秸秆腐解对不同氮肥水平土壤脲酶活性的影响

本文利用黑龙江大学呼兰校区秸秆还田试验为平台,探讨秸秆还田后不同施氮量下土壤脲酶活性的动态变化特征,明确农田黑土玉米秸秆腐解下土壤氮素含量与脲酶活性的关系。试验以秸秆腐解和不施秸秆为主区,不同氮肥水平(纯N)(0、135kg/hm2、180kg/hm2、225kg/hm2)为副区,测定了土壤全氮、碱解氮及脲酶活性,试验结果表明：两种秸秆处理的土壤脲酶活性变化趋势均随玉米生育期的延长增加,在拔节期达到最高后降低；与无秸秆处理相比,在施氮量为180kg/hm2、225kg/hm2秸秆腐解处理可显著提高土壤脲酶活性(p&;lt;0.05),而施氮量为0、135kg/hm2时虽提高了脲酶活性,但未达到显著水平(p&;gt;0.05)；土壤碱解氮、土壤全氮的变化趋势与土壤脲酶活性的变化趋势一致,均为随施氮水平的增加而增加；相关分析显示,土壤脲酶活性与土壤全氮、碱解氮呈极显著正相关。

Effects of Straw Decomposition on Soil Urease Activity at Different Nitrogen Fertilizer Levels

Based on the straw returning experiment in Hulan campus of Heilongjiang University, this study focused on the dynamic of soil urease activity at different nitrogen application rates after straw returning to the field, and tried to clarify the relationship between soil nitrogen content and urease activity under accelerated decomposition of corn straw in black soil. In the experiment, the soil total nitrogen, available nitrogen, and urease activities were measured in the main areas of straw decomposition and no straw application, with different nitrogen fertilizer levels (pure N) (0,135 kg/hm2,180 kg/hm2,225 kg/hm2) as sub-areas. The results showed that the changing trend of soil urease activity under the two straw treatments increased with the extension of maize growth period and decreased after reaching the maximum in the jointing stage. Compared with the treatment without straw, accelerated straw decomposition with nitrogen application rates of 180 kg/hm2 and 225 kg/hm2 could significantly improve soil urease activity (p< 0.05), while nitrogen application rates of 0 kg/hm2 and 135 kg/hm2 increased urease activity but no significant difference was detected(p>0.05). The changing trend of soil available nitrogen and soil total nitrogen is consistent with the change trend of soil urease activity, both of which increase with the increase of nitrogen application level. Significantly positive correlations between soil urease activity and total nitrogen or available nitrogen were observed in this study.