Abstract:
Objective Understanding the dynamics of soil total phosphorus (TP) in agricultural land and its influencing factors is helpful to formulate rational management measures of field phosphorus fertilizer and scientifically prevent and control non-point source pollution.
Method Based on 160 soil samples obtained during the period of the Second Soil Survey and 175 soil samples collected in 2016 ~ 2017, this study used general statistics and variance analysis to investigate the TP dynamics in the topsoil (0-20 cm) of the agricultural land across the Chengdu Plain in the past 40 years and the correlations with agricultural land-use change and parent materials.
Result The results showed that TP contents in the surface soil significantly increased from 0.48 g kg−1 to 0.95 g kg−1, with an increase of 97.92%. Compared with the traditional rice-wheat/rapeseed rotation land in the 1980s, TP contents in rice-wheat/rapeseed rotation land, rice-vegetable rotation land and afforested land increased by 79.17%, 150.00% and 85.42% in 2016 ~ 2017, respectively. The increase of TP contents of soils formed from Q3 (Quaternary Pleistocene) old alluvium was the highest (147.06%), followed by Q4 (Quaternary Holocene) grey-brown alluvium (115.56%) and Q4 grey alluvium (81.82%). Compared with the traditional rice-wheat/rapeseed rotations, soils formed from Q3 old alluvium (132.35%) showed a much higher increase of TP accumulation than those of soils formed from Q4 grey-brown alluvium (115.56%) and Q4 grey alluvium (81.82%) for rice-vegetable rotations; whereas, afforestation only led to the increase of TP accumulation in soils formed from Q3 old alluvium, decreased TP content in soils formed from Q4 grey-brown alluvium, and caused unobvious change of TP contents in soils formed from Q4 grey alluvium.
Conclusion The results indicated that the change of agricultural land use had altered the characteristics of soil phosphorus accumulation, but it’s effect on topsoil TP accumulation depended on the type of parent material.