【作者】 王贺；

【导师】 白由路；

【作者基本信息】 中国农业科学院 ， 植物营养学， 2012， 博士

【摘要】 选择合理的施肥方法是提高夏玉米产量、减少肥料资源浪费的重要措施，施肥方法影响着作物的根系形态、养分吸收、干物质累积、产量形成及肥料养分在土壤中的分布特征。目前，关于常规肥料施用方法的研究相对较多，而随着缓/控释肥料的快速发展，其养分释放特征与常规肥料有明显区别，传统的施肥方法可能不适合缓/控释肥料的实际应用，对于缓/控释肥料施用方法的研究需求也更加迫切。本文根据实际生产需要，研究不同类型肥料施用方法对夏玉米养分吸收、利用的影响，探讨不同施肥方法对夏玉米养分吸收、利用的作用机理。试验选择的施肥位置主要包括种子侧下位5cm、侧下位10cm、正下位5cm、正下位10cm，施肥方式选用条状施用和点状施用。采用盆栽试验、根箱试验和大田试验三种手段相结合开展研究：通过盆栽试验研究了氮、磷、钾养分的不同施用位置对夏玉米生长初期根系生长、养分吸收及干物质累积的影响，通过根箱试验研究了控释氮肥不同施用位置对玉米根系分布及氮素养分在土壤中扩散特点的影响，通过大田试验评价了不同施肥方法的肥料综合效应，主要结论如下：（1）普通尿素施用位置对玉米种子萌发及初期生长影响较大。侧下位5cm点状施用和正下位5cm点状施用处理对玉米苗期根系生长产生明显抑制作用。侧下位10cm点状施用或侧下位10cm条状施用处理玉米干物质累积量较大，侧下位10cm条状施用处理玉米干物质累积量、养分吸收量及根系长度高于其他处理。普通尿素大量集中施用条件下，以侧方条状（或分散状）施肥方式为佳，不宜采用种子下方施用。（2）包膜尿素施用位置对玉米种子萌发无明显抑制作用，对玉米初期生长的影响程度与其养分释放特点及其用量有关。试验肥料较高用量条件下，玉米出苗后10d，不同施肥位置对玉米干物质累积、养分吸收无明显影响；玉米出苗后30d，正下位点状施肥处理植株养分吸收量及干物质累积量低于侧下位点状（条状）施肥处理。包膜尿素侧下位条状施用处理根系长度、养分吸收量及干物质累积量高于其他处理。（3）磷肥施用位置对玉米生长初期的根系长度、养分吸收及干物质累积量有明显影响，磷肥点状集中施用促使玉米根系在磷肥施用位置上产生明显根团。试验土壤上，磷肥侧下位5cm点状施用和正下位5cm点状施用处理干物质累积量、养分吸收量及根系长度明显高于磷肥侧下位10cm点状施用处理和磷肥正下位10cm点状施用处理。可见，磷肥施入在种子较近距离，玉米能够较早吸收磷素养分，促进玉米根系生长，增加玉米对磷素养分的吸收。（4）钾肥施用位置对玉米生长初期植株干物质累积量及养分吸收量影响较小，对植株含钾量和根系干重有一定影响，钾肥侧下位和正下位5cm点状施用处理植物含钾量和根系干重低于10cm点状施用处理。试验中观察发现，玉米根系沿着钾肥施用点的外围生长，对钾素浓度较高区域有趋避性。（5）控释氮肥施用位置对玉米根系形态、干物质累积量、养分吸收及氮素养分在土壤中运移有明显影响。玉米生长45d时，正下方10cm施用控释氮肥处理地上部干物质累积量和植株吸氮量明显高于侧下方10cm施用控释氮肥处理，玉米生长100d时，二者无明显差异。夏玉米根系主要分布在0~40cm土层内，其中0~20cm最多，随着深度增加，根系逐渐减少。玉米根系具有趋肥性，侧下方施肥处理施肥一侧的根系长度明显大于不施肥一侧的根系长度；与下方施肥处理相比，侧方施肥处理施肥一侧的根系长度大于下方施肥处理同侧的根系长度；而在未施肥一侧，侧方施肥处理施肥一侧的根系长度明显小于下方施肥处理同侧的根系长度。在同一土层，侧方施肥处理的根系总长度都低于下方施肥处理。试验土壤上，控释氮肥氮素养分横向扩散半径为6~10cm，且有明显的下移特征。侧方施肥处理氮素养分主要分布在玉米植株的单侧，而下方施肥处理氮素养分扩散范围基本在玉米根系较为密集的植株正下方。（6）大田试验研究表明，条状施肥条件下，普通尿素分次施用比一次施用能够提高9%玉米产量，缓释肥料一次施用与常规肥料分次施用产量无明显差异；不同位置点状施用缓释肥料，玉米产量不同，侧下方5cm点状施肥处理和正下方10cm点状施肥处理产量高于其他处理。侧下方5cm点状施用缓释肥料处理，玉米成熟期氮、磷、钾累积量最高，分别为217.8kg/hm2、29.3kg/hm2、191.8kg/hm~2。施肥方法明显影响着肥料养分的利用效率、经济效益和环境效益。普通尿素一次施用处理氮、磷、钾的当季回收率最低，分别为9.5%、11.2%、22.6%；侧下方5cm点状施用80%缓释肥料处理氮、磷、钾当季利用率最高，分别为35.8%、19.3%、54.8%。不计劳力成本条件下，普通尿素分次施用处理肥料经济收益最高，但与缓释肥料侧下方5cm点位施用和正下方10cm点位施用处理差别较小。施用缓释肥料能够减少硝态氮向下淋洗，保持氮素养分在较浅土层，利于下季作物吸收利用。与常规肥料相比，缓释肥料可施入到离种子较近位置。种子正下方施用缓释肥料能够促使养分扩散区域与玉米根系吸收区域耦合，减少肥料资源浪费，促进玉米对养分的吸收和利用，提高夏玉米产量。更多还原

【Abstract】 Reasonable fertilizer application method is an important technical measure to improve summermaize yield and reduce the waste of fertilizer resource. The fertilizer application method affects on theroot morphology, nutrient uptake, dry matter accumulation and yield of crop; meanwhile it affects on thedistribution characteristics of fertilizer nutrients in the soil. At present, these studies on applicationmethods of conventional fertilizer are more concerned, and some methods had relatively matureapplication in summer maize production. However, with the rapid development of slow/controlledrelease fertilizer, the application methods of conventional fertilizer may not be suitable for theslow/controlled release fertilizer because the slow/controlled release fertilizer has different nutrientrelease characteristics comparing with conventional fertilizers. Hence the study on application methodsof slow/controlled release fertilizer is more and more urgent.The effects on summer maize nutrient uptake and utilization of different application methods werestudied and discussed in this paper. The fertilization placements included the seed side5cm, seed side10cm, seed undersurface5cm, and seed undersurface10cm and the fertilization methods includedpoint fertilization and band fertilization.The effects of nutrient application placements on root growth,nutrient uptake and dry matter accumulation in early growth stage of summer maize were studied by potexperiments, the effects of different fertilizer application placements on root distribution and nutrientdiffusion range in the soil were researched by a root box experiment, the comprehensive effects onmaize yield,economic and environmental benefits of different fertilizer application methods wereevaluated by a field experiment. The main conclusions were as follows:(1) The effects of urea application placements on seed germination and growth of maize seedlingstage were significant. Relatively short distance application would significantly inhibit the maizeseedling growth. In all the treatments, the point application urea of the seed side10cm and the bandapplication urea of the seed side10cm were better than other treatments. The dry matter accumulation,nutrient uptake amount and root length of the band application urea were the largest in all the treatments.It should be paid attention to the distance and direction between urea and seed when urea was centralizedapplication, and did not apply urea below the seed, therefor, band application methods were relativelyreasonable and recommended.(2) The effects of coated urea application placements on the growth of maize seedling stage werenot as significant as normal urea, and the effect way and degree were closely related with nutrientreleased characteristics and application rate of the coated urea. Under the higher fertilizer dosageconditions, the point fertilization below seed may still inhibit the maize root growth. After10days ofgrowth, there were no significant differences on the seedling growth for different treatments due to thenutrient of coated urea released slowly; however, the dry matter accumulation, nutrient uptake amountand root length of the band application urea were the largest in all the treatments after30days ofseedling.(3) The application placements of phosphorus fertilizer significantly affected on the dry matter accumulation, nutrient uptake amount and root length, the point application of phosphorus fertilizercould induce maize root to form the obvious root ball in the phosphate fertilization position. Thedistance between the phosphate fertilizer and seeds was closer，the longer the root length，the greater theamount of dry matter accumulation and the more nutrient uptake. The application orientation ofphosphorus fertilizer, seed side and seed undersurface, had not significant influence on maize growth.(4) Different application methods of potassium fertilizer had little effects on the dry matteraccumulation in maize seedling stage, whereas it had effect on the potassium content of plant and rootdry weight. It was found that the maize root grew along the periphery of the fertilization point, and rootgave a wide berth for high concentrations of potassium fertilizer area. Therefore, it is not as close aspossible for point application of potassium fertilizer.(5) Under root box conditions, the effects of the application placements of controlled releasenitrogen fertilizer on maize root morphology, dry matter accumulation, nutrient uptake and transport ofnitrogen nutrients in the soil were significant.After45days of sowing, aboveground dry matteraccumulation amount and plant N uptake of the treatment which fertilizer placement is at seedundersurface10cm (BF)was significantly higher than the treatment which fertilizer placement is at seedside10cm(SF),but it was no significant difference when maize was mature.The results show thatnitrogen nutrient horizontal diffusion radius was6-10cm when the nutrient release ratio of thecontrolled release nitrogen fertilizer was highest, and the nitrogen nutrients moved down significantly.Summer maize roots were mainly distributed in the0-40cm soil layer, the root density decreasedgradually with the soil depth increasing. Maize root growth had evident fertiliertaxis. The root length inthe fertilization side of the SF treatment was obviously longer than the no fertilizer side, and also higherthan the root length on the same fertilization side of the BF treatment. In no fertilizer side, the rootlength of the BF treatment was significantly higher than the root length of the SF treatment. In the samesoil layer, the total length roots of the SF treatments were slightly lower than that of the BFtreatments.To the BF treatment, nutrition diffusion zone completely centralized in the dense regions ofroot system, which could provide sufficient nutrients to the maize growth.(6) The experiments results show, under the band fertilization conditions, urea application at twicecould increase maize yield compared with once application, and the yield of the slow release fertilizerhad no significant difference with that of urea application at twice.Under the conditions that slow releasefertilizer were point application,the yield of fertilizer use was reduced by20%was slightly lower thanthat of fertilizer use were100%,whereas the difference was not significant.Fertilizer applicationmethods influenced the nutrients uptake in different maize growth periods. The application effect ofpoint fertilization methods with10cm below the seed and with5cm beside the seed was better thanother fertilization methods, the maximum accumulation amount of nitrogen, phosphorus, potassium was217.8kg/hm2,29.3kg/hm2,191.8kg/hm2, respectively.The fertilizer application methods hadsignificant effect on the use efficiency of fertilizers, economic and environmental benefits. The recoveryrates of nitrogen, phosphorus, potassium fertilizer of once application urea treatment were lowest, whichwere9.5%,11.2%and22.6%, respectively; however, the highest recovery rate of nitrogen, phosphorus, potassium fertilizer were the treatment of fertilizer was point application at5cm beside seed (80%fertilizers use), which were35.8%,19.3%and54.8%, respectively. Under excluding the cost of laborconditions, urea application at twice had the highest economic profits, whereas there were no significantdifferences compared with the treatment of fertilizer was point application at5cm beside the seed. Theapplication of slow release fertilizer could reduce nitrate leaching, maintain nitrogen nutrients in theupper soil, and be conducive to the absorption and utilization of the next season crop.Overall, compared with conventional fertilizer, the slow/controlled release fertilizer should apply tothe closer placement of the seed, which could promote crop to uptake and use the fertilizer nutrients, andimprove the yield of summer maize.The application of slow/controlled release fertilizer below seedcould promote the nutrient diffusion region coupled the region whose root absorption capacity was larger,reduce the waste of fertilizers, and improve the yield.更多还原