腐植酸尿素对玉米生长及肥料氮利用的影响

Effect of urea containing humic acid on maize growth and ^(15)N utilization

【目的】利用腐植酸对氮肥的增效作用,通过研究尿素中腐植酸添加量对玉米生长及肥料氮(15N)吸收、分配的影响,以期为腐植酸提高尿素肥效提供理论及实践依据。【方法】将腐植酸增效剂按1%、5%、10%、20%的比例分别添加到普通尿素中,利用熔融法制备四种腐植酸尿素试验产品(HAU1、HAU2、HAU3和HAU4),在土柱栽培试验中利用同位素15N示踪法,研究在等氮量(施氮量0.1 g/kg干土)投入情况下,尿素中腐植酸添加量对玉米生长,玉米肥料氮吸收、分配及肥料氮在不同土层分布的影响。【结果】与普通尿素处理(U)相比,1)四种腐植酸尿素处理均可显著提高玉米地上部生物量和籽粒产量,分别提高5.5%~13.8%和6.3%~17.3%,且随着腐植酸添加量的增加而提高。2)腐植酸尿素提高了玉米籽粒、茎、穗轴中的肥料氮含量,但差异不显著,同时降低了苞叶中的肥料氮含量;腐植酸尿素可显著提高玉米地上部和籽粒肥料氮的吸收量,分别增加11.6%~17.0%和16.8%~25.9%,但随着腐植酸添加量的增加,叶和苞叶中的肥料氮吸收量会有所降低;腐植酸尿素的肥料氮收获指数提高2.5~4.2个百分点。3)腐植酸尿素可显著提高15N肥料利用率和15N肥料土壤残留率,并降低15N肥料损失率,15N肥料利用率提高5.9~8.6个百分点,15N壤残留率提高1.4~2.5个百分点,损失率降低7.3~11.2个百分点。4)玉米收获后,土壤中的肥料氮主要残留在0—50cm土层,腐植酸尿素在0—90 cm土层中的肥料氮累积残留量比普通尿素高5.2%~10.1%。【结论】与普通尿素相比,在腐植酸增效剂添加比例为1%~20%的范围内,腐植酸对尿素均具有较好的增效作用,随着腐植酸添加量的增加,玉米籽粒产量逐渐增加;腐植酸还可促进玉米叶片和苞叶中的肥料氮向籽粒的转运,提高玉米肥料氮收获指数及籽粒肥料氮吸收量;同时还可提高尿素在土壤中的残留量,减少氮素淋溶损失。

【Objectives】In this study, effects of urea containing humic acid（HAU） on maize growth and fertilizer N uptake were investigated for providing support for rational use of humic acid in the improvement of urea efficiency.【Methods】Humic acid was added into urea in proportion of 1%, 5%, 10% and 20%（w/w） by melting method, and the four products were recoded as HAU1, HAU2, HAU3 and HAU4, respectively. A pot experiment was conducted using maize as test material and 15 N tracer technique. The maize growth, fertilizer N uptake and the fertilizer N distribution in soil profiles were investigated.【Results】1） Compared with the urea（U） treatment, the aboveground biomass and grain yields of the HAU treatments were significantly increased by5.5%–13.8% and 6.3%–17.3%, respectively, and the increases were enhanced with the increase of HA adding proportions. 2） The HAU treatments increased the fertilizer N contents in grains, stems and cobs, but decreased those in maize bracts. The total fertilizer N uptakes in aboveground parts were increased significantly by 11.6%to 17.0%, and those in grains were increased significantly by 16.8% to 25.9%, however, those in leaves and bracts were decreased. The nitrogen harvest indices of HAU were higher than that of the U treatment by percentage points of 2.5 to 4.2. 3） The HAU treatments significantly increased the N use efficiencies and N residual rates by percentage points of 5.9–8.6 and 1.4–2.5, respectively, while the N loss rates were decreased by percentage points of 7.3 to 11.2. 4） The total fertilizer N residues of the HAU treatments were 5.2%–10.1%higher than that of the U treatment in 0–90 cm soil layer, and the fertilizer N was mainly remaining in the 0–50cm soil layer.【Conclusions】Compared with the conventional urea, the addition of humic acids increases the effect of urea in maize yield increase, and the effect will be enhanced with the increased proportion of humic acid（ranging from 1% to 20%）. Humic acid containing urea can improve the nitrogen harvest index and promote the transport of fertilizer N from leaves and stems to grains, increase the fertilizer N residual rate in soil and decrease the leaching loss of fertilizer N.