Mechanized Collection and Densification of Rice Straw

Abstract

The introduction of combine harvesters has made rice straw collection a major challenge and has brought bottlenecks to the rice straw supply chain. Due to this and the lack of knowledge on the straw’s alternative uses, farmers burn the biomass in the field for ease of land preparation. This practice creates negative impacts on human health and the environment. However, as an alternative to burning, some Asian countries are developing increasing demands for rice straw for mushroom production, cattle feedstock, power generation, and building materials. Mechanized straw collection has become necessary to increase capacity and to lower transportation costs. Baling machines can collect and compact rice straw in varying forms and densities. In the Mekong River Delta of Vietnam, adoption of rice straw balers have significantly improved rice straw management. A baler hauled by a 30-HP tractor has a collection capacity equal to five people, solving the labor shortage problem in rice straw collection. In addition, the volumetric weight of mechanically compacted straw bales is 50-100% higher than that of loose straw, which significantly reduces handling and transportation costs. High-density compaction (e.g., stationary compaction, briquetting, and pelletizing) can further increase the volumetric weight of baled straw from 400% to 700%, reducing transportation costs by more than 60%. Mechanized rice straw collection and densification have contributed to improvement of the supply chain and resulted in sustainable management of rice straw. This chapter discusses the different technologies for rice straw collection, enumerating the benefits and downsides, as well as options for further densification to reduce transportation and handling costs. The benefits and costs of various alternatives for mechanized straw collection and densification are compared and further elaborated.