Temporal and spatial variability of nitrogen in rice–wheat rotation in field scale

Traditional statistics and geostatistical methods were used to study the spatial and temporal variation of soil nitrogen in rice–wheat rotation field in Changshu. Soil samples were collected after the wheat and rice harvest by a grid spacing of 30 m in three depths of soil profiles, which were 0–15 cm, 15–28 cm, 28–42 cm. The contents of soil total nitrogen and nitrate nitrogen in rice fields were lower than that in wheat fields. The contents of total nitrogen and nitrate in the surface layer (0–15 cm) were higher than that in subsurface (15–28 cm) and bottom (28–42 cm) layers. The spatial distribution of soil total nitrogen and nitrate contents in the crop growing season was affected by the agricultural fertilization. The study is to provide a basis for rational fertilization.