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2004年12月25日,已是小寒后的第三天,南昌小雨转小雪,小雨过后,泥土湿漉漉的,一位绿化养护工人正给八一广场当年6月移栽的35厘米高的大叶黄杨撒施尿素追肥。尿素是一种适宜任何土壤的速效高氮氮肥,在土壤湿润时撒施作追肥虽无不当之处,但选择在严冬雨雪之日向刚成活的苗木追施,笔者认为不妥。苗木经移栽,根系受到很大伤害,虽定植了6个月,已安全越夏且初步适应了新环境,但根系仍不太健壮,不能及时全部地吸收追施的尿素。雨天追施,尿素易溶解淋失,降低氮的利用率,同时低温降低了根毛细胞膜对水分与水溶质的透性,同样会降低氮肥的有效利用率。尿素在土壤中受脲酶作用水解为(NH_4)_2CO_3),土壤中 NK_4~+(铵离
December 25, 2004, is the third day after the Osamu, Nanchang drizzle to light snow, light rain after the wet soil, a green conservation workers are being given August Bay Plaza transplanted in June of that year, 35 cm large leaves Poplar spraying urea dressing. Urea is a quick-acting, high-nitrogen-nitrogen fertilizer that is suitable for any soil. Although it is not unduly used when topdressing the soil when it is moist, it is not appropriate for me to choose the top seedling to survive in the winter and snowy days. Seedlings transplanted, the root system suffered great damage, although planted for 6 months, the summer has been safe and initially adapted to the new environment, but the root system is still not very robust, can not fully absorb the top-dressing urea. Rain topdressing, urea soluble leaching, reducing nitrogen utilization, while reducing the root hair cell membrane moisture and aqueous solute permeability, the same will reduce the effective utilization of nitrogen fertilizer. Urea in the soil hydrolyzed by urease to (NH_4) _2CO_3), soil NK_4 ~ + (ammonium