Straw pellets are widely promoted and expected to be a cleaner alternative fuel to unprocessed crop residues and rawcoal in rural China.However,the effectiveness of these dissemination programs is not well evaluated.I...Straw pellets are widely promoted and expected to be a cleaner alternative fuel to unprocessed crop residues and rawcoal in rural China.However,the effectiveness of these dissemination programs is not well evaluated.In this field study,emission characteristics of burning strawpellets,rawcoal,and unprocessed corn cobs in heating stoveswere investigated in a pilot village in Northeast China.Emission measurements covering the whole combustion cycle(ignition,flaming,and smoldering phases)shows the promotion of improved heating stoves and straw pellets could reduce pollutant emissions(e.g.,SO_(2) and CO),but increase NO_(X) and PM_(2.5) emissions compared to the initial stove-fuel use pattern in the studied area.There is a significant variance in emission characteristics between different combustion phases.The normalized emission concentrations of the different stove-fuel combinations were higher than the limits in the Chinese national standard for heating stoves,indicating that the standard is not met for real-world emissions.Coal consumption was lower than official data.Household surveys were conducted to identify the barriers to fuel and stove access associated with existing promotion strategies,management,and policies.The pilot program was of the typical“subsidy-and-policy-dependence”pattern and was unlikely to be implemented on a large scale.Technological innovation,operational optimization,and proper policies considering the local socioeconomic factors are needed to sustain the promotion of biomass straw pellets and stoves.展开更多
Salt stress can be alleviated by straw layer burial in the soil, but little is known of the appropriate form of the straw layer for optimal regulation of soil water and salinity because of the uncontrollability of fie...Salt stress can be alleviated by straw layer burial in the soil, but little is known of the appropriate form of the straw layer for optimal regulation of soil water and salinity because of the uncontrollability of field tests. Here, the following four straw forms with compaction thickness of 5 cm buried 40–45 deep were studied: no straw layer(CK), segmented straw(SL, 5 cm in length), straw pellet(SK), and straw powder(SF). The three straw forms(SL, SK and SF) significantly delayed the infiltration of irrigation water down the column profile by 71.20–134.3 h relative to CK and the migration velocity of the wetting front under SF was the slowest. It took longer for the wetting front to transcend SK than SL but shorter for it to reach the bottom of soil column after water crossed the straw layer. Compared with CK, the average volumetric water content in the 0–40 cm soil layer increased by 6.45% under SL, 1.77% under SK and 5.39% under SF. The desalination rates at the 0–40 and 0–100 cm soil layers increased by 5.85 and 3.76% under SL, 6.64 and 1.47% under SK and 5.97 and 4.82% under SF. However, there was no significant difference among straw forms in the 0–40 cm soil layer. Furthermore, the salt leaching efficiency(SLE, g mm^–1 h^–1) above the 40 cm layer under SL was 0.0097, being significantly higher than that under SF(0.0071) by 37.23%. Salt storage under SL, SK and SF in the 40–45 cm layer accounted for 4.50, 16.92 and 7.43% of total storage in the 1-m column profile. Cumulative evaporation under SL and SF decreased significantly by 41.20 and 49.00%, with both treatments having the most significant inhibition of salt accumulation(resalinization rate being 36.06 and 47.15% lower than CK) in the 0–40 cm soil layer. In conclusion, the different forms of straw layers have desalting effects under high irrigation level(446 mm). In particular, SL and SF performed better than SK in promoting deep salt leaching and inhibiting salt accumulation on the soil surface. However, SL was simpler to implement and its SLE was higher. Therefore, the segmented 5 cm straw can be recommended as an optimum physical form for establishing a straw layer for managing saline soils for crop production.展开更多
基金supported by the Ministry of Science and Technology of China(No.2017YFC0211400)and the China Office of Clean Air Asia.
文摘Straw pellets are widely promoted and expected to be a cleaner alternative fuel to unprocessed crop residues and rawcoal in rural China.However,the effectiveness of these dissemination programs is not well evaluated.In this field study,emission characteristics of burning strawpellets,rawcoal,and unprocessed corn cobs in heating stoveswere investigated in a pilot village in Northeast China.Emission measurements covering the whole combustion cycle(ignition,flaming,and smoldering phases)shows the promotion of improved heating stoves and straw pellets could reduce pollutant emissions(e.g.,SO_(2) and CO),but increase NO_(X) and PM_(2.5) emissions compared to the initial stove-fuel use pattern in the studied area.There is a significant variance in emission characteristics between different combustion phases.The normalized emission concentrations of the different stove-fuel combinations were higher than the limits in the Chinese national standard for heating stoves,indicating that the standard is not met for real-world emissions.Coal consumption was lower than official data.Household surveys were conducted to identify the barriers to fuel and stove access associated with existing promotion strategies,management,and policies.The pilot program was of the typical“subsidy-and-policy-dependence”pattern and was unlikely to be implemented on a large scale.Technological innovation,operational optimization,and proper policies considering the local socioeconomic factors are needed to sustain the promotion of biomass straw pellets and stoves.
基金funded by the National Natural Science Foundation of China (31471455 and 31871584)the National Key Research and Development Program of China (2016YFC0501302)
文摘Salt stress can be alleviated by straw layer burial in the soil, but little is known of the appropriate form of the straw layer for optimal regulation of soil water and salinity because of the uncontrollability of field tests. Here, the following four straw forms with compaction thickness of 5 cm buried 40–45 deep were studied: no straw layer(CK), segmented straw(SL, 5 cm in length), straw pellet(SK), and straw powder(SF). The three straw forms(SL, SK and SF) significantly delayed the infiltration of irrigation water down the column profile by 71.20–134.3 h relative to CK and the migration velocity of the wetting front under SF was the slowest. It took longer for the wetting front to transcend SK than SL but shorter for it to reach the bottom of soil column after water crossed the straw layer. Compared with CK, the average volumetric water content in the 0–40 cm soil layer increased by 6.45% under SL, 1.77% under SK and 5.39% under SF. The desalination rates at the 0–40 and 0–100 cm soil layers increased by 5.85 and 3.76% under SL, 6.64 and 1.47% under SK and 5.97 and 4.82% under SF. However, there was no significant difference among straw forms in the 0–40 cm soil layer. Furthermore, the salt leaching efficiency(SLE, g mm^–1 h^–1) above the 40 cm layer under SL was 0.0097, being significantly higher than that under SF(0.0071) by 37.23%. Salt storage under SL, SK and SF in the 40–45 cm layer accounted for 4.50, 16.92 and 7.43% of total storage in the 1-m column profile. Cumulative evaporation under SL and SF decreased significantly by 41.20 and 49.00%, with both treatments having the most significant inhibition of salt accumulation(resalinization rate being 36.06 and 47.15% lower than CK) in the 0–40 cm soil layer. In conclusion, the different forms of straw layers have desalting effects under high irrigation level(446 mm). In particular, SL and SF performed better than SK in promoting deep salt leaching and inhibiting salt accumulation on the soil surface. However, SL was simpler to implement and its SLE was higher. Therefore, the segmented 5 cm straw can be recommended as an optimum physical form for establishing a straw layer for managing saline soils for crop production.
