不同降雨年份控释尿素与普通尿素配施对夏玉米产量、氮素利用及经济效益的影响

  【目的】  在干旱和正常降雨年份，比较控释尿素与普通尿素不同配施比例对玉米产量和经济效益的影响，为夏玉米养分科学管理提供依据。  【方法】  试验于2017—2018年在河南省禹州市顺店镇进行，该地2017年6—9月降雨量为210.9 mm，属少雨干旱年份；2018年6—9月，降雨量为533.9 mm，属降雨正常年份。试验设置控释尿素 (N 45%) 与普通尿素 (N 46%) 的配比分别为1∶9、2∶8、3∶7、4∶6、5∶5，施氮量均为N180 kg/hm2。于拔节期、大喇叭口期、开花期、乳熟期、成熟期取植株样品，测定植株全氮含量；于成熟期，测定玉米产量同时测试土壤无机氮含量。  【结果】  不同降雨年份玉米产量差异显著，相同处理下干旱年份 (2017) 与降雨正常年份 (2018) 相比玉米减产36.5%～53.4%。在降雨正常年份，与仅施普通尿素相比，控释尿素与普通尿素以4:6配比的玉米产量提高10.1%，经济效益提高15.8%。在干旱年份，与仅施普通尿素处理相比，控释尿素与普通尿素配施处理的玉米产量有所下降，其中CRU4显著减产22.9%，经济效益降低56.7%，当控释尿素与普通尿素比例为4∶6时减产幅度达到最大，经济效益也最低。相同配施处理下，在降雨正常年份玉米花后氮素累积比干旱年份增长108.0%～1175.7%，氮肥偏生产力增长57.4%～114.6%。在干旱年份，控释尿素与普通尿素配施处理的表层土壤硝态氮含量比降雨正常年份高52.3%～131.9%。在降雨正常年份，控释尿素与普通尿素配施处理土壤表层 (0—30 cm) 硝态氮含量均高于仅施普通尿素的处理。  【结论】  与正常降雨年份相比，干旱可导致玉米减产36.5%～53.4%，植株干物质累积量、氮素累积量、氮肥偏生产力均有所降低，土壤硝态氮残留量升高52.3%～131.9%。正常降雨量下，控释尿素与普通尿素配施能够提高玉米氮素累积量和经济效益，控释尿素与普通尿素在3∶7的配比下能获得最佳经济效益。

Yield,nitrogen use and economic benefit of summer maize under different ratios of controlled-release and ordinary urea combination in normal and dry rainfall years

  【Objectives】  The yield and economic effects of controlled-release and ordinary urea combination in different ratios were compared in drought and normal rainfall years, which will help to realize more efficient use of controlled-release urea.  【Methods】  The experiment was carried out in Shundian Town, Yuzhou City, Henan Province from 2017 to 2018. From June to September of 2017 and 2018, the rainfall were 210.9 mm and 533.9 mm, so 2017 and 2018 were defined as drought and normal year, respectively. Under the same N application rate of 180 kg/hm2, the controlled release urea (CRU, N 45%) and ordinary urea (N 46%) was mixed in ratio of 1∶9, 2∶8, 3∶7, 4∶6, 5∶5, respectively, and topdressed in one time. Plant samples were taken at the main growing stages, and the N contents were analyzed. At maturity, yields were investigated, and soil inorganic N content was determined.  【Result】  The maize yield in 2017 and 2018 was significantly different, those in the same treatment in 2017 was decreased by 36.5% to 53.4% than those in 2018. In 2018, compared with ordinary urea treatment, the maize yield was increased by 10.1% and the economic benefit by 15.8% in the treatment with the ratio of CRU and urea of 3∶7. In 2017, compared with urea, the maize yield decreased by 22.9%, and the economic benefit decreased by 56.7% in the treatment of CRU to urea ratio of 4∶6. Under the same combination treatment, N accumulation after maize blossom in 2018 was 108.0%–1175.7% higher, and N partial productivity was 57.4%–114.6% higher than in those in 2017. In 2017, the NO₃–-N contents in surface soil of treatments were 52.3% to 131.9% higher than those in 2018. In 2018, the NO₃–-N contents of 0–30 cm soil in the CRU treatments were all higher than that in urea.  【Conclusion】  Compared with normal rainfall year, maize yields are decreased by 36.5%–53.4% due to drought, N accumulation and N partial factor productivity are also decreased, and soil N residue is increased by 52.3%–131.9%. In normal rainfall, the combined application of controlled release urea and ordinary urea can improve the N accumulation and economic benefits. Under the tested conditions, the recommended combination ratio of controlled-release and ordinary urea is 3∶7.