Soil erosion & soy

Soil erosion caused by soybean production is decreasing – a positive step forward. But the current rate of erosion is still unsustainable.

A 1996 study in the United States showed that soil erosion associated primarily with soybean and corn production in the Midwest halved from 37.5 metric tonnes per hectare in 1930 to 19.5 metric tonnes per hectare in 1982 and 15.75 metric tonnes per hectare in 1992. This is happening in other places where soy is grown too.
 Urbanisation and erosion in the Cerrado, Brazil. / ©: WWF-Canon / Mauri RAUTKARI
Urbanisation and erosion in the Cerrado, Brazil.
© WWF-Canon / Mauri RAUTKARI

Highly erodible lands being used

Despite this progress, soil erosion rates are easily still a few times more than is sustainable (defined as a creation of soil greater than or equal to that lost through erosion). And lands classified as "highly erodible" are now being used for soybean production.

In the United States, the Conservation Reserve Program actually paid producers to take highly erodible land out of production. It now appears that the development of herbicide-tolerant ("Roundup-ready") soybeans has encouraged many producers to plant at least some of those lands again.

Genetically modified soybeans

Improved production methods may guard against soil erosion. The soybean varieties genetically modified to tolerate herbicides allow producers to employ no-till and conservation tillage production systems to minimize erosion, even on the most erosion-prone areas. However, the net environmental impact of this change has yet to be determined.

The chief fear with highly erodible lands is that, despite improved techniques, soil erosion will once again become a problem. The Brazilian National Development Bank has warned that "without well defined technical criteria" the soil in many areas of the Amazon could be rendered unusable by soybean cultivation.

Soil compaction

Soybean production also causes soil compaction, damaging the land. In Bolivia, where soybean cultivation has been increasing since the 1970s, degradation is already severe.

Initially, soybeans can be cultivated without fertilizer or lime applications. But soil soon needs these to be able to nourish its crop – and they can damage the environment even further. Eventually, even that’s not enough, and land has to be retired.

In the case of Bolivia, by the late 1990s more than 100,000 hectares of former soybean lands were abandoned to cattle pasture because the soil was exhausted. The settlements that had farmed soybeans had moved further to the north to clear more forests to, once again, plant soybeans.

Credits

Extracts from "World Agriculture & Environment" (2004) by Jason Clay
Soil health can be negatively impacted through repeated application of agrochemicals. Based on soil type and practices, soil erosion and compaction can also become major issues.

Subscribe to our mailing list

* indicates required