基于磷肥施用深度的夏玉米根层调控提高土壤氮素吸收利用

The root-layer regulation based on the depth of phosphate fertilizer application of summer maize improves soil nitrogen absorption and utilization

良好的根系构型能够促进作物高效获取土壤养分。基于磷肥施用深度的根层调控技术可以优化夏玉米根系的时空分布并促进其与土壤水分、养分供应的空间匹配性,为通过玉米根系挖潜实现节肥增效提供理论与技术支撑。本试验以不施磷肥处理为对照(CK),设置距离地表-5 cm(P5)、-10 cm(P10)、-15 cm(P15)和-20 cm(P20)深度施用磷肥处理,分析各处理对夏玉米根系分布、植株生长及产量形成、氮素吸收、积累与转运的影响。结果表明,磷肥适当深施显著促进夏玉米根系生长,根干重、根长密度、根系表面积和根体积均显著增加,整体表现为P15>P10>P20>P5>CK。随着磷肥施用深度的增加,深层玉米根系显著增加。P15和P20处理根干重所占比重,在20~40 cm土层分别为12.3%和12.1%;在40~60 cm土层分别为6.7%和6.9%。根系分布深度的增加促进了对土壤氮素的吸收,深施磷肥处理各土层中尤其是20 cm以下土层土壤氮素含量显著降低。根系分布的优化同时促进了植株氮素积累与转运,P15处理较P5处理氮素吸收效率、氮积累量、转运量及氮肥偏生产力2年平均分别提高14.5 kg kg^-1、19.2%、48.9%和6.4 kg kg^-1,籽粒产量2年平均增产16.4%。在本试验条件下,磷肥集中施用在−15 cm处理,能显著促进夏玉米深层土壤根系的生长,扩大根系养分利用空间,增加根系对深层土壤氮素的吸收,促进植株氮素积累及转运,提高其生产力,最终提高产量。

Favorable root phenotypes can promote crops to obtain soil nutrients efficiently.The root-layer regulation technology based on the depth of phosphate fertilizer application can optimize the spatial and temporal distribution of summer maize root system and promote its spatial matching with soil water and nutrients to supply,providing a theoretical and technical support for realizing fertilizer saving and efficiency improvement by tapping potential of maize root system.In the present study,there were five treatments including CK(no P applied),P5(phosphorus placement depth of 5 cm),P10(phosphorus placement depth of 10 cm),P15(phosphorus placement depth of 15 cm),and P20(phosphorus placement depth of 20 cm).The effect of phosphorus application depth on root distribution,plant growth and yield formation,as well as nitrogen uptake,accumulation and transport in summer maize was analyzed.The suitable application depths of phosphate fertilizer promoted the growth of summer maize roots and increased root dry weight,root length density,root surface area and root volume significantly totally showing a trend of P15>P10>P20>P5>CK.With the increase of phosphate fertilizer application depth,the deep corn roots increased significantly.The proportion of root dry weight in P15 and P20 treatments was 12.3% and 12.1% in the 20–40 cm soil layer,and 6.7% and 6.9% in the 40–60 cm soil layer,respectively.The increase of root distribution depth promoted the absorption of nitrogen in the soil,and the nitrogen content in each soil layer,especially below 20 cm,was reduced significantly by the deep application of phosphate fertilizer.The optimization of root distribution promoted the accumulation and transportation of nitrogen in plants.Compared with P5 treatment,the averaged nitrogen fertilizer absorption efficiency,accumulation amount,accumulation rate,partial factor productivity and the grain yield in two years of P15 treatment increased by 14.5 kg kg^-1,19.2%,48.9%,6.4 kg kg^-1,and 16.4% respectively,showing that under the conditions of the present study,concentrated application of phosphate fertilizer in−15 cm treatment can significantly promote the growth of deep soil roots,expand the space of nutrient utilization for root system,increase the absorption of nitrogen in deep soil,promote the accumulation and transportation of plant nitrogen,improve the productivity and ultimately yield in summer maize.