碳铵和尿素是我区施用的主要氮素化肥品种,它们的施用期影响肥效大小。本试验的目的就是从时间因素上来探讨这两种肥料作稻麦基肥的适宜施用期。试验于1982～83年在银川、永宁、青铜峡、灵武、连湖等市(县、场)的灌淤土上进行。共6个试验,各重复3次。土壤 pH8.3～8.6,CaCO_311～13％,<0.01毫米物理性粘粒50％左右,阳离子代换量10～14me/100克土,有机质1.3～1.5％,全氮0.08～1.0％,碱解氮80～120ppm,速效磷(p)8～15ppm。试验中配合基施足够的磷肥,追施适量的尿素,基施的氮素化肥用锹 Ammonium bicarbonate and urea are the main nitrogen fertilizers applied in our region, their application period affects the size of fertilizer. The purpose of this experiment is to explore the appropriate application period of these two kinds of fertilizers for rice-based wheat based on the time factor. The experiment was carried out on irrigated silt in Yinchuan, Yongning, Qingtongxia, Lingwu and Lianhu from 1982 to 1983. A total of six experiments, each repeated three times. Soil pH8.3 ~ 8.6, CaCO3 ~ 13%, <0.01 mm physical clay about 50%, cation exchange capacity 10 ~ 14me / 100 grams of soil, organic matter 1.3 ~ 1.5%, total nitrogen 0.08 ~ 1.0% Nitrogen 80 ~ 120ppm, available phosphorus (p) 8 ~ 15ppm. In the experiment with enough phosphate base facilities, topdressing the amount of urea, basal nitrogen fertilizer spade