A maize farmer planting the same seed, using the same fertiliser and rainfall, can still harvest two very different yields simply because of soil type.

Across East Africa, agronomists commonly see maize yields ranging from 2 tonnes per acre on poor sandy or exhausted soils to 5–6 tonnes per acre on fertile loam or volcanic soils under the same management. The difference is not the seed or fertiliser — it is the soil’s ability to hold nutrients, store water and allow roots to grow deeply.

The same effect is seen across many crops:

• Maize: Deep loam or volcanic soils allow strong root growth and water storage, supporting high yields. Heavy clay can hold nutrients well but may waterlog plants if poorly drained.
  
• Kale (sukuma wiki): Produces large leaves on fertile loam or silty soils but struggles in sandy soils that lose nutrients quickly.
  
• Beans: Prefer lighter, well-drained soils such as loam or sandy loam; heavy clay soils often reduce pod formation due to poor root aeration.
  
• Potatoes: Yield best in loose, well-drained soils; heavy clay soils often produce smaller tubers and more disease.
  

However, soil productivity can often be improved quickly. Adding compost or manure, growing cover crops, applying mulch, and breaking compact layers can transform poor soils into productive ones within a few seasons. Organic matter improves structure, allowing soils to hold water and nutrients while remaining easy for roots to penetrate.

Below are the main soil types farmers commonly encounter and how to recognise them in the field.

Clay soil 

How to recognise it

• Sticky when wet and hard when dry
  
• Forms strong clumps that are difficult to break
  
• Can be rolled into a long ribbon when moist

Advantages

• Holds nutrients and water well
  
• Can produce strong maize and cabbage yields when well managed

Challenges

• Poor drainage and slow root growth
  
• Hard to cultivate when wet

How to improve it

• Add compost or manure
  
• Plant deep-rooted crops or cover crops
  
• Improve drainage with raised beds or ridges
  

Loam soil

How to recognise it

• Dark and crumbly
  
• Breaks apart easily in the hand
  
• Holds moisture but is not sticky

Advantages

• Balanced mixture of sand, silt and clay
  
• Excellent water retention and drainage

Best crops

• Maize
  
• Vegetables such as kale
  
• Beans
  
• Potatoes
  

Sandy soil

How to recognise it

• Feels gritty like sand
  
• Cannot form a ball when squeezed
  
• Water drains very quickly

Advantages

• Easy to cultivate
  
• Warms quickly after rain

Challenges

• Fertiliser and water drain away quickly

How to improve it

• Add large amounts of compost or manure
  
• Apply mulch to reduce moisture loss

Silty soil

How to recognise it

• Very smooth or silky, like flour, when rubbed between fingers
  
• Holds moisture well
  
• Forms a weak ball when wet

Advantages

• Often very fertile
  
• Good moisture retention

Challenges

• Can compact easily
  
• May flood in heavy rain

Black Cotton soil

How to recognise it

• Very dark or black colour
  
• Develops deep cracks during dry weather
  
• Extremely sticky when wet

Advantages

• Naturally fertile
  
• Supports good maize yields

Challenges

• Poor drainage
  
• Difficult to cultivate when wet

Management

• Plant on ridges
  
• Add organic matter to improve structure

Red volcanic soil

How to recognise it

• Deep red colour
  
• Loose, well-structured soil
  
• Common in highland farming areas

Advantages

• Among the most productive soils
  
• Excellent for maize, potatoes and vegetables

ManagementMaintain fertility with manure and crop rotation

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