Effect of different Nitrogen Application Methods on Soil Organic Matter and Nitrogen Content

Straw returning can reduce environmental pollution and improve the fertility of soil.The research investigated different nitrogen application methods on spatial and temporal dynamic of soil organic matter and nitrogen content under straw returning.On the condition of straw returning,0～20 cm planosol organic matter increased with growing process,reached maximum at harvest stage,20～30 cm reached maximum at R4 stage;The content of planosol total nitrogen was expressed in a single peak curve with growing process,reached maximum at R2～R4 stage;The content of planosol available nitrogen was expressed in a single peak curve with growing process,0～20 cm soil reached maximum at R5 stage,20～30 cm soil reached maximum at R2 stage.The content of 0～20 cm soil organic matter increased by the nitrogen fertilizer as seed manure,10～30 cm soil organic matter content increased by nitrogen topdressing;The nitrogen applied as seed fertilizer increased soil total nitrogen content before R2 stage,while nitrogen topdressing had little effect on soil total nitrogen content.The nitrogen fertilizer application as seed fertilizer decreased the content of 20～30 cm soil available nitrogen,while it had little effect on 0～20 cm soil,soil available nitrogen content increased by nitrogen topdressing.The content of soil organic matter and total nitrogen,soil organic matter and available nitrogen,available nitrogen and total nitrogen of planosol showed a significantly positive correlation.