不同栽培模式和施氮量对小麦-玉米轮作体系土壤供氮特性的影响

Effects of different cultivation patterns and nitrogen fertilization on soil nitrogen supply of in the wheat-maize rotation system

以6年的小麦-玉米轮作定位试验不同处理为对象,研究了不同栽培模式及施氮对土壤供氮特性的影响。结果表明,与常规对照模式相比,覆草模式显著增加了土壤酸解总氮及有机氮各组分的含量,以及土壤微生物量氮含量及氮素矿化势N0;垄沟模式(垄上覆膜、沟内覆草)土壤酸解总氮及氮素矿化势有所增加,幅度小于覆草模式,但降低了土壤微生物量氮含量。随着施氮量的增加,土壤酸解总氮含量增加,其中以氨基酸氮、氨基糖氮及氨态氮含量的增加尤为明显;施氮还提高了土壤氮素矿化势,但降低了土壤微生物量氮含量,以施N 240 kg/hm2处理最为明显。栽培模式和施氮量对土壤酸解总氮影响的交互效应达显著水平(P<0.05)。土壤氮素矿化势、微生物量氮与氨基酸氮和酸解未知态氮间呈显著相关性(P<0.05),说明土壤微生物量氮及氨基酸氮和酸解未知态氮组分可能是土壤可矿化态氮的主要贡献者。

A six year positioning experiment of wheat-maize rotation was used to compare the effects of different cultivation patterns and nitrogen application rates on soil N supplying ability.The results show that compared with the conventional control treatment（CC）,the contents of total hydrolysable N（THN）,microbial biomass nitrogen（SMBN） and mineralized nitrogen potential（N0） of soil under the straw mulching treatment（SM） are significantly increased,and the fractions of different forms of soil organic nitrogen are enhanced as well.The contents of THN and N0 are increased under the furrow cultivation pattern（FM） and the increased rates are lower than those of the SM pattern,while the content of SMBN is decreased.The contents of THN,N0,amino acid N（AAN）,amino sugar N（ASN）,ammonium N（AN） are also increased under the nitrogen fertilization,while the content of SMBN is decreased,especially for the N 240 kg/ha rate.The interaction between cultivation pattern and nitrogen application rate on fractions of different forms of organic nitrogen in soil is not statistically significant（P0.05）.The correlation analysis results indicate that there are significantly positive correlations between N0,SMBN,AAN,hydrolysable unidentified N（HUN）（P0.05）,which implies the last three fractions maybe the major contributors to the soil mineralized nitrogen.