Review on China's wind power policy (1986-2017).

As an important renewable energy source, wind power plays a key role in mitigating climate change and has become one of the fastest growing clean energies globally. In China, wind energy development has been a vital component of national energy transformation strategy. Over the years, the Chinese government has introduced a series of policies to promote the development of wind power and also to regulate this emerging industry. Base on examining all the key policy documents on wind power issued by the Chinese government over the last 30 years, we find that China has built up a comprehensive policy system, and summarized the current framework of Chinese wind power policy systematically. Then, we analyze the policy objectives, policy tools, major measures, their results in each development stage, and the characteristics and trends of China's wind power policies. Finally, we discuss the limitations of the current policy and put forward corresponding suggestions.

Impact of straw management on seasonal soil carbon dioxide emissions, soil water content, and temperature in a semi-arid region of China.

The use of crop residues as mulching materials or organic fertilizer, instead of burning, can help improve the soil organic carbon (SOC) and crop grain yield. An experiment was conducted for three consecutive seasons from 2013 to 2016, to study the effect of no straw (S0), S1/2 (700 kg/ha soybean straw, and 3000 kg/ha wheat straw), and S1 (1400 kg ha-1 soybean straw, and 6000 kg/ha wheat straw) treatments in wheat-soybean multi-crop system. The randomized complete block design was used with three repeats. Compared with the S0 regime, a significant increase of 0.5%-8.7% and 1.4%-27.7% in soil CO2 emission was observed in the S1 regime during all growth stages of summer soybean and winter wheat, respectively. Soil temperature of S1/2 and S1 was 0.1-1.1 °C and 0.3-1.4 °C higher than that of S0 during the seeding stage and greening stage for wheat, during 2013 to 2016. During wheat season, soil moisture was higher in the S1 than in the S0 treatment. Likewise, wheat, soybean crop resulted the same results. Soil CO2 emissions increase with the increasing in soil temperature, and 73.4-73.9% of the variation could be explained by seasonal variation in soil temperature in wheat season. Similarly, 69.5-74.7% of the variation in soil CO2 emissions is recorded by seasonal variation in soil temperature in summer soybean season. Meanwhile (S1) increased the SOC and grain yield of wheat and soybean when compared to S0. Straw input increasing soil CO2, grain yield and SOC content, considering the benefits of straw inputs to crops yield and SOC content, It is concluded that the addition of straw improve agriculture production. However, the types of straw inputs in order to promote the sequestration of soil organic carbon with the decrease in greenhouse gas emission is the future research direction for agriculture development in Guanzhong region of China.