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The input of organic substances (e.g., rice straw) in rice field soils usually stimulates the production and emission of the greenhouse gas methane (CH4). However, the amount of CH4 derived from the applied rice straw, as well as the response of bacterial and archaeal communities during the methanogenic phase, are poorly understood for different rice field soils. In this study, samples of five different rice soils were amended with 13C-labeled rice straw (RS) under methanogenic conditions. Immediately after RS addition, the RS-derived CH4 production rates were higher in soils (Uruguay, Fuyang) that possessed a stronger inherent CH4 production potential compared with other soils with lower inherent potentials (Changsha, the Philippines, Vercelli). However, soils with higher inherent potential did not necessarily produce higher amounts of CH4 from the RS applied, or vice versa. Quantitative PCR showed copy numbers of both bacteria and methanogens increased in straw-amended soils. High-throughput sequencing of 16S rRNA genes showed distinct bacterial communities among the unamended soil samples, which also changed differently in response to RS addition. Nevertheless, RS addition generally resulted in all the rice field soils in a relative increase of primary fermenters belonging to Anaerolineaceae and Ruminococcaceae. Meanwhile, RS addition also generally resulted in a relative increase of Methanosarcinaceae and/or Methanocellaceae. Our results suggest that after RS addition the total amounts of RS-derived CH4 are distinct in different rice field soils under methanogenic conditions. Meanwhile, there are potential core bacterial populations that are often involved in primary fermentation of RS under methanogenic conditions. [ABSTRACT FROM AUTHOR]

Rice, as a main crop, contributes to food security in Asia. However, its by-product, rice straw, poses challenges as it is often disposed of unsustainably. This research investigates the environmental performance of a 1000 m3 rice straw biogas pilot plant in Laguna, Philippines. A lifecycle assessment identified the climate change impact of the biogas system, straw burning and soil incorporation. In addition to GWP100, the global temperature potential's dynamic climate effects were assessed, including integrated radiative forcing and instantaneous temperature effects. The timeframe of the biogenic emission fluxes of rice production is particularly relevant as the sequestered CO 2 during plant growth is partly released as methane and CO 2 , depending on the straw management practices. Straw burning had the highest net emission impact. However, straw incorporation has the highest short-term radiative forcing and temperature increase. The biogas system provided significant short- and long-term GHG emission reduction of up to 68 % when biogas replaced burning or soil incorporation and the use of fossil fuels. Still, considerable uncertainties remain about fugitive methane emissions, handling and post-processing of the digestate. While single GHG emission figures on a GWP100 basis are useful for informing decision-making, this single-metric approach limits understanding of rice production's short- and long-term impacts. Additionally, our assessment emphasises the necessity for governance frameworks that promote sustainable practices in rice farming, as banning rice straw burning may result in less favourable outcomes from soil incorporation, whereas integrating biogas offers a solution benefiting rice-growing communities and global sustainability efforts. • Biogas from rice straw reduces emissions by up to 69 %. • Soil incorporation of straw has highest short-term (20 years) temperature increase. • Assessing more than one metric and timeframe supports more informed decision-making. • Governance frameworks enabling bioenergy integration support SDG 3, 7 and 13. [ABSTRACT FROM AUTHOR]

In the Philippines, biomass-fueled cogeneration plants use sugarcane bagasse, rice husk, or a mix of agricultural residues as feedstock. Burning these residues results in the continuous generation of ash, accumulating over time and needing appropriate disposal. As a preliminary, the annual potential amount of rice husk and rice straw generation, the available energy that could be recovered, and potential ash generation in the Philippines were estimated in this study. More specifically, the contribution of generated ashes toward reducing greenhouse gas (GHG) emissions when used to displace part of the required cement in cement-based industries was assessed and evaluated. Residues from paddy rice could provide up to ∼10,444 GWh of electrical energy when used as fuel. Utilization of the generated fly ashes (∼634 kt rice straw fly ash and ∼267 kt rice husk fly ash) alone could, on average, reduce ∼681 kt CO 2_eq annually. The transportation of the ashes before their utilization entails significant GHG emissions. However, transporting the ash within the critical distance of 2,995 km would ensure a positive net reduction. In addition, the handling and transportation cost of coal, rice, and sugarcane ashes within the archipelago was also evaluated and compared. The resulting costs (0.94–6.8 USD/40-kg bag) of different ashes are competitive with the current cement retail price (4.00–7.45 USD/40-kg bag). Potential applications, impacts, limitations, and foreseen challenges in using rice residue ashes are also discussed. • Rice residues (RR) generated in the Philippines are estimated to be ∼6.3 Mt/year. • The utilization of RR in power generation plants can displace 18% of coal. • The potential amount of fly ash (FA) from RR ranges from 1,001 to 2,125 kt/yr. • Fly ash from RR as cement replacement will reduce GHG emissions (681 kt CO 2_eq /yr). • The cost of transporting FA is competitive with cement at 20 to 170 USD per ton. [ABSTRACT FROM AUTHOR]

This study applied a multinomial logit model to understand why farmers choose to burn, incorporate or remove rice straw in the field. Four hundred randomly selected farmers were interviewed in four major rice-producing provinces covering the 2009 wet and 2010 dry seasons. Results of the model with burning as the baseline category indicate farm type, location dummies, number of household members with older than 13 years, cow ownership and distance from farm to house as significant variables influencing farmers’ choice of straw incorporation or removal over burning. Significant perception variables are the negative impacts of open-field burning, awareness of environmental regulations and attitude towards incentives. Other factors significantly influencing the decision to incorporate over-burn are training attendance and perceptions of effects of straw incorporation. Income from non-rice farming, total area cultivated, tenure status, presence of burning and solid waste management provincial ordinances are significant factors affecting choice to remove over burn. Continually providing farmers’ training in rice production, increasing demand for rice straw for other uses, and increasing awareness of environmental laws and regulations are policy directions recommended. [ABSTRACT FROM AUTHOR]

Rice is a widely grown crop in Asia. China (30%) and India (21%) contribute to about half of the world''s total rice production. In this study, three major rice-producing countries in Asia are considered, India, Thailand and the Philippines (the later two contributing 4% and 2% of the world''s rice production). Rice straw is one of the main field based residues produced along with this commodity and its applications vary widely in the region. Although rice production practises vary from one country to another, open burning of straw is a common practice in these countries. In this study, an approach was followed aiming at (a) determining the quantity of rice straw being subject to open field burning in those countries, (b) congregating pollutant specific emissions factors for rice straw burning, and (c) quantifying the resulting air pollutant emissions. Uncertainties in the results obtained as compared to a global approach are also discussed. [Copyright &y& Elsevier]

We developed an inflatable solar dryer for mushroom drying, which was adapted from the Solar Bubble DryerTM originally designed for paddy drying. The improved dryer with an added perforated elevated floor ensured the quality without any requirement of mixing or turning of the mushrooms during drying. Its drying performance and economic feasibility were evaluated through determination of the drying parameters including moisture content (MC) reduction, mushroom quality, energy efficiency, greenhouse gas emissions, and cost-benefits ratio. Mushroom MC was reduced from 90% down to 40–60% within 2–4 h, corresponding to the drying rate at this stage of 10–20% h−1. At the next stage, it took about 4–6 h corresponding to a drying rate of 2–10% h−1 to reach the required product MC of 8–10%. The color of the dried mushrooms still remained white-cream. The drying process required 4.57 MJ, emitted 0.33 kg CO2e, and required an input cost of 1.86 $US kg of dry product. For the specific case in the Philippines, this can generate a net profit of 468–1468 $US−1 year−1 and the investment will break even in 1.3–4.0 years corresponding to the selling price of dry mushroom of 10–12 $US kg−1. The study developed a solution to improve the solar bubble dryer and verified its drying process for mushroom drying at farm scale. It would add a significant value to farmers' income as well as a diversified source of nutrient-rich food. [ABSTRACT FROM AUTHOR]

Rice is the main agricultural crop in the Philippines and central to the country's food security. One main challenge of rice farming is the management of the straw after harvest. With limited uses, the rice straw is currently burned or in some cases incorporated with significant environmental impacts. However, it can be an important feedstock for sustainable bioenergy and support energy access in the Philippines. The research was conducted around a 1000 m3 biogas pilot plant in Laguna province, Philippines. The aim of this research was to develop business models and assess their potential for improving energy access, agricultural practices, and empowering local rice-growing communities. Four business models were developed, reflecting energy supply and demand approaches. This was informed by interviews with stakeholders, including farmers, agricultural entrepreneurs, local authorities, and policymakers in the case study location. A multi-criteria assessment was conducted to evaluate synergies and trade-offs between different aspects of the business models. While all business models provided positive environmental, economic, and in particular social sustainability impacts, the farming community showed the most support for approaches that provide wider livelihood benefits beyond renewable energy access, such as diversification of agricultural activities and income generation. This demonstrated that bioenergy has the potential to create a virtuous circle of benefits for local communities in support of sustainable development. To achieve this, it is essential to take a holistic and multi-level approach to the different sustainability criteria to maximise benefits and mitigate negative impacts of bioenergy systems beyond energy technology. • Sustainability trade-offs of different business models for biogas from rice straw in the Philippines were investigated Figure 1. • Four business models for a 1000 m3 biogas pilot plant for rice straw where developed. • Business models with wider livelihood benefits beyond energy access had most support from farmers. • A narrow focus on energy access is unlikely to enable system integration and benefits. • Recognising support for wider livelihood activities supports energy access and vice versa. [ABSTRACT FROM AUTHOR]

Rice plants are Si accumulators and the uptake of Si can significantly improve their growth and stress tolerance. The Si that is taken up polymerises in above-ground plant tissues and forms amorphous silicon bodies called phytoliths. When rice straw is left on rice fields this biogenic Si pool may be an important source of plant-available Si, especially in old, highly weathered soils. Reports on the bioavailability of phytoliths are, however, sparse and sometimes contradictory. To study the in-situ dissolution of phytoliths over time in the field requires the extraction of phytoliths from rice straw. Several different extraction methods have been proposed but their impact on the morphology and surface chemistry (and consequently the solubility) of the phytoliths is not well studied. We have tested four different extraction methods: (i) oxidation with H2O2, (ii) wet ashing, (iii) dry ashing, and (iv) microwave treatment to extract phytoliths from Si-rich rice straw (Oryza sativa L. cv. NSIC Rc222) from the Philippines. The effect of the extraction methods on the morphology of the phytoliths was analysed using confocal laser scanning microscopy, while changes in particle size and specific surface area were determined by dynamic light scattering and N2 gas adsorption at 77 K, respectively. Surface chemistry was analysed with X-ray photoelectron spectroscopy (XPS); bulk element composition was determined using inductive-coupled plasma‒optical emmission spectrometry after microwave digestion. Dissolution experiments in mini reactors were carried out for assessing the solubility of phytoliths under conditions similar to those in the field. Data analysis is currently underway. First results using XPS suggest that dry ashing resulted in very clean SiO2 surfaces suitable for tracking of surface transformations of phytoliths in soil. [ABSTRACT FROM AUTHOR]

Research on the ecology and biogeochemistry of silicon (Si) in paddy rice ecosystems is motivated by the importance of Si as a beneficial plant nutrient, its role in pedogenesis, and the tight links between the cycles of Si and those of other important nutrients and toxic elements. The talk firstly will compile recent progress in understanding about the ecological functions of Si in rice ecosystems, including its role in improving the resilience of rice plants against a wide variety of stresses and in recycling of nutrients via rice straw decomposition. Secondly, knowledge about the multiple operating controls on Si cycling and availability is summed up. These include 'natural' site conditions such as parent material, soil weathering status and climate as well as agricultural practices including irrigation and rice straw export from the fields. Here, the focus is on own results obtained during research on sustainable rice production in Vietnam and the Philippines within the interdisciplinary LEGATO project. Several authors pointed out the potential importance of Si management as crucial factor for more sustainable rice production systems. For instance, better utilization of the benefits Si provides to rice plants, such as resistance against pests, may help to design production systems with reduced input of harmful pesticides. The talk will ponder on these ideas and on the knowledge gaps that currently limit the ability to efficiently manage Si balances and availability in rice ecosystems. [ABSTRACT FROM AUTHOR]

In this study, new methods to improve the mass production of the Philippines fruit fly Bactrocera philippinensis Drew & Hancock were assessed. A new adult screen cage equipped with perforated egging tubes was designed. The replacement of sweet potato with sugarcane bagasse, rice straw or powdered corn as an alternative bulking agent in the standard artificial larval diet was found to lead to positive results in large-scale rearing. Rearing protocols and product quality control procedures for egg incubation, sieving of pupae and pupal holding were examined. The adoption of these new rearing procedures at low cost was found to increase the production of the Philippines fruit fly in a mass-rearing facility without reducing the fitness of the insect. [ABSTRACT FROM PUBLISHER]