下层土壤容重对玉米植株养分吸收和分配的影响

 【目的】研究下层土壤容重对玉米植株N、P、K吸收和分配的影响。【方法】采用池栽试验，模拟大田不同土层容重实际存在状况,将池土分为3个层次, 各处理上层（0～20 cm）土壤容重保持一致，播前按照处理要求调整各个处理20～40 cm、40～60 cm两个土层的土壤容重。【结果】下层土壤容重对玉米N、P、K等营养元素的吸收有很大影响，其影响程度大小为K＞P＞N，这种影响在吐丝期表现尤为明显。N、P、K的积累量均随着下层土壤容重的增加而减小，而且处理间差异显著。N、P、K在各器官中的分配比例和转移率大小也受下层土壤容重的影响，特别是各个时期N、P、K在玉米生长中心中分配的比例随着土壤容重的增加而减少。不同层次土壤容重对N、P、K的吸收和分配均产生交互影响,且20～40 cm土层容重对N、P、K的吸收和分配的影响远大于40～60 cm土层。【结论】通过调整下层土壤容重,尤其是20～40 cm土层容重,可以促使玉米吸收更多的矿质营养，并使营养元素更多地向生长中心分配，促进玉米的生长和后期干物质的积累。

Influences of Soil Bulk Density in Deep Soil Layers on Absorption and Distribution of Nitrogen, Phosophrous and Potassium in Maize (Zea mays L.)

ObjectiveThe study was carried out to investigate the influences of soil bulk density in deep soil layers for absorption and distribution of nitrogen,phosophrous and potassium in maize.MethodThe pool cultivation were employed under field exposure. The pool soil was divided into three different soil layers: 0-20 cm (without any change in each treatment),20-40 cm and 40-60 cm with different soil bulk density (BD),which were adjusted before seeding. ResultThe main results showed that soil BD in deep soil layers had significant effects on absorption of N,P,K in maize,especially at the silking stage. Among nutrients,the order of the effects was K>P>N. Accumulation of N,P,K significantly differed among the five treatments with the order T224> T244>T226>T246>T266. Soil BD in deep soil layers also affected distributive proportion and transferring rate of N,P,K in the different organs,especially around the growth centre,of maize plant at different stages. The distributive proportion of N,P,K decreased with the increase of soil BD in deep soil layers. It showed the highest proportion in T224 and the lowest proportion in T266. Absorption and distribution of N,P,K in maize were interactively affected by soil BD of the two different deep soil layers.The effect of soil BD in 20-40 cm was more significant than that in 40-60 cm. Conclusion Adjustment of soil BD in the deep soil layers,especially the 20-40 cm layer,could enable maize plants to absorb more nutrients,to distribute more nutrients in organs around the growth center,and to improve accumulation of dry matter at the later growth stages.