Complete Guide to Soil: Types, Nutrients, Crop Suitability

🌍 Understanding Soil – Farming Guide

Soil is the foundation of all agriculture. It determines water availability, nutrient supply, microbial activity, and ultimately the yield and quality of crops. Understanding soil helps farmers choose the right crop, optimize fertilizers, and improve long-term soil health.

🧱 1. What Is Soil?

Soil is a natural mixture of minerals, organic matter, water, air, and microorganisms. It forms through the weathering of rocks over thousands of years and varies widely across regions.

Major Components of Soil

Component	% Composition	Role
Mineral particles (sand, silt, clay)	45%	Structure, water holding, nutrients
Organic matter	5%	Fertility, moisture retention, microbial activity
Water	25%	Dissolves nutrients and supports plant metabolism
Air	25%	Root respiration

🧱 2. Soil Texture & Structure

Soil Texture

Based on particle size:

Sand: Large particles → drains quickly, low nutrients
Silt: Medium particles → good fertility
Clay: Small particles → high water & nutrient holding, poor aeration

Loam Soil

A balanced mixture of sand, silt, and clay.
Ideal for most crops.

🏞️ 3. Types of Soil (Globally & Agriculturally Important)

A. Sandy Soil

Large particles, low water retention
Warms quickly
Low nutrients

Best for:
Groundnut, watermelon, coconut, carrots, potatoes, millets.

B. Clayey Soil

Very small particles
Sticky, poor aeration
High nutrient retention

Best for:
Rice, wheat, sugarcane, jute, cotton.

C. Silt Soil

Fertile and smooth
Good water capacity

Best for:
Vegetables, fruits, tobacco, pulses.

D. Loamy Soil

Balanced texture (ideal structure)
Excellent water retention and drainage

Best for:
Cereals, pulses, oilseeds, vegetables, floriculture, horticulture.

E. Peaty Soil

High organic matter
Acidic
High moisture

Best for:
Vegetables, rice, and crops needing wet conditions.

F. Chalky/Calcareous Soil

High calcium
Alkaline
Low nutrient availability

Best for:
Barley, beets, cabbage, spinach (after amendments).

G. Saline & Alkaline Soil

Excess salts or high pH
Poor growth unless reclaimed

Best for:
Salt-tolerant crops like barley, sugar beet, cotton (with treatment).

H. Black Soil (Regur)

Clayey, rich in iron & magnesium
High swelling-shrinking nature

Best for:
Cotton, soybean, sorghum, maize, groundnut.

I. Red Soil

Sandy to clayey
Rich in iron but poor in nutrients

Best for (with fertilizers):
Millets, pulses, groundnut, potato, tobacco.

J. Laterite Soil

Reddish, acidic, low fertility
Requires organic matter additions

Best for:
Cashew, tea, coffee, rubber.

K. Alluvial Soil

Rich, fertile, well-drained
Found near rivers

Best for:
Rice, wheat, sugarcane, vegetables, fruits.

🧪 4. Soil Nutrients & Their Role in Crop Growth

Primary Nutrients

Nutrient	Role	Deficiency Symptoms
Nitrogen (N)	Leaf & stem growth	Yellowing of leaves
Phosphorus (P)	Root development, flowering	Poor root growth
Potassium (K)	Disease resistance, grain filling	Tip burn, weak plants

Secondary Nutrients

Nutrient	Role	Deficiency
Calcium	Cell walls, root health	Leaves curl
Magnesium	Chlorophyll production	Yellowing between veins
Sulfur	Protein synthesis	Light-green young leaves

Micronutrients

Nutrient	Role	Deficiency
Zinc	Growth hormone regulation	Stunted growth
Iron	Enzyme function	Yellowing in young leaves
Boron	Flower & fruit formation	Cracked stems & fruits
Copper	Photosynthesis	Wilting
Manganese	Metabolism	Interveinal yellowing
Molybdenum	Nitrogen fixation	Yellow, twisted leaves

🌱 5. Soil pH and Its Importance

pH determines nutrient availability.

Soil pH	Category	Suitability
< 5.5	Acidic	Tea, potato, pineapple
5.5–7.5	Neutral	Most crops
> 7.5	Alkaline	Cotton, barley (limited)

🍃 6. Soil Organic Matter (SOM)

Improves:

Water retention
Nutrient availability
Soil structure
Microbial life
Sources:
Farmyard manure
Compost
Cover crops
Green manuring

🚜 7. Crop Suitability Matrix (Soil vs Crops)

Soil Type	Ideal Crops
Sandy	Groundnut, potato, carrot, watermelon
Clayey	Rice, sugarcane, wheat
Loamy	Vegetables, cereals, pulses
Alluvial	Rice, wheat, fruits
Red Soil	Millets, pulses, tobacco
Black Soil	Cotton, soybean, sorghum
Laterite	Tea, coffee, cashew
Peaty	Rice, leafy vegetables
Chalky	Barley, beet

🌍 8. Region-Specific Soils (India, US, Europe, Africa)

🇮🇳 India

Region	Soil Type	Notes
Indo-Gangetic Plains	Alluvial	Highly fertile
Deccan Plateau	Black Soil	Cotton belt
Eastern India	Laterite/Red	Needs fertilization
Western India	Desert/Sandy	Drip irrigation important
Coastal Regions	Saline/Alluvial	Salt-tolerant crops

🇺🇸 United States

Region	Soil Type	Notes
Midwest (Corn Belt)	Mollisols	World’s most fertile soils
Southeast	Ultisols	Acidic; needs lime
Great Plains	Aridisols	Dry; suited for wheat
Northeast	Alfisols	Forest-derived, fertile with amendments
California	Diverse (Entisols, Inceptisols)	High-value crops

🇪🇺 Europe

Region	Soil Type	Notes
Central Europe	Chernozem	Rich in humus; cereals
Mediterranean	Calcareous/Clay	Olives, grapes
Northern Europe	Podzols	Acidic; suited for forestry, potatoes
Eastern Europe	Black Earth	Major wheat-growing region

🌍 Africa

Region	Soil Type	Notes
Nile Valley	Alluvial	Very productive
East Africa Highlands	Volcanic (Andisols)	Coffee, tea
West Africa	Lateritic	Cashew, cocoa
Sahara Belt	Arid, sandy	Drip irrigation needed

🌿 9. How to Improve Soil Health

Physical improvements

Tillage reduction
Adding organic matter
Mulching

Chemical improvements

Liming (to reduce acidity)
Gypsum (to reclaim sodic soils)

Biological improvements

Cover crops
Microbial inoculants
Avoid chemical overuse

Fertigation

Fertigation’ is the technique of supplying dissolved fertiliser to crops through an irrigation system. When combined with an efficient irrigation system both nutrients and water can be manipulated and managed to obtain the maximum possible yield of marketable production from a given quantity of these inputs

Below is the Fertigation Chart (easy to follow, farmer-friendly and technically accurate) followed by a well-written conclusion to complete your soil guide.

💧 Fertigation Chart for General Field Crops

(This chart assumes use of drip irrigation. Adjust quantities based on soil tests and crop specifics.)

1. Fertigation Frequency

Vegetables: 2–3 fertigations/week
Field crops (cotton, maize, soy, cereals): 1–2 fertigations/week
Fruit crops: Weekly, increasing during flowering & fruiting

📘 Standard Fertigation Chart (Example for 1000 m² or 0.1 ha)

(Multiply ×10 for 1 hectare)

A. Basal (Before planting / transplanting)

Stage	Fertigation Material	Quantity	Purpose
Basal preparation	FYM/Compost	500–800 kg	Improves organic matter
	SSP (16% P₂O₅)	20–25 kg	Root establishment
	Gypsum/Lime (if needed)	As per soil test	pH correction

B. Early Growth Stage (1–3 weeks after sowing)

Week	Fertilizer	Dose/1000 m²	Notes
Week 1	Urea	1.5–2 kg	Boosts initial vegetative growth
Week 2	MAP (12:61:0)	1–1.5 kg	Enhances rooting
Week 3	Potassium Nitrate (13:0:45)	1–1.5 kg	Improves vigor; stress tolerance

C. Vegetative Stage (3–6 weeks)

Fertilizer	Dose/1000 m²	Purpose
Urea	2–3 kg/week	Leaf & stemelongation
19:19:19 (NPK)	1–2 kg/week	Balanced nutrition
Calcium Nitrate	1 kg/week	Strengthens cell walls

D. Pre-Flowering Stage

Fertilizer	Dose/1000 m²	Why?
12:32:16	2 kg/week	Pushes flowering
Magnesium Sulfate	0.5–1 kg/week	Prevents yellowing
Micronutrient mix	200–250 g/week	Enhances bud formation

E. Flowering Stage

Fertilizer	Dose/1000 m²	Purpose
13:0:45 (KNO₃)	1.5–2 kg/week	Necessary for flowering & seed set
00:52:34 (MKP)	1–1.5 kg/week	Encourages flower retention
Boron (Soluble)	20–40 g/week	Essential for pollen growth

F. Fruiting / Grain Filling Stage

Fertilizer	Dose/1000 m²	Purpose
Sulfate of Potash (0:0:50)	1.5–2.5 kg/week	Increases size, quality & oil content
Calcium Nitrate	1–1.5 kg/week	Prevents cracking & strengthens fruits

G. Maturity Stage (Last 2–3 weeks)

Fertilizer	Dose	Purpose
Water only / minimum fertigation	—	Helps proper grain hardening & reduces lodging

⭐ Micronutrient Fertigation Guide

(Generalized across major crops)

Micronutrient	Fertigation Dose/1000 m²	Benefits
Zinc (Zn)	50–100 g/month	Prevents stunting
Iron (Fe)	100–150 g/month	Green, strong foliage
Boron (B)	20–40 g/month	Flower & fruit success
Manganese (Mn)	50–80 g/month	Photosynthesis efficiency
Molybdenum (Mo)	5–10 g/month	Nitrogen fixation

🧪 Rules for Safe Fertigation

Always use fully soluble fertilizers.
Maintain pH between 5.5–6.5 in fertigation tank.
Avoid mixing calcium fertilizers with sulfates or phosphates in the same tank.
Filter water to prevent clogging.
Start with water, then feed fertilizer, end with clear water.

🧾 Conclusion

Understanding soil—its texture, nutrients, pH, organic matter, and regional characteristics—is the cornerstone of successful farming. Soil determines not just what can be grown, but also how crops should be fertilized, irrigated, and managed. By choosing the right crops for the right soil, applying nutrients through efficient methods like fertigation, and maintaining soil health through organic matter and proper pH management, farmers can significantly increase yields, improve crop quality, and ensure long-term sustainability.

Healthy soil isn’t just a resource—it is an investment. When farmers nurture soil, the soil returns the favor with better harvests, resilient crops, and a more profitable farm over time.