SciDevNet: Twenty-first century agriculture needs low-input advances like the System of Rice Intensification, says Norman Uphoff. According to the principle of diminishing returns, continuing to produce something in the same way, with the same inputs and technology, usually becomes less productive over time. This appears to apply to agriculture's 'Green Revolution', as yield improvement has slowed in recent decades, no longer lowering the real price of basic foods as it did in its first three decades. Diminishing...