腐植酸尿素对玉米产量及肥料氮去向的影响

Effects of humic acid urea on maize yield and the fate of fertilizer nitrogen

【目的】研究腐植酸尿素对玉米干物质量、籽粒产量及肥料氮去向的影响,以期为传统尿素产品的提质增效及新型腐植酸尿素肥料的研制提供理论与实践依据。【方法】以玉米品种郑单958为供试作物,以自制的腐植酸尿素为供试肥料,运用15N同位素示踪技术,开展土柱栽培试验,设置不施氮肥对照(CK)、普通尿素(U)和腐植酸尿素(HAU)3个处理,所有肥料均作为基肥一次性施入土柱0—30 cm土层。玉米成熟后,采集植株地上部样品进行考种,同时,分别测定玉米叶片、茎秆、苞叶、穗轴、籽粒的干物质量、氮素含量和^(15)N丰度;分别采集0—15 cm、15—30 cm、30—50 cm、50—70 cm、70—90 cm土层的土壤样品,测定其氮素含量和15N丰度。【结果】各处理玉米植株地上部及各器官(苞叶除外)干物质量由低到高为CK<U<HAU,而玉米各器官的干物质量占该植株地上部干物质总量的比例在不同处理下的差异均未达到显著性水平;与U处理相比,HAU处理玉米地上部干物质量平均提高13.8%,籽粒产量提高14.2%;玉米籽粒产量构成的分析结果表明,不同处理玉米穗粒数差异显著(P<0.05),而百粒重却无显著差异。同时,HAU处理玉米对氮素和肥料氮的吸收量分别比U处理高0.989 g和0.072 g,提高了氮肥利用率4.8个百分点;各处理氮素和肥料氮在各器官的分配均表现为苞叶、穗轴<茎秆<叶片<籽粒,籽粒总氮和肥料氮的吸收量分别占整个植株地上部总吸收量的65.7%~74.2%和58.6%~60.5%;从氮素来源分析,各器官所吸收的肥料氮仅占该器官氮素总吸收量的13.3%~30.9%。另外,不同施氮处理对土壤中肥料氮的总残留量影响不显著,但HAU处理肥料氮在施肥层(0—15 cm)的残留量显著高于U处理(P<0.05)。HAU处理肥料氮的损失率为34.9%,低于U处理5.1个百分点。【结论】供试条件下,施用腐植酸尿素能够增加玉米干物质量和籽粒产量,促进玉米对肥料氮的吸收,减少肥料氮向下层土壤的淋溶,有利于土壤残留氮的进一步吸收利用。

[ Objectives ] In this study, effects ofhumic acid urea on maize dry biomass, grain yield, and the fate of fertilizer nitrogen were investigated. The result could provide a theoretical and practical basis for the prodection ofhumic acid fertilizer with better quality and higher efficiency. [ Methods ] Zhengdan 958 was selected as the test maize cultivar, and the tested humic acid urea was synthesized in the laboratory. The experiment was carried out by using technique of the 15^N-label and soil column culture. No nitrogen （CK）, common urea （U） and humic acid urea （HAU） were included as treatments, and all fertilizer was applied into 0-30 cm soil layer as base fertilizer. After the harvest, the maize shoots were collected and divided into five parts： leaf, stem, bract, cob and grain. Then, the dry biomass, nitrogen contents and 15^N abundance in all parts of maize shoots were determined, and ear traits were tested as well. The soil samples in different soil layers （0-15 cm, 15-30 cm, 30-50 cm, 50-70 cm, 70-90 cm） were collected after the harvest, and nitrogen contents and 15N abundance were determined subsequently. [ Results ] The dry biomass of shoots and individual organs, except bract, showed an ascending order as CK 〈 U 〈 HAU, no significant difference existed in the allocation ratio of dry matter in aboveground organs among the treatments. The aboveground dry biomass in HAU was 13.8% higher than that in U, and grain yield in HAU was 14.2% higher than that in U. The HAU enhanced grains per ear significantly （P 〈 0.05）, while increased the hundred kernels weight slightly. The uptake amounts of total N and fertilizer N in each column in HAU were 0.989 g and 0.072 g more than those in U, respectively. The fertilizer nitrogen use efficiency in HAU was enhanced by 4.80 percentage points compared with that in U. The allocation proportion of fertilizer N and total N in different organs showed an ascending order as： bract and cob 〈 stem 〈 leaf 〈 grain, and grain possessed 65.7%-74.2% of total N and 58.6%-60.5% of fertilizer N in shoots. The fertilizer N amounts accounted for 13.3%-30.9% of total N in individual organs. There was no significant difference in the total residue of fertilizer N between HAU and U. The residual amount of fertilizer N in 0-30 cm soil layer in HAU was higher than that in U, while the residual N in 30-90 cm showed an opposite trend. The loss rate of fertilizer N in HAU was 34.9%, which was lower than that in U by 5.1 percentage points. [ Conclusions ] Under the experimental condition, the application of humic acid urea could improve the maize aboveground biomass and grain yield, and regulate the fate of fertilizer nitrogen by enhancing fertilizer N uptake and reducing its leaching to soil deeper than 15 cm.