Sandy soils are well aerated and free-draining. But that’s about as far as advantages go.
On the downside, they are generally hungry and thirsty as a result of being open and free-draining.
Water is lost rapidly by evaporation from the surface and drainage. And, as the water drains away it takes dissolved plant nutrients with it. Organic matter also degrades rapidly, which compounds the loss of nutrients.
Here are a few pointers to help you make the most of sandy conditions:
Improve the soil
Increasing the soil organic matter is the key to improving sandy soils. If you simply try to add silt or clay, the results are often short lived as most of it will simply flush through the sand.
Increasing organic matter makes the sandy soil ‘sticky’ so water and nutrients are retained for longer. Apply well-rotted, nutrient-rich organic matter, such as well-rotted manure or compost annually.
You could also apply additional plant food in the form of a balanced, preferably slow release fertiliser. Organic matter is most effectively applied as mulch of about five to 10cm in thickness to weeded ground.
It is not necessary to dig organic matter and nutrients deeply into sandy soil as this will only damage the structure you are trying to improve. Leave the transportation to the natural actions of rainfall and beneficial soil organisms that carry nutrients to plant roots where they are needed.
Mulch also reduces evaporation from the soil surface and moderates fluctuations in temperature which may harm plant roots.
Planting an evergreen ground cover also helps particularly in wet seasons when abundant rain increases nutrient leaching.
Pick the right plants
Plants that thrive on sandy soils include many annuals that are either tolerant or adapted to survive in low-nutrient soils. Such plants are often accustomed to drought in their natural habitat.
For example, the foxtail lily naturally grows in dry, stony hills. Its thick, fleshy roots have evolved to conserve the little moisture that is available in such conditions.
Similarly, the sun-loving rock roses naturally dwell in dry, rocky places. As such, their small, tough, often white, hairy leaves conserve vital moisture while deflecting the sun’s burning rays. Many other plants have waxy, bluish foliage which is yet another means by which they conserve precious water.
The beauty of their foliage is often one of their most enduring features and can be used to create exciting mixtures of colours and textures.
In the race to set seed before conditions become too dry, many drought tolerant plants also flower freely and attract pollinating insects with exuberant colours and fragrances.
-The writer is a landscape architect
homeandaway@standardmedia.co.ke
