Soil erosion & soy
Highly erodible lands being usedDespite 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 has 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 soybeansImproved 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 compactionSoybean 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.