Effects of transforming forest land into terraced land on the characteristics of soil carbon, nitrogen, phosphorus and their stoichiometry in North Guangdong, China.

Abstract

To examine the effects of land use change on soil stoichiometry, we selected four kinds of land use soils in northern Guangdong: forest land (FL), sloping orchard (SO), dry land terraces (DLT) and paddy terraces (PT) to explore the changes of the contents, stocks and stoichiometry of organic carbon, nitrogen and phosphorus in the 20 a process of transforming from forest land into terraced land. Results showed that land use significantly changed the contents and stoichiometric characteristics of soil carbon, nitrogen and phosphorus. With the increase of soil depth, organic carbon (OC) and total nitrogen (TN) contents of DLT and PT decreased significantly, while FL and SO showed a "V"-shaped change trend. There was no difference in total phosphorus (TP) content among the four land use types. The OC content of PT was the highest, with an average value of 12.36 g·kg-1, followed by FL (10.32 g·kg-1) and DLT (8.80 g·kg-1), while SO was the lowest (5.96 g·kg-1). TN content was decreased in order of PT (1.01 g·kg-1)>DLT (0.78 g·kg-1)>FL (0.66 g·kg-1)>SO (0.33 g·kg-1). TP content of DLT (0.71 g·kg-1) was the highest, and SO (0.22 g·kg-1) was the lowest. C:N was between 8.87 and 22.94, and SO was the highest. C:P was between 8.73 and 81.74, N:P was between 0.77 and 5.13, with both of which being the highest in FL. Land use, soil depth and their interaction significantly affected the contents, stocks, and stoichiometric ratio of soil carbon, nitrogen and phosphorus, with soil bulk density, pH, and clay content as important influencing factors. The research results could provide a scientific basis for land use of subtropical low mountain forest land and rational fertilization of terraced ecosystems.