Sustainable rice straw management

Abstract

Labor shortages in the agricultural sector in South and Southeast Asia associated with rapid economic, social, and political changes have led to accelerated mechanization, particularly involving combine harvesters in rice-based cropping systems. Compared to traditional harvesting methods, combine harvesters leave rice straw on the field. The intensification of cropping systems is also resulting in a larger volume of rice straw being produced that, in turn, must be managed over shorter turnaround times between crops. Both of these trends have led to an increase in open-field burning of the straw because it is the easiest option for farmers. While open-field burning can have positive effects on managing pests, it leads to loss of nutrients and creates air pollution that causes human respiratory ailments. In 2018, burning of rice straw and other agricultural residues—which contributes to poor air quality—prompted the Indian government to ban open fires in New Delhi. Burning the straw also removes opportunities for adding value to it. More sustainable rice straw management methods are urgently needed to minimize rice production’s carbon footprint and its negative effects on human health and to maximize adding value to the straw byproduct. Past research on rice straw has focused on isolated topics or component technologies, e.g., to improve straw combustion properties or to analyze nutritional value as an animal feedstock. However, to date, there has been no holistic approach toward rice straw research. Topics that should be considered include (1) the effects of burning straw, (2) incorporation or removal of straw from the field, (3) processing and utilizing straw as different agricultural or industrial byproducts, (4) determining the impact of straw on soil fertility and nutrient cycling, (5) assessing the impact of greenhouse gas (GHG) emissions and environmental pollution on human health, and (6) developing economic valueadding opportunities.