土壤深松下磷肥施用深度对夏玉米根系分布及磷素吸收利用效率的影响

采用大田试验与土柱试验相结合的方式,设置距离地表-5 cm (P5)、-10 cm (P10)、-15 cm (P15)和-20 cm(P20)施用磷肥处理,以不施磷肥为对照(CK),研究磷肥施用深度对夏玉米根系分布、干物质积累与产量形成及磷肥吸收和利用效率的影响。结果表明,磷肥施用深度显著影响夏玉米根系干重及根长,表现为P15P10P20P5CK。与常规磷肥施用深度(P5)处理相比,P15处理玉米籽粒产量两年平均提高23.1%,根干重及总根长两年平均提高13.1%、22.9%; P15、P20处理均增加了-20 cm以下土层的根干重比例及根长比例,土柱试验分别达到35.4%和36.4%、58.7%和59.3%,大田试验根干重两年均达到19.0%,根长比重分别达到39.8%和39.9%。根系分布的优化促进了植株磷素积累与转运, P10、P15、P20处理较P5处理磷积累量2年平均提高10.6%、25.2%和14.7%,磷转运量平均提高46.9%、76.6%和57.6%,籽粒产量相应增加12.9%、23.1%和10.6%。P15比P5处理的磷肥偏生产力、农学利用效率和表观利用效率两年平均值分别提高19.1 kg kg~(–1)、19.1 kg kg~(–1)和25.2%。磷肥深施能够增加深层土壤根系的分布比例,提高植株对磷肥的吸收、利用效率,显著提高夏玉米产量,在本试验条件下以磷肥集中施用在-15 cm处效果最好。

Effects of phosphorus fertilizer application depths on root distribution and phosphorus uptake and utilization efficiencies of summer maize under subsoiling tillage

Phosphorus fertilizer application depths are extremely important for increasing phosphorus uptake and utilization efficiencies. In the present study, root distribution, biomass, grain yield, phosphorus uptake and utilization efficiencies were determined in field experiment and soil column experiment, with five treatments including CK (no P applied), P5 (phosphorus application depth was 5 cm), P10 (phosphorus application depth was 10 cm), P15 (phosphorus application depth was 15 cm), and P20 (phosphorus application depth was 20 cm). Phosphorus fertilizer application depths significantly affected root dry weight and root length of summer maize with a trend of P15>P10>P20>P5>CK. Compared with P5 treatment, averaged grain yield of P15 treatment increased by 23.1% in two years, averaged root dry weight and total root length increased by 13.1% and 22.9% in two years. Both P15 and P20 treatments increased the proportion of root dry weight and root length in the soil layer below -20 cm. The proportion of root dry weight of P15 and P20 treatments reached 35.4% and 36.4%, and the proportion of root length reached 58.7% and 59.3% in soil column experiments; the proportion of root dry weight both reached 19.0% and the proportion of root length reached 39.8% and 39.9% in field experiment, respectively. The optimization of root distribution promoted the accumulation and transport of phosphorus in plants. Compared with P5 treatment, P10, P15, and P20 treatments increased the averaged phosphorus accumulation in two years by 10.6%, 25.2%, and 14.7%, the average phosphorus transport amount in two years by 46.9%, 76.6%, and 57.6%, and the grain yield by 12.9%, 23.1%, and 10.6%, respectively. Compared with P5 treatment, P15 treatment increased the averaged P partial factor productivity, P agronomic efficiency and P apparent utilization efficiency by 19.1 kg kg ^-1, 19.1 kg kg ^-1, and 25.2% in two years, respectively. In summary, deep fertilization of phosphorus could increase the distribution of root in deep soil layers, improve the absorption and utilization efficiencies of phosphorus in plants, and significantly improve the grain yield of summer maize. Under the condition of this study, the suitable P fertilizer application depth was 15 cm from the soil surface.