Spatial distribution and correlation of soil phosphorus

inorganic phosphorus forms

and enzyme activities in loessial soil and dark loessial soil under different land uses were studied on the Loess Plateau of Gansu Province.Results showed that as the depth of soil layer increased

inorganic phosphorus decreased

as well as organic phosphorus in dark loessial soil in orchard and vegetable garden.However

total phosphorus in farmland and alfalfa land increased with increased soil depth.There was a very significantly positive correlation between soil phosphorus and organic phosphorus in 0—20 and 20—40 cm soil layers for each land use type

as well as between soil phosphorus and total phosphorus.In terms of the average inorganic phosphorus content

Ca10—P

Ca8—P

Al—P

Fe—P

Ca2—P

and O—P were ranked in descending order.As the depth of soil layer increased

Ca8—P

Al—P

and Ca2—P in loessial soil decreased

but they increased in dark loessial soil in orchard

farmland

and vegetable garden.In terms of the correlation between soil inorganic phosphorus forms and enzyme activities

orchard

vegetable garden

farmland

wasteland

sea buckthorn forest

and alfalfa and tobacco lands were ranked in descending order.In terms of the correlation between soil inorganic phosphorus and soil enzyme activities

Al—P

Ca10—P

Ca2—P

Ca8—P

Fe—P

and O—P were ranked in descending order.