Abstract: To investigate the effects of different straw returning modes on spatial distribution and accumulation of nitrate nitrogen in soil，a 16-year long-term fix-location experiment has been conducted in an experimental station in Shouyang，Shanxi Province，which is located in the typical partially drought semi-humid climate zone． The results showed: Straw returning effectively elevated the crop production，and nitrogen surplus was also increased，which raised the risk for nitrogen leaching． The accumulation of nitrate nitrogen primarily occurred at 0 - 200 cm depth in longitudinal section of soil in different straw return treatments，and apparent nitrate nitrogen accumulation peaks appeared at soil depth below 80 cm． The treatment of straw return after livestock digestion brought about the largest amount of nitrogen surplus and therefore showed the highest nitrate nitrogen accumulation，with two nitrate nitrogen accumulation peaks appeared at 80 - 100 cm and 200 - 220 cm depths， respectively; the nitrate nitrogen accumulation in the lower soil layer was raised considerably， resulting in increased risk for nitrogen leaching． Although the lowest accumulation of nitrate nitrogen was seen in the treatment of straw returning by mulch， the accumulation at 200 - 300 cm depth accounted for 25． 63% of the total accumulation， suggesting the highest risk for nitrogen leaching among all treatments

Key words: Straw returning, Nitrate nitrogen, Accumulation, Leaching risk, Dryland soil

CLC Number: 

• S143.1