不同栽培模式对冬小麦根区土壤不稳定氮库、酶及氨挥发的影响

Effects of different cultivation patterns on soil labile nitrogen pool, enzymes and ammonia volatilization in the root zone of winter wheat

  • 摘要: 通过长期定位试验研究不同栽培模式下冬小麦根区土壤不稳定氮库及土壤酶活性对氨挥发的影响。本实验采用裂区实验设计,主区为常规栽培、秸秆还田和地膜覆盖,副区为不施氮、常规施氮和常规减氮20%。在第5季冬小麦播种后42、166、194和217天,采集0-20 cm小麦根区土,测定土壤硝铵态氮、微生物生物量氮、土壤硝酸还原酶、羟胺还原酶和脲酶活性。并于小麦季收集农田土壤氨挥发,分析氨挥发对栽培模式、土壤不稳定氮库及土壤酶的响应。结果表明:地膜覆盖施肥处理小麦全季氨挥发积累量(6.41~7.38 kg hm-2)显著低于相同施肥水平的秸秆还田(8.37~9.45 kg hm-2)和常规耕作处理(8.81~11.06 kg hm-2)(p<0.05)。秸秆还田处理微生物生物量氮含量显著高于常规耕作和地膜覆盖处理(p<0.05)。秸秆还田处理下土壤氨挥发与土壤铵态氮、微生物生物量氮与脲酶活性显著正相关(p<0.05)。在地膜覆盖处理下,土壤氨挥发与土壤铵态氮、微生物生物量氮、羟胺还原酶与脲酶活性均呈显著正相关(p<0.01)。本研究描述了不同栽培模式下冬小麦根区土壤不稳定氮库及土壤酶活性对氨挥发的影响,可为后续减少氨挥发损失提高氮肥利用率提供理论支撑。

     

    Abstract: A long-term experiment was conducted to investigate the effects soil labile nitrogen pools and soil enzyme activities have on ammonia volatilization in the root zone of winter wheat under different cultivation modes. A split-zone experimental design was used in this experiment, The main zones were conventional cultivation, straw return, and film mulching, while the secondary zones were no nitrogen application, conventional nitrogen application, and conventional nitrogen reduction by 20%. 0-20 cm of wheat root zone soil was collected 42, 166, 194, and 217 days after sowing of winter wheat in the fifth season and inter-root soil of wheat was collected 42 days after sowing to determine soil nitrate-ammonium nitrogen, microbial biomass nitrogen, soil nitrate reductase, hydroxylamine reductase, and urease activities. The ammonia volatilization from agricultural soils was also collected during the wheat season in order to analyze the response of ammonia volatilization to the cultivation pattern, soil labile N pools, and soil enzymes. The results found total season ammonia volatilization accumulation in wheat to be significantly lower (p<0.05) in the film mulching treatments (6.41-7.38 kg hm-2) than in the straw return (8.37-9.45 kg hm-2) and conventional tillage treatments (8.81-11.06 kg hm-2) with identical fertilization levels. The microbial biomass N content was found to be significantly higher (p<0.05) in the straw return treatment compared to the conventional tillage and film mulching treatments. Soil ammonia volatilization was found to have a significant positive correlation with soil ammonium nitrogen, microbial biomass nitrogen, and urease activity under straw return treatment (p<0.05). It also had a significant positive correlation with soil ammonium nitrogen, microbial biomass nitrogen, hydroxylamine reductase, and urease activity under mulch treatment (p<0.01). This study describes the effects soil labile N pools and soil enzyme activities have on ammonia volatilization in the root zone of winter wheat under different cultivation modes and this can provide theoretical support for subsequently reducing ammonia volatilization losses and improving the utilization of N fertilizer.

     

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