施氮方式及测定方法对紫色土夏玉米氨挥发的影响

以川中丘陵区紫色土为对象,研究了撒施尿素添加脲酶抑制剂及尿素深施对夏玉米季氨挥发的减排效果,为合理施肥和减少农田氨排放提供依据;同时,对比风洞法和密闭室连续抽气法测定氨挥发的结果,为准确定量农田氨挥发提供方法依据。设置5个施氮方式处理,分别为:不施氮(CK);农民传统施氮——雨后撒施尿素(BC);撒施添加有Limus(德国BASF公司新开发的脲酶抑制剂)的尿素(BC+Limus);尿素一次性条施(Band1);尿素分两次条施(Band2)。除不施氮处理外,其他处理施氮量均为150 kg·hm~(-2),各处理采用密闭室连续抽气法测定氨挥发。另外,选取农民传统施氮处理用风洞法测定氨挥发,以研究不同测定方法对氨挥发损失量的影响。结果表明:紫色土夏玉米季农民传统的施氮方式氨挥发损失率可高于40%,而处理BC+Limus、Band1、Band2的氨挥发损失率分别为4.8%、3.8%、1.3%,分别比处理BC减少了90%、92%和97%的氨挥发损失,均具有很好的减排效果。密闭室连续抽气法测定氨挥发量稍高于风洞法,氨挥发损失率分别为48.4%和41.9%,但差异不显著。

Effects of different fertilization and measurement methods on ammonia volatilization of summer maize in purple soil

Soil properties, local climatic conditions and fertilization method in purple soil regions may significantly affect ammonia volatilization(AV). In this study, the effects of different fertilization methods on AV from purple soil were investigated during summer maize growth in middle Sichuan Province. Two different AV measurement methods(i.e., wind tunnel method and continuous airflow enclosure method) were compared to better quantify ammonia emissions from croplands. Five fertilization methods with three replicates were used in the experiment included CK(no nitrogen fertilizer), BC(broadcast urea, which is the local conventional practice), BC+Limus broadcast urea amended with urease inhibitor Limus(a new urease inhibitor developed by BASF)], Band1(band urea once), Band2(band urea twice). The AV in all the treatments was determined by enclosure method. For BC treatments, AV was monitored by a wind tunnel system simultaneously. Results showed that AV loss rates were greater than 40% in BC, but only 4.8%, 3.8% and 1.3% in BC+Limus, Band1 and Band2, respectively, a reduction of 90%, 92%, and 97% as compared with BC. Ammonia loss rate(48.4%) measured by continuous airflow enclosure method was slightly higher than that by wind tunnel method(41.9%), but no significant difference between them was found.