[Distribution characteristics of soil phosphorus in maize belt farmlands of Northeast China].

The study on the vertical distribution and latitudinal differentiation of soil total and organic phosphorus (P) down to 100 cm depth in maize belt farmlands of Northeast China showed that in Hailun and Harbin of Heilongjiang Province, Gongzhuling of Jilin Province, and Dashiqiao of Liaoning Province, soil total P decreased with soil depth, being significant higher in 0-40 cm than in 40-100 cm (P < 0.01). In Dehui of Jilin Province and in Changtu and Shenyang of Liaoning Province, soil total P was relatively lower in 40-60 cm, but no significant difference was observed among different layers. Soil organic P was significantly higher in 0-20 cm than below 20 cm (P < 0.05). Soil total and organic P increased with increasing latitude (P < 0.05). The differences in climate conditions and soil types were considered as the main reasons induced the latitudinal differentiation of soil P. Soil total and organic P were significantly correlated with soil organic carbon (P < 0.01), indicating that soil organic matter was one of the most important factors affecting the soil P content and its distribution in maize belt farmlands of Northeast China.