红小豆氮肥施用时期的研究

Studies on little red bean of applying period and quantity of nitrogen

氮肥宜作红小豆追肥,最佳施肥期为分枝期～开花前,我市夏播麦茬红小豆可在7月20日～8月10日追施;当土壤耕层速效N含量中等(55PPM左右),亩施N1.25～2.5Kg为宜,亩施3.75Kg增产甚微,亩施5～6.25Kg减产,根据我市土壤普查资料,该结果对静海县及北辰区、武清、宝坻、蓟县等大部分红小豆产区具有指导意义。

Field experiments of nitrogn fertilizer applied to red bean showed that nitrogen fertilizer is suitable to use as top application,and the best application period is from branching stage to just before blooming. Red bean plants grown in the field of summer—sowing wheat stubble may be topduessed during the 20ty of July and the 10th of August in TianJin. On condition that the tillage layer of soil had medium amount of rapidly available N (55ppm approximately),1. 25～2. 5kg of N fertilizer applied per mu would be effective,while apply 3. 75kg per mu the effect is not significant on the yield. Oppositively ,ifapply5～6. 25kg N fertilizer, it would drop the yield. Referring the informations of general soil surrey inTianjin, the auther considers that the results of the experiments may be significantly directive to the most of red bean sowing areas,such as Jinghai,Wuqing,Baodi,and Jixan counties and the Noth suburb.