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1. Why indigenous crops matter 2. Soil and plant health 3. Agripreneurship 101 4. The food value chain 5. Regenerative agriculture 6. Indigenous plants in depth 7. Financial literacy 8. Water, weather & climate

Climate skills · Course 8 of 8

Water, weather and climate for farmers

5 modules  ·  75 minutes  ·  All levels  ·  Free

Climate change is not a distant future problem. For farmers in Gauteng, it is already here — in earlier frosts, longer dry spells, more intense storms, and increasingly unpredictable growing conditions. This course teaches you to read weather and climate patterns, manage water intelligently, and build the kind of farming system that becomes more resilient as climate pressure increases — not less.

By the end of this course you will be able to

Understand Gauteng’s rainfall patterns and how they are changing — and what this means for planting decisions
Read a weather forecast and interpret it for farming decisions — irrigation, frost protection, harvesting
Design a farm water system that collects, stores, and uses water efficiently across the growing season
Calculate your farm’s water requirement by crop and season, and match it to your available water supply
Understand the relationship between soil health, organic matter, and water retention — and how improving your soil reduces your water dependency
Module 1 - Gauteng Climate
1
Gauteng's climate — what it is, what it was, what it is becoming
16 min
Every farming decision you make is a climate decision. Understanding Gauteng’s rainfall, frost patterns, and changing weather is essential for successful indigenous crop production.

Gauteng's baseline climate

Gauteng lies on the Highveld (1,500–1,700m above sea level), creating warm summers, cold dry winters, and strongly seasonal rainfall patterns.

Around 70–80% of annual rainfall (600–800mm) falls between October and March, while winters are dry with frequent frost.

The frost risk calendar

Frost timing determines planting and harvesting decisions for all sensitive crops in Gauteng.

October–May is generally frost-free, while May–August carries increasing and then regular frost risk.

How Gauteng's climate is changing

Rainfall is becoming more variable, temperatures are rising, and extreme weather events like hail and drought periods are increasing.

These changes strengthen the case for drought-tolerant indigenous crops such as sorghum, cowpeas, and bambara groundnut.

600mm
Average annual rainfall in Gauteng — almost all concentrated between October and March. This defines every water and planting decision on a farm.

Reading weather forecasts for farming

Use SAWS (weather.gov.za) and agricultural tools to check frost risk, rainfall probability, wind conditions, and temperature trends before every major farming decision.

Reflection

Have you noticed changes in rainfall patterns or frost timing in your area? Check today’s 7-day forecast on weather.gov.za and consider what it means for your farm decisions this week.

Check your understanding

Module 1 · 3 questions · reflection

1. In Gauteng, what percentage of rainfall occurs between October and March?
A) 30–40%
B) 50–60%
C) 70–80%
D) 90–100%
2. Frost risk for sensitive crops in Gauteng typically begins around:
A) March 1
B) May 1
C) June 15
D) August 1
3. Climate change strengthens indigenous farming because:
A) Crops grow faster in all conditions
B) Government subsidies increase
C) Drought-tolerant crops perform better under variable rainfall
D) Frost disappears completely
Module 2 - Water Sources & Rights
2
Water sources, storage, and rights — managing your water supply
16 min
Water is the most constrained resource for most Gauteng smallholder farmers. Managing where it comes from, how you store it, and how you reduce dependency is one of the highest-return resilience strategies in farming.

Your water source options

Municipal water is available but increasingly expensive, typically R8–15 per kilolitre for smallholder agricultural use. Even a small 100m² vegetable system can cost thousands per season in irrigation alone.

Rainwater harvesting is one of the most cost-effective interventions, capturing 12,000–16,000 litres per season from a 20m² roof area.

Rainwater, boreholes, and surface water

Boreholes provide off-grid supply but require high upfront investment (R50,000–120,000). Shared systems are often more realistic.

Surface water access (dams, streams) offers major advantages. Under South African water law, small-scale use for subsistence may not require a full licence.

600–800mm
Gauteng’s annual rainfall, mostly concentrated in summer. Capturing even a fraction of this dramatically reduces irrigation costs.

Water storage systems

The most efficient system is tiered: roof collection into JoJo tanks, followed by gravity-fed drip irrigation. This reduces pumping costs and stabilises supply.

Borehole or dam water can serve as backup systems, while municipal water should be the last resort.

Reflection

What water sources do you currently use, and how much do they cost per month? How quickly could a JoJo tank pay for itself through reduced municipal water use?

Check your understanding

Module 2 · 3 questions · reflection

1. A 20m² tunnel roof in Gauteng typically collects:
A) 2,000–4,000 litres
B) 12,000–16,000 litres
C) 30,000–40,000 litres
D) 50,000+ litres
2. Commercial irrigation from surface water requires:
A) No regulation
B) DWS water use registration or licence depending on scale
C) Only municipal permission
D) Export certification
Module 3 - Irrigation Systems
3
Irrigation systems — matching water delivery to crop needs
16 min
How you apply water is as important as how much you apply. The right irrigation system can reduce water use by 30–50% while improving crop health and reducing disease pressure.

The four irrigation options

Hand watering is best for small beds and seedlings, but becomes inefficient at scale. It is flexible but labour intensive.

Overhead sprinklers are useful for germination but inefficient for established crops and increase disease risk on leafy vegetables.

Drip irrigation delivers water directly to the root zone and is the most practical system for most vegetable production.

Sub-surface drip irrigation is the most water-efficient system, delivering moisture directly below the soil surface with minimal loss.

Water efficiency comparison

Different irrigation systems vary significantly in efficiency depending on evaporation loss, timing, and delivery method.

50–70%
Drip irrigation reduces water loss compared to overhead systems by delivering water directly to the root zone.

Calculating irrigation needs

Summer vegetable beds typically require 25–35mm of water per week. Subtract rainfall to determine irrigation requirements.

This calculation helps size your water storage and plan irrigation scheduling accurately.

Irrigation audit

What irrigation system are you currently using? How much water are you applying per week? What is one change that could immediately reduce water use or improve crop health?

Check your understanding

Module 3 · 3 questions · reflection

1. Drip irrigation reduces evaporation losses by approximately:
A) 10–20%
B) 50–70%
C) 80–90%
D) No difference
2. Overhead irrigation should not be used on established leafy crops because:
A) It is too expensive
B) Wet foliage increases fungal disease risk
C) It damages soil structure
D) It reduces soil nutrients
3. Summer vegetable beds typically require:
A) 5–10mm per week
B) 10–15mm per week
C) 25–35mm per week
D) 60–80mm per week
Module 4 - Soil and Water
4
Soil and water — how building soil reduces your water dependence
14 min
The most powerful long-term water strategy is not storage or irrigation — it is building soil that holds water. Healthy soil reduces irrigation demand dramatically and improves plant resilience.

The physics of water in soil

Sandy soils drain quickly and retain little water, while clay soils hold water tightly but often restrict plant access. Organic matter improves both by balancing structure and water availability.

It increases water-holding capacity in sandy soils and improves drainage and aeration in clay soils.

What organic matter does

Increasing soil organic matter significantly improves water retention, reducing irrigation frequency and cost over time.

8L
Each 1% increase in soil organic matter adds approximately 8 litres of water-holding capacity per m² of soil (to 30cm depth).

From 1% to 5% organic matter

Raising organic matter from 1% to 5% can reduce irrigation frequency from every 2–3 days to every 10–14 days.

This represents a 70–80% reduction in irrigation demand through soil improvement alone.

Mulch as a water-saving tool

Mulching soil reduces evaporation dramatically. A bare soil can lose up to 5mm of water per day, while mulched soil loses less than 0.5mm.

On a 100m² farm, this can save up to 500 litres of water per day.

Reflection

How does seeing composting, mulching, and irrigation as one integrated water system change how you prioritize your farming activities?

Check your understanding

Module 4 · 3 questions · reflection

1. Each 1% increase in soil organic matter adds:
A) 2 litres/m²
B) 5 litres/m²
C) 8 litres/m²
D) 15 litres/m²
2. Increasing organic matter from 1% to 5% reduces irrigation need because:
A) Plants use less water
B) Soil holds significantly more water and stays moist longer
C) Evaporation stops completely
D) Fertilizer increases water retention directly
3. Mulching reduces water loss mainly by:
A) Increasing rainfall
B) Reducing surface evaporation
C) Increasing soil salinity
D) Blocking root growth
Module 5 - Drought & Climate Resilience
5
Drought preparation and extreme weather resilience
13 min
The most resilient farmers are not those who produce the most in good seasons, but those who lose the least in bad ones. Climate resilience is built through preparation, diversity, and systems thinking.

Drought preparation — before it happens

Drought resilience starts in good years. Soil building, water storage, and crop diversification determine how strongly your farm withstands dry periods.

Strong systems reduce risk before climate stress arrives.

Crop diversification as insurance

Different indigenous crops respond differently to water stress. This creates natural resilience across your farm system.

Some crops fail under drought, while others continue producing — ensuring at least partial harvest stability.

Diversity
Sorghum survives drought conditions that kill cowpeas, while bambara groundnut produces when other crops fail.

Emergency water reserve planning

Every farm should calculate minimum water requirements for a 4-week dry period and build storage accordingly.

This ensures survival of high-value crops during unexpected droughts.

Hail and heat resilience

Hailstorms can destroy crops in minutes. Shade netting and tunnels reduce risk significantly.

Heat above 35°C stops crop growth. Indigenous crops like okra and amaranth perform better under these conditions.

Final reflection

What is the single biggest climate risk your farm faces today — drought, heat, hail, or water shortage? What one change would reduce that risk immediately?

Check your understanding

Module 5 · Final questions

1. Crop diversification helps against drought because:
A) All crops share water equally
B) Different crops fail at different stress levels, ensuring some survival
C) It increases rainfall
D) It eliminates water need
2. At temperatures above 35°C most crops:
A) Grow faster
B) Stop growing and show heat stress
C) Improve yield
D) Require no water