Effects of Biochar on Soil Nutrients and Nitrogen Leaching in Anthropogenic-Alluvial Soil

Anthropogenic-alluvial soil was the main species in Ningxia irrigation district. The crude farming methods are used in the paddy planting,such as uncontrolled irrigation and excessive fertilization,leading to a high leaching of nitrate nitrogen to the surface water. Soil column leaching method was used to study the effect of different amount of biochar application on nitrogen leaching and soil nutrient availability in anthropogenic-alluvial soil. The results showed that there was no significant difference in soil pH,the content of total salt and phosphorus between the biochar addition treatments and control. but,the content of total soil nitrogen,available phosphorus,available kalium was significantly increased with the biochar application amount. Applying biochar significantly reduced the concentration and leaching amount of nitrate nitrogen. 2% biochar addition reduced the nitrate nitrogen leaching by 49% when compared with the control. The leaching peak of ammonium nitrogen was delayed with the increase of biochar addition. The significant decrease of ammonium nitrogen leaching( 18%) was found only in the treatment of 10% biochar addition. However,the opposite trend was found in the other biochar addition,compared with the control. Whether the species of biochar affect nitrogen leaching in anthropogenic-alluvial soil needs to be further studied.