Soil Testing: When, How and Why

Soil testing is a management practice that farmers need to understand in order to achieve maximum production and consequently maximize profits.

By employing soil testing habits, a farmer will also know the type of plants that are suitable for his farm, the nutrients lacking in his farm and in what quantities.

Soil testing looks into the soil pH which measures the acidity of the soil and how it affects the nutrient availability during plantation. The preferred soil pH for plants is 6.0 – 7.0. However, some acidic plants such as potatoes, radishes and blue berries thrive in soil with pH of 4.5 – 5.5. When soil pH is maintained at the proper level for a given plant, nutrients are at maximum availability.

It is therefore important to consult an expert who will analyze the soil sample and advice on the most suitable crop for planting, based on the soil acidity.

When carrying out a soil test, a farmer is likely to part with approximately Ksh 5,000. The tests samples are taken when wet and may take up to at least seven working days or shorter depending on the condition of the soil sample.

Experts also examine the water used for plant irrigation as it has an impact on the soil. Water with high levels of sodium is considered not suitable.

It is recommended that farmers who practice crop rotation conduct a soil test annually or at least once in every two years. This soil tests aid in determining the amount of fertilizer to be applied on the farm while still protecting the environment from contamination of excess fertilizer runoff.

Farmers whose land need soil correction may take weeks or months to incorporate nutrients such as agricultural lime (calcium, magnesium, potassium) in the soil during land preparation.

Advantages of Soil Testing

1. Improves soil nutritional balance which results to improved yields and economic returns
2. Ensures environmental risk management in terms of excess fertilizer runoff
3. Saves time and money in terms of fertilizer utility and application
4. Protects the crops from insects that can cause damage to the yield