目前广大农村,把大量的作物秸秆作燃料烧掉了。这种作法是极不合算的。农作物秸秆,直接用作燃料,最后只能得到少量的草木灰。例如:二千斤玉米秆,燃烧后最多只能得到300斤草木灰。草木灰的主要养分是钾,而其它养分,尤其是氮素在燃烧过程中都挥发掉了。这是一项莫大的浪费!如果把秸秆用作沼气发酵,有机质的30—40%被沼气细菌分解生成沼气,其余60—70%则部分地变成腐殖质。腐殖质能够改良土壤结构,这是化学肥料所不及的。从作物秸秆的养分含量(见表1)可看出:每百斤玉米秆相当于3.05斤 At present, most rural areas burn a large amount of crop straw for fuel. This approach is extremely uneconomical. Crop straws, used directly as fuel, can only get a small amount of ash eventually. For example: two kilograms of corn stalks, burning up to only get 300 kg of ash. The main nutrient of ash is potassium, while other nutrients, especially nitrogen, volatilize during the combustion process. This is a great waste! If straw is used as biogas fermentation, 30-40% of organic matter is decomposed by biogas bacteria to generate biogas, while the remaining 60-70% is partially humified. Humus can improve the soil structure, which is beyond the reach of chemical fertilizers. From the crop straw nutrient content (see Table 1) can be seen: per 100 kg of corn stalks equivalent to 3.05 pounds