These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass. As the overlying plate lifts up, it also forms mountain ranges. In addition, the diving plate melts and is often spewed out in volcanic eruptions such as those that formed some of the mountains in the Andes of South America.
Yields in Argentina are forecast to be near 120 bushels per acre this season (2013/14) a little above the trend based on the 1999 to 2013 data. Yields in Argentina are pretty erratic, with a record high over 132 bushels per acre in 2009/10 and 93 bushels per acre in 2011/12. For all of the countries and regions included in the analysis the yield variability is the highest in Argentina. The average world corn yield is about 85 bushels per acre. World corn yields are rising at between 1.3 percent and 1.4 percent per year, a faster pace than the growth in world population of 1.16 percent per year. That allows for some modest increase in per capita consumption, even with no increase in corn area.
The trends show that even by 2020, corn yields in Africa will still average below 35 bushels per acre. Even if corn acreage rises by another 5 million acres between now and 2020, imports of about 20 million tonnes will be needed to balance supply with consumption.