Abstract:Aimed to study the effect of intercropping on soil organic carbon storage and its nitrogen regulation effect, soil samples were collected from a 5-year field plot located experiment with maize monoculture, potato monoculture and maize and potato intercropping under different nitrogen application levels. Soil aggregates were graded by dry sieve method, and organic carbon content of aggregate in each size fraction was determined. The results showed that more than 92% of soil organic carbon was reserved in soil macro-aggregates (>2 mm) and small aggregates (2~0.25 mm). Intercropping increased the mass proportion of soil macro-aggregates (>2 mm) and small aggregates (2~0.25 mm), but the effect of intercropping on organic carbon contents of soil aggregates was related to nitrogen application. Compared with the two monocultures, intercropping under low nitrogen (N1) and conventional nitrogen (N2) application increased total organic carbon reserves of soil, but did not significantly affect or reduce the organic carbon reserves under no nitrogen (N0) and high nitrogen (N3) application. Among them, intercropping produced the strongest intercropping carbon sequestration advantage at low nitrogen (N1) by increasing the mass proportion of soil macro-aggregates (>2 mm) and their organic carbon contents, where the total organic carbon reserves of soil were 24.8% and 5.7% higher than those of maize monoculture and potato monoculture respectively. Therefore, proper application rates of nitrogen fertilizer could give full play to intercropping effect and effectively increase soil organic carbon reserves.