长期稻草还田对烟田土壤氮素矿化特征的影响

为探明稻草还田对烟田土壤氮素释放的影响,进而有效调控并为配套的施肥技术提供理论依据,采用室内培养和田间原位培养试验,研究了长期稻草还田对烟田土壤有机氮矿化特征和进程的影响。结果表明:稻草还田提高了土壤氮矿化潜力(N0值)和矿化速率(k0),连续还田5年土壤的N0值为92.11kg/hm2,比对照增加了23.78%;稻草还田促进了烟田土壤氮的矿化,烟株生长期内还田5年的土壤矿化氮量为94.94kg/hm2,比对照高17.67%。在烟株生长中后期,稻草还田的烟田表层土壤无机氮数量明显增加。稻草还田增加了土壤微生物量氮,移栽时,还田5年土壤微生物量氮比对照增加20.18%,采烤后则高出40.71%。稻草还田1年后土壤微生物量氮处于调整平衡阶段。长期实行稻草还田提高了烟田土壤氮供应能力,增加了上部烟叶全氮和烟碱含量过高的风险。

Effect of Rice Straw Returning on Tobacco Field Soil Nitrogen Mineralization

Incubating trials in lab and field were carried out to study the effect of long-term returning rice straw on the characteristics and processing of soil organic N mineralization in tobacco field.Lab trials proved that long-term rice straw returning had a positive effect on the soil organic N mineralization with improved potential and rate.The mineralization potential of the 6-years returning soil was 92.11 kg/hm2,and was 23.78% greater than that in the non-straw returning.Compared with control,the rice straw returning could advance the soil N mineralization.The net mineralization in tobacco growth period increased by 17.67% and 15.30% by the rice straw returned 5-years and 1-year respectively.In the tobacco field soil incorporated rice straw,the amount of soil inorganic N was enhanced and effected the soil N mineralization positively during the middle and late growth period of tobacco.The soil microbial biomass N in straw incorporating soil was 20.18% greater than that in the non-straw incorporating at beginning of transplantation,and was 40.71% greater at ending of harvest stage.The soil microbial biomass N in rice straw returning soil alternate during the first year and did not be stable at a new level.