Assessment of post-harvest losses and carbon footprint in intensive lowland rice production in Myanmar

Straw application improved soil biological properties and the growth of rice plant under low water irrigation

The application of organic amendments is one way to manage low water irrigation in paddy soils. In this 60-day greenhouse pot experiment involving paddy soil undergoing drying-rewetting cycles, we examined the effects of two organic amendments: azo-compost with a low carbon to phosphorus ratio (C:P) of 40 and rice straw with a high C:P ratio of 202. Both were applied at rates of 1.5% of soil weight (w/w). The investigation focused on changes in certain soil biochemical characteristics related to C and P in the rice rhizosphere, as well as rice plant characteristics. The irrigation regimes applied in this study included constant soil moisture in a waterlogged state (130% water holding capacity (WHC)), mild drying-rewetting (from 130 to 100% WHC), and severe drying-rewetting (from 130 to 70% WHC). The results indicated that the application of amendments was effective in severe drying-rewetting irrigation regimes on soil characteristics. Drying-rewetting decreased soil respiration rate (by 60%), microbial biomass carbon (by 70%), C:P ratio (by 12%), soil organic P (by 16%), shoot P concentration (by 7%), and rice shoot biomass (by 30%). However, organic amendments increased soil respiration rate (by 8 times), soil microbial biomass C (51%), total C (TC) (53%), dissolved organic carbon (3 times), soil available P (AP) (100%), soil organic P (63%), microbial biomass P (4.5 times), and shoot P concentration (21%). The highest significant correlation was observed between dissolved organic carbon and total C (r= 0.89**). Organic amendments also increased P uptake by the rice plant in the order: azo-compost > rice straw > control treatments, respectively, and eliminated the undesirable effect of mild drying-rewetting irrigation regime on rice plant biomass. Overall, using suitable organic amendments proves promising for enhancing soil properties and rice growth under drying-rewetting conditions, highlighting the interdependence of P and C biochemical changes in the rhizosphere during the rice vegetative stage.

Southeast Asia must narrow down the yield gap to continue to be a major rice bowl

Southeast Asia is a major rice-producing region with a high level of internal consumption and accounting for 40% of global rice exports. Limited land resources, climate change and yield stagnation during recent years have once again raised concerns about the capacity of the region to remain as a large net exporter. Here we use a modelling approach to map rice yield gaps and assess production potential and net exports by 2040. We find that the average yield gap represents 48% of the yield potential estimate for the region, but there are substantial differences among countries. Exploitable yield gaps are relatively large in Cambodia, Myanmar, Philippines and Thailand but comparably smaller in Indonesia and Vietnam. Continuation of current yield trends will not allow Indonesia and Philippines to meet their domestic rice demand. In contrast, closing the exploitable yield gap by half would drastically reduce the need for rice imports with an aggregated annual rice surplus of 54 million tons available for export. Our study provides insights for increasing regional production on existing cropland by narrowing existing yield gaps.

Design and assessment of an energy self-supply process producing tetraethyl orthosilicate using rice husk

Combusting rice husk (RH) generates energy and rice husk ash (RHA) containing high amount of silica. Recent studies showed RHA can directly react with ethanol for producing tetraethyl orthosilicate (TEOS), an important substance for different industries. Nevertheless, this process requires an intensive energy supply. This study aims to design and evaluate an energy self-supply process producing TEOS using RH for feasibility. A process simulator was used to design the target process. The simulation results revealed that RH combustion can completely meet the RHA and high energy demands of TEOS production. The economic and environmental benefits were thoroughly evaluated and compared with processes using conventional raw materials (i.e., Si_mg and silica). The evaluation results showed that using RH for TEOS production could reduce CO₂ emissions substantially. Large economic benefit was gained when renewable electricity was co-generated and sold to the power grid as a surplus.

The Losses in the Rice Harvest Process: A Review

We review existing studies on rice harvest loss from the aspects of estimation methods, magnitudes, causes, effects, and interventions. The harvest losses examined occurred from the field reaping to storage processes, including threshing, winnowing, and field transportation. We find that existing studies on rice harvest losses have focused on quantitative losses in Asia and Africa. Lack of knowledge, inadequate harvesting techniques, poor infrastructure, and inefficient harvest management practices are considered critical contributors to the losses. The magnitudes and causes of rice harvest losses are now better understood than interventions, which have simply been presented but lack an assessment of the effects and a cost–benefit analysis. Interestingly, reduction in harvest losses may threaten some farmers’ profits, such as rural women who make their living from post-production manual operations. Considering the current status of the literature, future researchers should examine how to balance social and individual welfare since farmers are key stakeholders in intervention implementation. A good understanding of the existing researches can help clarify future efforts for loss reduction, thereby reducing the burden of increasing agricultural production and promoting sustainable development of resources and the environment.