Addressing environmental implications of crop stubble burning in Pakistan: innovation platforms as an alternative approach

Comparison of physical and chemical characteristics and oxidative potential of fine particles emitted from rice straw and pine stem burning

Rice straw and stubble burning is widely practiced to clear fields for new crops. However, questions remain about the effects of fire on soil bacterial communities and soil properties in paddy fields. Here, five adjacent farmed fields were investigated in central Thailand to assess changes in soil bacterial communities and soil properties after burning. Samples of soil prior to burning, immediately after burning, and 1 year after burning were obtained from depths of 0 to 5 cm. The results showed that the pH, electrical conductivity, NH4-N, total nitrogen, and soil nutrients (available P, K, Ca, and Mg) significantly increased immediately after burning due to an increased ash content in the soil, whereas NO3-N decreased significantly. However, these values returned to the initial values. Chloroflexi were the dominant bacteria, followed by Actinobacteria and Proteobacteria. At 1 year after burning, Chloroflexi abundance decreased remarkably, whereas Actinobacteria, Proteobacteria, Verrucomicrobia, and Gemmatimonadetes abundances significantly increased. Bacillus, HSB OF53-F07, Conexibacter, and Acidothermus abundances increased immediately after burning, but were lower 1 year after burning. These bacteria may be highly resistant to heat, but grow slowly. Anaeromyxobacter and Candidatus Udaeobacter dominated 1 year after burning, most likely because of their rapid growth and the fact that they occupy areas with increased soil nutrient levels after fires. Amidase, cellulase, and chitinase levels increased with increased organic matter levels, whereas β-glucosidase, chitinase, and urease levels positively correlated with the soil total nitrogen level. Although clay and soil moisture strongly correlated with the soil bacterial community's composition, negative correlations were found for β-glucosidase, chitinase, and urease. In this study, rice straw and standing stubble were burnt under high soil moisture and within a very short time, suggesting that the fire was not severe enough to raise the soil temperature and change the soil microbial community immediately after burning. However, changes in soil properties due to ash significantly increased the diversity indices, which was noticeable 1 year after burning.

Emissions of polychlorinated-p-dibenzo dioxin, dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) from rice straw biomass burning

Atmospheric ultrafine, accumulation mode and coarse fractions collected at representative rice straw open burning areas in Hanoi were investigated to identify characteristics of size distribution and contribution of particles emitted from rice straw (RS) burning season to the atmosphere. The sampling was conducted in two episodes: RS burning episode and RS non-burning episode at Dong Anh and Quoc Oai, in seven consecutive days for each sampling campaign from 2018 to 2019. In the RS burning episode, PM1-2.5 showed the highest fraction among all collected particles in both sampling sites, while PM2.5-10 was the most abundant in RS non-burning season. The average mass concentration of PM2.5 in RS burning period and RS non-burning period were 79.7  46.5 g m-3 and 65.2  21.9 g m-3, respectively at Dong Anh sampling site. Those values were 90.9  33.2 g m-3 in the QO_RS burning site and 71.9  29.3 g m-3 in the TM_RS non-burning site. The proportion of fine particle (PM2.5) at both sites were considerable higher in RS burning period as compared to non-burning period, while the concentration of ultrafineparticle (PM0.1) and coarse particle (PM>10m) were similar between two episodes. This result provides better understanding on size distribution and contribution of fine particles from open RS burning to the atmosphere in Hanoi, which is an useful information for the environmental managers to control RS open burning in Hanoi as well as in Vietnam.

Effects of water and rice straw management practices on water savings and greenhouse gas emissions from a double-rice paddy field in the Central Plain of Thailand

Burning of rice straw is a common practice in northwest India, where rice–wheat cropping system is extensively followed. The practice results in loss of nutrients, atmospheric pollution and emission of greenhouse gases. A field experiment was conducted at Indian Agricultural Research Institute, New Delhi, India during the rabi season (November to April) of 2002–2003 to evaluate the efficacy of the various modes of rice straw recycling in soil in improving yield and soil fertility and reducing not only carbon dioxide emission but also nitrous oxide (N2O) emission. The treatment with no rice straw incorporation and application of recommended doses of fertilizer (120, 26 and 50 kg N, P and K ha−1, respectively), gave the highest yield of wheat. Treatments with the incorporation of rice straw at 5 Mg ha−1 with additional amount of inorganic N (60 kg N ha−1) or inoculation of microbial culture had similar grain yields to that of the treatment with no straw incorporation. The lowest yield was recorded in the plots where rice straw was incorporated in soil without additional inorganic N and with manure application. All the treatments with rice straw incorporation had larger soil organic C despite the effect on the mineralisation of soil organic matter. Emission of N2O was more when additional N was added with rice straw and secondary when straw was added to the soil because of higher microbial activity. The study showed that burning of rice straw could be avoided without affecting yield of wheat crop by incorporating rice straw in soil with an additional dose of inorganic N or microbial inoculation. However, the reduction of N2O emission due to avoiding burning is in part counterbalanced by an increase in emission during the subsequent wheat cultivation.

Energy valorization of rice straw is possible by thermal conversion. The aim of this paper was to study the emissions throughout heating of rice straw under seven different atmospheres (simulating combustion, gasification and pyrolysis). For this purpose, combustion, gasification and pyrolysis of rice straw were studied by simultaneous TG/MS dynamic runs at 15 °C min−1. Results showed that a partially inert atmosphere is more advisable from an environmental point of view due to the lower emission of contaminants.

The Mekong Delta produces 21 Mt of rough rice (Oryza sativa L.) and an estimated 24 Mt of straw (dry weight) annually. Approximately one fourth of the straw is burned on the field, which is a common practice in intensive rice cultivation systems in this region because there is limited time to prepare the field for the next crop. The spread of intensive rice production in the Delta may increase the total biomass of burning crop residues, significantly impacting greenhouse gas (GHG) emissions in Vietnam. In this study, GHG emissions from the major uses of straw (burning and mushroom beds) were monitored in a triple rice cropping system located in the central Mekong Delta. Between September 2011 and November 2012, both wind tunnel and closed chamber methods were used to measure the emissions of major GHGs from straw-burning and straw-mushroom cultivation systems, respectively. The global warming potential (GWP) was then determined. Methane (CH4) and non-methane volatile organic carbon emissions (NMVOC) increased with lower modified combustion efficiency [MCE: emissions ratio of Carbon composing carbon dioxide (CO2-C) and carbon monooxide (CO-C) (CO2-C/(CO-C + CO2-C))]. Furthermore, higher moisture straw stacks generated lower nitrous oxide (N2O) emissions. Small straw stacks (5 or 10 kg dry straw) with higher moisture content emitted more carbon monoxide (CO), CH4 and NMVOC. These results suggest that factors that increase the straw moisture content, such as rainfall, can cause smoldering combustion in small straw stacks or when straw is scattered on the ground, thereby inhibiting N2O emissions but enhancing CO, CH4 and NMVOC. The measured N2O emissions contributed negligible amounts to the GWP compared with measured CO and CH4, which are relatively intense GHG emissions; this was likely a result of the slow and inefficient burning that was observed from the smaller straw stacks with higher moisture content. In this study, rice straw burning threatened to generate more GHGs than straw-mushroom (Volvariella volvacea (Bul. ex Fr.) Singer) cultivation under the studied agroecosystems.

Introducing greenhouse gas mitigation as a development objective in rice-based agriculture: I. Generation of technical coefficients

Kinetic studies on catalytic combustion of rice and wheat straw under air- and oxygen-enriched atmospheres, by using thermogravimetric analysis

The paddy and wheat cropping pattern (PWS) is one of the extensive farming systems in north-western zones of India mainly the river plains of Haryana, Punjab, Rajasthan and western Uttar Pradesh. These river plains famous for extensive agricultural fields are equally defamed for burning of rice and wheat straw and stubbles by peasants after the reaping season. In India, it is reckoned that 22,289 Gg of paddy stubble biomass is generated annually and out of this, 13,915 Gg is blazed in the agricultural fields as calculated. Haryana and Punjab alone produce 48% of the whole straw production which is openly burnt in situ. The flaming of paddy stubbles causes soil nutrient loss of organic carbon (3850 million Kg), nitrogen (59 million Kg), phosphorus (20 million Kg) and potassium (34 million Kg), aside from deteriorating the ambient air quality. Burning of agricultural residue discharges various trace gases like COX, CH4, NOX, SOX and huge quantity of particulates matters (PM10 and PM2.5) which cause adverse impacts on human health. The major problems faced by the local people are eye irritation, dryness of eyes and chest congestion. It also led to chronic obstructive pulmonary disease (COPD), pneumoconiosis, pulmonary tuberculosis, bronchitis, cataract, corneal opacity and blindness. The cases of road accidents also enhance during the period of stubble burning due to poor visibility. It also contributes to haze, greenhouse effect and environmental changes thereto. In India, National Green Tribunal (NGT) prohibited this ancient agricultural practice of straw burning in pollution-wrecked city New Delhi and the adjacent four states viz. Punjab, Haryana, Rajasthan and Uttar Pradesh. One suitable method to reduce this menace is incorporation of straw into soil which eventually enhances soil fertility. The crop residue material can also be used for compost formation as a traditional approach. Alternate energy resources can also be generated from this agro-biomass. The most prominent method to prevent this threat is to generate biomass energy. Further, in past decades, many conversion processes have been developed to produce alternate biofuels under different forms (pellets, briquettes) from crop residues. An integrated crop residue management approach is need of the hour to combat this anthropogenic disaster.

Rice production helps feed at least half of the world’s population but generates approximately one billion tonnes of straw residue per annum. On-site open burning of rice straw after harvesting is common in recent times because there has been less demand for rice straw to use as fuel and fodder. Due to health and climate change concerns, open burning, which results in biomass losses, smog and emissions of green house gases, e.g., CO2, has been widely criticized and banned in many countries. Little is known about the positive benefits of straw burning, such as field care (eradication of biotic diseases) or nutrient cycling. Herein, we propose a new viewpoint in which the burning of rice straw followed by cycling of the burned materials, including silica material (so-called phytolith), into soil is demonstrated as a CO2-sequestration strategy via buffering the soil CO2 flux and coupling CO2 with the silicon cycle.

India is the second-largest producer of rice, which plays an important role in the GDP of the nation, but the burning of rice straw is one of the most severe issues, which the country is facing. The government has tightly regulated this practice, and the farmers are usually advised to incorporate the residue in the soil, but this management option is minimal because of its slow degradation properties in the soil and may also foster rice diseases. A lot of lab-scale and commercial research studies have been conducted on rice straw-based nanocomposites, but rice straw-based bioplastic is a much superior latest technology that is not much explored. Only a few researchers have worked on making biodegradable bioplastic packaging materials from rice straw. The developed technology not only eradicates the pollution problems caused because of stubble burning but also resolves the problem of synthetic plastic packs, which is another major issue worldwide as 40% of the total plastic is used in food packaging. The current study is aimed to explore the feasibility of this agricultural residue to get converted into useful biodegradable packaging materials that can work for agroecological and sustainable development.

India is an emerging economy and has shown a great increase in the production of crops particularly after the green revolution. New kinds of seeds, fertilizers, machinery, and sowing techniques have helped a lot in meeting the needs of the country in terms of grains produced per hectare. Due to the rapid development, there is an increase in the overall pollution giving rise to greenhouse gases, and ultimately depleting the ozone layer along with the rise in the seawater level causing various problems. Air pollution is particularly increasing various respiratory diseases in small children, which is a major concern for society. Rice and wheat are the most popular cultivation in India, which produced stubble. However, wheat stubble can be used as fodder for the cattle, but rice stubble is avoided as it has high silica content. To reduce the ever-increasing pollution, the stubble removing machine (SRM) is designed and developed for fully controlling the pollution due to the burning of paddy stubble. Earlier the only method to clear the agriculture land was to burn the paddy stubble after the harvesting or use machines designed for different applications. Burning of stubble creates a lot of harmful gases like \(CO_{x}\)\(,NO_{x} ,\) and their derivatives. Various other machines were developed including stubble management system (SMS) and its higher version called super SMS but were not so promising according to their application procedure. The present developed machine works on the principle of cutting, collecting, and managing the paddy stubble and clears the fields instantaneously for the next crop and also vanishing the problem of pollution due to the burning of stubble. We propose a system-level solution for the same.

Effect of water and rice straw management practices on yield and water productivity of irrigated lowland rice in the Central Plain of Thailand