Half-feed combine harvesters: a quantification of their grain savings and carbon reductions with selected hybrid rice varieties

Many of the modern hybrid rice varieties have shatter resistance bred into them. This trait can ironically lead to harvest losses in the field if combine harvesters lack threshing power to remove them. Full-feed combine harvesters, that are common around Asia, can encounter such problems due to the grains holding fast to the panicle and passing through the combine to fall back into the field. These losses can outweigh the additional yields from growing hybrids. If these grain losses could be avoided, it would not only go straight to farmers' bottom lines and increase their net incomes; it would require fewer rice fields to produce the same output, saving greenhouse gas emissions. In this study in the Philippines, half-feed combine harvesters have been shown to avoid significant grain losses from shatter-resistant hybrid rice. Field experiments were conducted on different hybrids, accounting for the harvest times and field conditions, to give an overview of the savings that can be made in both grain and greenhouse gas emissions. Findings are presented here, along with policy recommendations.