Farm Chemicals Taint Western Cape's Agricultural Rivers

The Western Cape's fertile soil and Mediterranean climate make it an ideal place for farming wheat and grapes, but this comes at a cost. According to plant ecologist Eugene Moll, if plough renosterveld for long enough, its seed bank expires, and the wildflowers, bulbs, and grasses no longer return by themselves.

Agricultural rivers in the region are also contaminated with farm chemicals, which can wash into streams, seep into groundwater, or drift through the air. A 2017-18 drought study found that wheat and grapes face different enemies: wheat farmers relied mainly on weedkillers, while grape growers used more treatments against mildew and other fungal diseases.

The researchers collected spray records from 38 farms and monitored three Western Cape farming areas. They found 53 different chemicals and breakdown products in the rivers, most of which stayed below the warning lines. However, four insect killers crossed those danger lines at least once.

A later study asked where these chemicals were coming from and found a more tangled story. The researchers concluded that 'drivers of pesticide contamination were area dependent' and that each river has its own story.

The studies suggest that farmers may be able to use fewer chemicals without giving up the harvest. A Stellenbosch wheat trial reduced the number of chemical treatments used, but found no negative impact on yields or soil quality.