Effects of fertilization and mulching with plastic film on profile distribution and dynamics of Olsen-P in brown earth

A long term located experiment with different fertilization treatments in Shenyang Agricultural University and an investigation of nearby brown earth under different land use patterns were carried out to study the profile distributions(0100 cm) and dynamics of Olsen-P during the whole growth stage.Four fertilization treatments were involved in this experiment: no fertilization,single nitrogen application,single organic fertilizer application,combine application of organic and chemical fertilizer.The results showed that contents of Olsen-P in 020 and 60100 cm of the crop land were higher than that in 2060 cm.The contents of Olsen-P in native soils(grassland and woodland) increased with the deepening of soil layer in 0100 cm.Contents of Olsen-P in the treatments applied organic, organic and chemical fertilizers combined were higher than that in no fertilization and single nitrogen application.Under plastic film mulching condition,Olsen-P in 040 cm soils,except 020 cm soil with single organic fertilizer application,were not statistically significantly decreased.In conclusion,using organic or organic and chemical fertilizer combined were effective measures to accumulate Olsen-P of soils.Deep placement of fertilizer should be employed for the supplement of Olsen-P.Mulching did not have significant effects on the distribution of Olsen-P in soil profile of brown earth in this study.