Cost of Rice Straw Management
Attributes
Medium: Animals, Plants and/or Others
Country: Philippines
Analytical Framework(s): Economic Analysis
Study Date: 2010
Publication Date: 2013
Major Result(s)
| Resource/Environmental Good | PHP, per ha per year (2010) |
PHP, per ha per year (2014)1 |
USD, per ha per year (2014)2 |
|---|---|---|---|
| total cost of late stubble incorporation and straw burning (baseline) | 3,230.00 | 3,764.63 | 84.17 |
| total cost of late stubble and straw incorporation | 1,104.00 | 1,286.73 | 28.77 |
| total cost of late stubble incorporation and straw removal for use as animal feed | 4,550.00 | 5,303.12 | 118.57 |
| total cost of early stubble and straw incorporation | 1,104.00 | 1,286.73 | 28.77 |
| total cost of late stubble incorporation and straw compost incorporation | 4,863.00 | 5,667.92 | 126.73 |
| total cost of early stubble incorporation and straw compost incorporation | 4,863.00 | 5,667.92 | 126.73 |
| total cost of stubble and straw composting and straw compost incorporation | 17,842.00 | 20,795.21 | 464.95 |
About the Inflation Adjustment: Prices in Philippines (PHP) changed by 16.55% from 2010 to 2014 (aggregated from annual CPI data), so the study values were multiplied by 1.17 to express them in 2014 prices. The study values could be expressed in any desired year (for example, to 2025) by following the same inflation calculation and being sensitive to directional (forward/backward) aggregations using your own CPI/inflation data.
Study Note: While some evidence points to the negative health impacts of rice straw burning and the positive sustainability impacts of other rice straw management options, these benefits are difficult to value and incorporate in the economic analysis at this point. Thus, the economic analysis in this study is limited to considering the GHG emissions given the rice straw management alternatives. Also, while the study reports some literature on the potential use of rice straw for biofuel and power generation, it focuses more on evaluating farmers' applicable alternatives.
Study Details
Summary: This research project was generally aimed at assessing the environmental consequences of rice straw burning and other straw management practices and evaluating the cost-effectiveness and adoption of selected rice straw management alternatives. Based on the emissions inventory considering the incremental GHG emissions from rice straw management practices, the estimated contribution of rice residues is around 16 M tons of CO2-eq considering only CH4 and N2O emissions. This is approximately 8% of the total projected CO2-eqemissions for 2008 based on the Philippines' first initial national communication on climate change. The current practice of incorporating rice straw stubble into soil during land preparation in wet or flooded conditions less than a month before transplanting is the largest contributory rice residue management practice on a per year basis not considering potential long-term impacts. On a per hectare basis calculated for a five-year period based on IPCC 2006 Guidelines, compiled factors from literature and various assumptions, the total estimated emission level, considering only CH4 and N2O gases, is around 51 tons CO2-eq for the baseline scenario. Economic analysis from the point of view of rice farmers indicated that merely shifting from incorporating stubble before transplanting and straw burning to incorporating both stubble and straw in the soil over 30 days before crop establishment appears to be the most cost-effective option with a negative abatement cost (benefit) of Php 21 (US$ 0.50) per ton CO2-eq reduction. Incorporating both rice stubble and straw less than a month before cultivation, on the other hand, appears to result in a slight net increase in emissions. On the determinants of rice straw management practice or why farmers choose to burn, incorporate, or remove rice straw, a mix of socio-economic, farm, and awareness and attitude variables are prominent.
Site Characteristics: The practice of rice straw open-field burning is a major source of air pollutants such as carbon dioxide (CO2), carbon monoxide (CO), un-burnt carbon as well as traces of methane (CH4), nitrogen oxide (N2O) and comparatively less amount of sulphur dioxide (SO2). The term "straw" often includes both the rice stubble left in the paddy field after harvesting and the rice straw by-product after threshing. In this report, stubble is used to refer to the lower part of the rice plant left in the field after harvesting, and rice straw to refer to loose straw output after threshing. Rice straw burning is also known to emit particulate matters and other elements such as dioxins and furans that impact human health. Burning of rice straw and other agricultural waste contribute more dioxins and furans to air and land than vehicle emissions. Studies also show that rice straw burning causes loss of major nutrients in the soil: almost complete nitrogen (N) loss, phosphorous (P) losses of about 25%, potassium (K) losses of 20%, and sulphur (S) losses of 5 to 60%. Given these negative effects of open-field rice straw burning on the environment and human health as documented in Philippine and international literature, farmers have been encouraged to refrain from burning rice straw, and adopt more environment- and human-friendly rice straw management practices. In fact, both the existing solid waste management law in the Philippines (RA 9003) and the Philippine Clean Air Act of 1999 prohibit in principle open-field burning which includes burning of rice straw. Ordinances specific against rice straw burning have also been passed in some provinces and towns.
Comments: The authors noted that there is evident uncertainty about the rate of growth of emissions, their general effects, and their local effects. They said that the results of this study, particularly on GHG emissions, are only indicative and the cost-effectiveness analysis must be interpreted in relative terms. For rice-based farmers, they mentioned that there are other mitigation options such as water management and tillage options. According to the authors, since affordability of technologies is a prime issue in the mitigation of GHG emissions, further study of the economics of these other mitigation options relative and complementary to rice straw management practices would provide broader information useful for farmers, policy-makers, and other rice stakeholders.