小麦追施氮肥的快速营养诊断技术研究

STUDIES ON THE TECHNICS OF NUTRIENT DIAGNOSIS FOR NITROGEN TOP DRESSING IN WINTER WHEAT

小麦分蘖期、拔节期可采用测定土壤和植株氮素营养的简易快速诊断技术,来确定各期的适宜施氮量。分蘖期以土壤有效氮含量作为施氮量指标,适宜施氮量为土壤有效氮指标(亩产450kg 左右,土壤有效氮指标为每亩11kg 纯氮)减去分蘖期0～40cm 土层内实测的有效氮含量之差值.拔节期以茎鞘基部硝态氮含量为施氮量的指标,其含量用二苯胺试剂比色法测定颜色等级。不同色级适宜的施氮量为每亩0～4kg 纯氮。

The paper deals with two methods of determining nitrogen fertilizer demand in thefield at two growing stages of winter wheat.Tillering stage:At the beginning or the tillering stage the quantity of mineral nitro-gen in the soil layer of 0 to 40 cm was determined.The optimum quantity of fertilizernitrogenat this stage was found 11kg N per mu minus kg N per mu present in the soillayer of 0 to 40cm.Jointing stage:In addition to the first nitrogen application winter wheat was sup-plied by the second top dressing.For this top dressing a rapid nitrate test was used.Thenitrogen quantity was determined by the nitrate concentration of the basal internode ofthe stem.The optimum nitrogen application ranges from 0 to 4 kg N per mu at this stage.