The invention relates to the technical field of soil fertilization, in particular to a plain area dry farmland thick and fertile
plough layer construction and productivity improvement method which comprises the following steps: in the first year, after corn is harvested, smashing straws, turning and burying the straws and returning the straws to the field, and in the next year, performing
soil preparation and
sowing by adopting flat-planting wide-narrow-row planting or
ridge-planting uniform-row planting; in the second year, after the corn is harvested, the whole
straw or smashed
straw covers and returns to the field,
straw row-collecting no-
tillage sowing is carried out in the next year, and flat-
cropping wide-narrow row planting is adopted for
sowing; in the third year, after the corn is harvested, the whole straw or smashed straw covers and returns to the field, straw row-collecting no-
tillage sowing is carried out in the next year, and flat-
cropping wide-narrow row planting is adopted for sowing. Through the implementation of the technical method, the thickness of a
plough layer of the dry farmland in the plain area is increased by 13-15 cm, the
nitrogen fertilizer utilization rate is increased by 10%-15%, and the
soil fertility level is increased by 0.5-1 grade.