Gary Vaughan-Smith is no slouch at growing assets. As head of ABN Amro Asset Management’s alternative investment group, he boosted assets from less than $50 million to more than $5 billion in just five years. Now he wants to apply the same skill to growing crops. As a founding partner of London-based SilverStreet Capital, he aims to buy up farms in Africa; raise productivity by using sustainable agriculture, such as no-till farming; and sell the produce domestically. He also wants to teach local farmers better techniques.