【持続可能性】小規模農家の未来に明るい見通しをもたらす農業介入

The productivity and sustainability of smallholder farms can be enhanced by relatively simple farm management techniques, which have been refined in a ten-year study across millions of farms in China, reports a study published onlinein Nature this week.

The largest challenge for sustainable agriculture occurs in regions in which smallholder farming is predominant. Smallholders number around 2.5 billion worldwide and collectively manage around 60% of all arable land, but their farms are often resource-limited and inefficient. In China, for example, there are 200-300 million households, each farming a few hectares, resulting in excessive resource usage. Nitrogen-based fertilizer applications average around 305 kilograms per hectare each year in China, compared with 74 kilograms worldwide, with over-application causing widespread soil acidification, water pollution and greenhouse gas emissions.

Fusuo Zhang and colleagues present straightforward farming interventions that improve both the productivity and environmental impact of maize, rice and wheat cultivation on smallholder farms in China. The interventions were first refined through over 13,000 field trials, and compared with conventional farming practices. The authors then co-ordinated almost 200,000 other researchers, agricultural technicians and agribusiness personnel to run campaigns, workshops and farm visits to spread their techniques to almost 21 million smallholder farms across China.

Although results varied with crops and climate, average yields increased by more than 10% using the new practices, while fertilizer usage dropped by around 15%. Together, overall profits increased by US$12.2 billion. The interventions also reduced nitrogen pollution by 13.3-21.9% and greenhouse gas emissions by 4.6-13.2%.