The invention discloses a method for restraining the
discharge of
nitrous oxide in a farmland, and the method is applicable to a
paddy field and a
dry land. The method comprises the following steps of: 1) production of biologic black
charcoal by thermally
cracking straws: collecting the straws of farm crops, atmospherically
drying or airing the straws so that the
moisture content of the straws is lower than 20%, thermally
cracking and carbonizing the straws to obtain the biologic black
charcoal, then
grinding the biologic black
charcoal, sieving the ground biologic black charcoal, and mixing and homogenizing the sieved biologic black charcoal to obtain the biologic black charcoal with particle diameters being smaller than 0.25 mm; and 2)
soil treatment by virtue of the biologic black charcoal: after the preceding crops are harvested, uniformly spreading the biologic black charcoal on the surface of soil, plowing and harrowing the soil so that the biologic black charcoal is uniformly mixed in the soil of a
plough layer, for the
paddy field, after the
soil treatment, irrigating and flooding water for 2-5 cm,
transplanting paddies after 3-5 days, directly planting the crops in the
dry land, and in the management measures of the farmland, keeping
irrigation, fertilization and
plant protection consistent with the management of a local farmland. By virtue of
field observation in the growth period of the crops, the
discharge of the N2O (
nitrous oxide) in the soil in the paddy fields in the Taihu plain and the dry lands in the Huang-Huai-Hai plain for the crops such as the paddies, corns and the like can be respectively reduced by 31%-58% and 11%-42%.