腐植酸与尿素结合工艺对尿素在潮土中转化的影响

通过研究腐植酸与尿素结合工艺对尿素在土壤中转化的影响,为腐植酸尿素生产工艺的选择提供科学依据。在石灰性潮土上进行土壤培养试验,设置8个处理:不施尿素(CK)、普通熔融尿素(U)、0.5%添加量的腐植酸(HA0.5)、5%添加量的腐植酸(HA5)、腐植酸添加量为0.5%的掺混腐植酸尿素(HA+U0.5)、腐植酸添加量为0.5%的熔融腐植酸尿素(HAU0.5)、腐植酸添加量为5%的掺混腐植酸尿素(HA+U5)、腐植酸添加量为5%的熔融腐植酸尿素(HAU5),分析转化过程中的尿素残留量、铵态氮含量、硝态氮含量、土壤p H值及土壤脲酶活性。结果表明:(1)与对照尿素U相比,腐植酸尿素均可降低氨挥发,平均降低23.5%;添加5%腐植酸,熔融腐植酸尿素较掺混腐植酸尿素可显著降低氨挥发累积氮量13.5%。(2)两种工艺制备的腐植酸尿素均可在一定程度上减缓尿素水解。总体上,在培养的第0.25、0.5、1、2 d,腐植酸尿素处理的尿素残留量分别较对照尿素U高出29.2%、22.0%、10.3%、11.8%;熔融腐植酸尿素处理的尿素残留量较掺混腐植酸尿素显著高出21.3%~50.8%。(3)培养结束时,腐植酸尿素较对照尿素U可提高硝态氮含量3.8%~12.6%;熔融腐植酸尿素较掺混腐植酸尿素可提高硝态氮7.6%~13.8%。(4)在培养第0.25、0.5 d,与对照尿素U相比,掺混腐植酸尿素可分别降低脲酶活性19.1%、12.3%,而熔融腐植酸尿素可显著提高脲酶活性48.5%、102.1%。以上结果表明腐植酸无论与尿素以何种工艺结合均可降低氨挥发、减缓尿素水解,且熔融工艺的效果较掺混工艺更为明显。

Effect of the combination of humic acid and urea on the conversion of urea in fluvo-aquic soil

By studying the influence of the combination of humic acid and urea on the conversion of urea in soil,this paper provides a scientific basis for the selection of the production process of humic acid urea. Soil cultivation test was conducted on fluvo-aquic soil,and 8 treatments were set up:without urea(CK),the common molten urea(U),0.5% of added amount of humic acid humic acid(HA0.5),5% of added amount of humic acid(HA5),0.5% humic acid added amount mixed with urea(HA+U0.5),0.5% humic acid added amount to the molten urea humate(HAU0.5),5% humic acid added amount mixed with urea(HA+U5),5% humic acid added amount to the molten urea humate(HAU5). The urea residue,ammonium nitrogen content,nitrate nitrogen content,soil pH value and soil urease activity during the conversion process were analyzed. The results showed that:(1)Compared with U,humic acid with urea reduced ammonia volatilization by 23.5% on average. When 5% humic acid was added,melting humic acid and urea significantly reduced the accumulation of ammonia volatilized nitrogen by 13.5% compared with mixing humic acid and urea.(2)Both humic acid and urea prepared by the two processes slowed down the hydrolysis of urea to a certain extent. On the whole,the residues of urea treated with humic acid with urea were 29.2%,22.0%,10.3% and 11.8% higher than those of U at 0.25,0.5,1 and 2 d after cultivation. The residue of urea treated by melting humic acid and urea was 21.3% ~ 50.8% higher than that of mixed humic acid with urea.(3)At the end of cultivate,compared with U,humic acid with urea increased the mineral nitrogen content by 3.8% ~ 12.6%;Compared with mixed humic acid and urea,melting humic acid and urea increased mineral nitrogen by 7.6% ~ 13.8%.(4)On the 0.25 and 0.5 d of cultivation,compared with U,the mixed humic acid urea reduced the urease activity by 19.1% and 12.3%,while the fused humic acid urea significantly increased the urease activity by 48.5% and 102.1%. The above results showed that humic acid could reduce ammonia volatilization and slow down urea hydrolysis no matter by which process it combines with urea,and the effect of melting process is more obvious than mixing process.