尿素融合葡萄糖对潮土中尿素的水解及相关酶活性的影响

Fusion of glucose into urea affects the urea hydrolyzation and enzyme activities in fluvo-aquic soil

【目的】研究小分子有机物葡萄糖对尿素在石灰性潮土中的转化特征及相关土壤酶活性的影响,为小分子有机物在提高氮肥利用效率中的应用提供理论依据。【方法】将葡萄糖按0.5%、1%、5%和10%的比例与尿素熔融制成4种含葡萄糖尿素试验产品:GU0.5、GU1、GU5和GU10。采用土壤培养法,设置6个处理:不添加尿素对照(CK)、普通尿素(U)和4种含葡萄糖尿素(GU0.5、GU1、GU5、GU10),除CK外,其它处理施氮量均为N 0.3 g/kg,干土。肥料与土壤混匀装入培养瓶,于25℃下恒温培养,于培养第0.5、1、3、5、7、14及21天进行采样,进行土壤pH、铵态氮含量、硝态氮含量以及土壤脲酶活性的测定。另外,第0.5、1、3与5天采集的土壤样品测定尿素态氮含量;第3、5与14天采集的土壤样品测定β-葡萄糖苷酶、乙酰氨基葡萄糖苷酶和亮氨酸氨基肽酶活性。【结果】1)培养第0.5天,含葡萄糖尿素(GU)处理的土壤尿素态氮含量较普通尿素处理高了1.9%~12.2%;培养至第3天,含葡萄糖尿素加快了尿素的水解,且葡萄糖用量最高的尿素(GU10)水解最快;2)培养至第3~7天,4种含葡萄糖尿素处理的土壤铵态氮含量较普通尿素处理提高了19.0%~26.2%,硝态氮含量提高了16.5%~30.9%;3)与普通尿素处理相比,在培养至第3~14天,含葡萄糖尿素处理的土壤脲酶活性平均提高了6.9%~8.5%;培养至第3天,GU处理的土壤β-葡萄糖苷酶活性显著提高了6.3%~9.0%,GU10处理的土壤亮氨酸氨基肽酶活性显著提高了21.3%;培养至第5天,GU5和GU10处理的土壤乙酰氨基葡萄糖苷酶活性显著提高了47.8%和52.4%;4)在培养至第3天时,土壤铵态氮、矿质态氮含量与脲酶、β-葡萄糖苷酶以及乙酰氨基葡萄糖苷酶活性呈显著或极显著正相关,硝态氮含量与β-葡萄糖苷酶活性呈极显著正相关,pH与β-葡萄糖苷酶和亮氨酸氨基肽酶活性呈极显著负相关。【结论】将葡萄糖与尿素熔融结合为含葡萄糖尿素,可先减缓后促进尿素在潮土中的分解转化,增加了土壤矿质氮含量;施入土壤3~5天内对土壤脲酶、β-葡萄糖苷酶、乙酰氨基葡萄糖苷酶和亮氨酸氨基肽酶活性影响最大;矿质态氮在培养前期与相关土壤酶活性存在显著正相关关系,而土壤pH与相关土壤酶活性存在显著负相关关系。

【Objectives】The influence of glucose on the hydrolyzation of urea and the related enzyme activities was studied in fluvo-aquic soil,in order to provide a theoretical basis for utilizing low molecular organic compounds to improve nitrogen fertilizer use efficiency.【Methods】Glucose was added into urea through fusion method in rates of 0.5%,1%,5% and 10%,and four urea-glucose products were prepared as GU0.5,GUI,GU5,and GU10.An indoor constant-incubation experiment was conducted using the four products and common urea(U),taking no urea addition as control(CK).The N adding amount of each treatment was the 0.3 g/kg dry soil,except CK.The soil samples were collected on the half,1 st,3 rd,5 th,7 th,14 th,and 21 st day since the start of incubation.The contents of urea-N were determined in the soil samples of the half,1 st,3 rd and 5 th day.The soil pH,contents of NH4+-N and NO3--N,and urease activities were determined in all the collected samples.And the activities of β-glucosidase,N-acetyl-glucosaminidase and L-leucine aminopeptidase were analyzed in soil samples of the 3 rd,5 th,14 th day.【Results】1) On the half day,the contents of urea-N under GU treatments were increased by 1.9%-12.2%,compared with that under ordinary urea treatment.On the 3 rd day,the GU treatments accelerated the hydrolyzation of urea compared with common urea treatment,and the urea hydrolysis under GU10 treatment was significantly faster than under the others.2) Compared with common urea treatment,the GU treatments significantly increased the NH4+-N contents by 19.0%-26.2%,and NO3--N contents by 16.5%-30.9% on the days of 3-7;increased the soil urease activities by 6.9%-8.5% in average on the days of 3-14;increased β-glucosidase activity by 6.3%-9.0%,and GU10 treatment increased L-leucine aminopeptidase activity by 21.3% on the 3 rd day;GU5 and GU10 treatments enhanced the activity of N-acetylglucosaminidase by 47.8% and 52.4% respectively on the 5 th day.3) The contents of ammonium N and mineral N in soil were significantly or very significantly positively correlated with the activities of urease,β-glucosidase and N-acetylglucosaminidase on the 3 rd day.Nitrate N was very significantly and positively correlated with the activity of β-glucosidase.soil pH was very significantly and negatively correlated with the activity of [3-glucosidase and L-leucine aminopeptidase.【Conclusions】Fusion of glucose into urea can first slow down and then promote the hydrolyzation and transformation of urea in fluvo-aquic soil,and increase soil mineral N contents.Compared with common urea,four urea-glucose products can influence the activities of soil urease,β-glucosidase,N-acetylglucosaminidase and L-leucine aminopeptidase in different extents during the incubation,especially on the days of 3-5.Mineral N is significantly and positively correlated with the related soil enzyme activities,while soil pH is significantly and negatively correlated with them.