Creating productive atoll soils

Dear Editor,

Please give your consideration to this letter.

Yours sincerely,

Frank Short

Many of Solomon Islands atolls are suffering more and more from sea rise occasioned by climate change and I believe people living on such atolls are increasingly finding it difficult to grow sufficient food due to the poor quality of the soil.

I decided to see what could find online that might offer a solution to the poor soil quality, and I quote what I read in a paper released by the University of Tasmania

The main problem is that atoll soils are formed almost entirely from coral (calcium carbonate with some magnesium). They are sandy with no clay, so water runs straight through them.

The soil is often salty, highly alkaline and low in nutrients, such as potassium, iron and manganese, which are needed by plants. Atoll crops, then, need to tolerate drought, salt and alkalinity.

Inorganic fertilizers and chemical pesticides are banned on some atolls as they could pollute underground water. Traditionally, soil fertility for growing crops, such as swamp taro, has been improved by adding compost. Apart from providing the necessary nutrients, this buffers against drought, salinity and high soil pH.

But rather than just making compost with whatever material is available, we decided to take a more scientific and targeted approach. We’re evaluating the nutrient content of leaves from atoll plant species and other materials, such as ash from cooking fires and fish by-products, to find the best mix.

Nutrient deficiencies can be determined from a soil test and to fix these, suitable leaves and other materials are added to the compost. To correct for low levels of iron in the soil, for example, supplements of ash, lagoon algae and plants that accumulate iron, such as beach cowpea and chaya, can be included in the compost mix.

Potassium is generally required by plants in large amounts. Fortunately, ash contains high levels of potassium, as do coconut shells and husks, which are commonly used in cooking fires. Another excellent source of potassium is the seaweed genus Kappaphycus.

Improving soil health and growing and eating nutritious crops on these isolated atolls will lead to improved diet, nutrition and health. Our approach can also increase rural employment and income and the resilience of atoll food systems to climate change. And all of this will help strengthen nutrition security on atolls and help to prevent non-communicable diseases such as diabetes.

End of quote.

I hope this brief piece might prove helpful.

Yours sincerely

Frank Short


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