[Effects of land use type on spatiotemporal distribution of soil nutrients in Dianchi watershed, Yunnan Province of Southwest China].

Surface soil samples were monthly collected from six land use types (abandoned greenhouse field, forest land, sloped farmland, table land, flat vegetable land and greenhouse field) in Dianchi watershed of Yunnan to determine the soil pH and the contents of soil organic matter (OM), total nitrogen (TN), and total phosphorus (TP), aimed to understand the effects of different land use types on the spatiotemporal distribution of the soil nutrients. The soil pH, SOM, TN and TP, contents, and soil C/N differed significantly with soil land use types. The soil pH was in the order of abandoned greenhouse field > flat vegetable land > greenhouse field > table land > sloped farmland > forest land; the OM content was in the sequence of abandoned greenhouse field > flat vegetable land > greenhouse field > sloped farmland > forest land > table land; the TN content was in the order of greenhouse field > flat vegetable land > abandoned greenhouse field > sloped farmland > table land > forest land; the TP content was in the order of flat vegetable field > greenhouse field > abandoned greenhouse field > sloped farmland > table land > forest land; and the C/N ratio was in the sequence of forest land > sloped farmland > flat vegetable plot > table land > abandoned greenhouse field > greenhouse field. The OM, TN and TP contents were affected by fertilization, irrigation, field cultivation and season. All the test parameters had the highest values in rainy season, which could be related to the local top-dressing habits. There were significant positive correlations among the TN, TP and OM under all the land use types. In greenhouse field and abandoned greenhouse field, due to the severe human disturbances, the soil pH and OM, TN and TP contents were obviously higher than those in forestland and table land.