NH4CI) | 128 |
| Ammonium sulphate (NH4)2SO4 | 110 |
| Ammonium sulphate nitrate (NH4)2SO4NH4NO3 | 93 |
| Urea | 80 – 85 |
| DAP | 77 |
| Ammonium nitrate (NH4NO3) | 60 |
| Mono-ammonium Phosphate | 55 (Lowest) |
9.Equivalent Basicity of Fertilizers
Equivalent Basicity: Residual basicity caused by application of basic fertilizers, expressed in terms of CaCO3 equivalent of basic residues left by a fertilizer material (in kg/100 kg of fertilizer salt).
👉 Equivalent Basicity: Basic fertilizers se soil me bachi basic residue (CaCO₃ equivalent).
| Fertilizers | Equivalent basicity |
| Calcium cyanamide (CaCN2) | 63 |
| Sodium nitrate (NaNO3) | 29 |
| Potassium nitrate (KNO3) | 29 |
| Nitrate of Soda Potash | 26 |
| Calcium nitrate Ca(NO3) | 21 |
10. Plants used for nutrient deficiency indicator
| Nutrients | Indicator plant |
| Nitrogen | Cauliflower, Cabbage |
| Phosphorus | Mustard, Rapeseed |
| Potassium | Potato |
| Calcium | Cauliflower, Cabbage |
| Boron | Sunflower, Sugar-beet |
| Sodium | Sugar beet, Turnip |
| Chlorine | Lettuce |
| Ferrous | Sorghum, Citrus, Barley |
| Copper | Wheat |
| Magnesium | Potato, Cauliflower, Sugar beet |
| Manganese | Sugar beet, Apple, Apricot |
| Molybdenum | Cauliflower |
| Zinc | Maize |
11.Sources of plant nutrients
| Nutrients | Sources |
| Nitrogen (N) | Organic Matter |
| Phosphorus (P) | Appetite |
| Potassium (K) | Biotite, Orthoclase |
| Calcium (Ca) | Anorthite, Dolomite |
| Magnesium(Mg) | Dolomite, Olivine |
| Manganese (Mn) | Pyrolusite |
| Ferrous (Fe) | Pyrite |
| Boron(B) | Tourmaline |
| Molybdenum (Mo) | Olivine |
.Note:- More important soil Science Table Upload Soon
👉 Test Your Knowledge with MCQs Click
| Important Table – 1 | Cl;ick |
| Important Table – 2 | Cl;ick |
| One Liner | Cl;ick |
| Fertilizers classification | Cl;ick |
Soil Science Important Points
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Small correction:- pF value at Hygroscopic coefficient should be 4.50. For Air dry soil it is 6 (pF) 1000 (atm).
Yupp
Very helpful Sir thank you so much sir
Sir yeh Hygroscopic soil ka jo hai wo 4.5 pf hoga
Sir table 4 plz check it
Ph of saline akline soilis
<,8.5
very important
Informative sir
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