admin | March 7, 2016
This week’s story from Zimbabwe talks about drip irrigation. One of the benefits of drip irrigation is that it is one way to avoid the soil salinity that sometimes results from over-irrigation.
Our Script of the week discusses the important issue of how to work with—and avoid—saline soil.
Saline soil is especially common in low-lying areas such as river flood plains, lake beds, and coastal plains. In these places, salty groundwater is often within a few metres of the soil surface.
Most plants either do not grow well in saline soil, or do not grow at all. They become yellowish, wilted, stunted, and usually die.
Saline soil kills plants by interfering with the way they get the water and nutrients they need to grow. Plants take up water and nutrients from the soil by a process called osmosis. In the process of osmosis, a weak solution from the soil moves to a stronger solution in the roots of the plant. That is how plants feed themselves.
In saline soils, the high salt content makes the soil solution more concentrated than the solution in the roots of the plant—the opposite of the usual situation. So instead of nutrients moving from the soil to the plant, they move from the plant to the soil. The process of osmosis works in reverse. Then the plant dies.
This script talks about ways that farmers can overcome the problem of saline soil.