# Effects of Agricultural Biomass Burning on Regional Haze in China: A Review
## 2 Biomass Burning and Regional Haze
### Solutions for Agricultural Straw  
Although agricultural open field burning was prohibited by the government, the effectiveness of this ban is limited and new solutions should be implemented. Since agricultural straw is very useful, there are some suitable solutions, as follows:  
1. Electricity generation: Electricity generated by biomass generally offers a favorable price, high efficiency and low emissions, but often has unfavorably high land and water usage. Sixty-two countries produce electricity from biomass [42]. In China, the maximum power generation potential of agricultural biomass resources is 70,465.35 MW, and the preferred development areas include Heilongjiang, Henan, Shandong and Jilin provinces [43]. In fact, electricity has been generated in Jilin Provence using this method since 2015.
2. Animal feed supply [44]: Besides cellulose, straw contains hemicellulose and lignin which are palatable to ruminants such as cows.
3. Bio-ethanol production: Rice straw can be used in bio-ethanol production, bringing additional income and allowing sustainable utilization [45].
4. Returning straw to the field: This solution is an important soil management practice to improve soil fertility. For example higher soil organic carbon, nitrogen, and phosphorus contents were observed following straw-returning than under normal tillage.  
These solutions are rarely adopted in China because large volumes of agricultural straw are hard to collect in a short term after harvest, yet timely removal after the harvest is critical to avoiding missing the sowing season. Furthermore, much room is needed for agricultural straw storage before further processing. Therefore, open field burning is widely used as an inexpensive means of disposal in most parts of China.  
Here we propose that prescribed open burning would be a more suitable solution in China. Prescribed burning is the process of planning and applying fire to a predetermined area, under specific environmental conditions, to achieve a desired outcome [46]. It has been used widely in grassland and forest ecosystem as fuel management tool by reducing the intensity, size and damage of wildfire [46]. There are several reasons for this: (1) prescribed burning has been used widely in grassland and forest ecosystem as a fuel management tool by reducing the intensity, size and damage of wildfire [47; 48]; and (2) prescribed burning is an inexpensive and efficient means to clean agricultural straw. However, compared with common open field burning, execution of prescribed burning should consider conditions including wind speed, diffusion of gaseous pollutants and particle matter, air quality, and rainfall forecasts. A lower wind speed would be better than a higher wind speed, to allow control of the area being burned. Atmospheric conditions should be favorable for diffusion, for example before periods of cold air. Prescribed burning should be prohibited during fog or temperature inversion conditions. Background air quality should also be considered. Prescribed burning should be conducted during good or moderate air quality and prohibited during poor or hazardous air quality. Rainfall after the prescribed burning would help reduce particle emissions. Clearly, prescribed burning should be carried out far away from residential areas, shrub land and highways. Heavy smoke from agricultural straw burning should have no effect on highway or airline visibility. Finally, prescribed burning of agricultural straw should be managed by both farmers and governments: farmers carry out the prescribed burning, and the government provides information about when and where agricultural straw should be burned.