Leaching Effect of Acid Rain on Phosphorus of Loess Soil

A leaching experiment was conducted using soil column simulation to investigate the release and transferring characteristics of phosphorus in three soils of Yangling Demonstration Zone,Shaanxi Province under erosion effects of five acid rain gradients.The results showed that acid rain resulted in soil acidification to some extent,which was controlled by the pH value of the acid rain,soil type,soil pH value,cation exchange capacity and organic matter content.The soils could be ranked in terms of acid rain buffering capacity in a descending order as humus layerparent material layeradhesive layer.With the increase of total leaching amount by acid rain,the total soil phosphorus release amount increased with a decreasing leaching rate.Soil phosphorus loss amount achieved the maximum value with acid rain that has a pH value of 5.The soils could be then ranked in terms of either the cumulative soil phosphorus release amount or the leaching rate in a descending order as humus layeradhesive layerparent material layer.Acid rain showed the strongest erosion effect on phosphorus of the humus layer.The acidification in the parent material layer and the adhesive layer occurred mainly in surface,while the acidification in the humus layer mainly occurred in the lower part.The most severe acidification by acid rain was found in the humus layer.Long-term acid rain leaching could lead to soil phosphorus loss and causes soil nutrient impoverishment.