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河套灌区(包括后套、三湖河及土默川灌区)应用化肥历史很短,目前春小麦地区推广应用尿素,一般施肥量已达到每亩10～12斤氮素,用氮肥作追肥施用,每斤氮素仅增产小麦不到10斤,氮素利用率在20～30％,群众反映增产不增收,成为生产上一个重要问题。本区氮肥肥效不高的主要原因是追肥时期太晚,因春小麦需要氮素营养的关键时期是分蘖期,而当地大部分麦田受河水灌溉水期的限制不能在分蘖期前及时追肥灌水。过去春麦不提倡氮肥尤其是尿素作种肥,因为它影响出苗比较严重,但本区地处高原,气候寒冷,春小麦生育期短,播期气温又低,小麦生育期特别是前期降雨量少,灌溉又不及时,因此有发展种肥的需要与可能。1964年开始,我们在土默川灌区农村基点试验推广小麦尿素种肥。到70年代中期,在本灌区及其附近地区已发展到约300万亩,每亩种肥用量为5～8斤尿素,每斤氮素比拔节期追肥多增产约
Hetao Irrigation District (including after the set, the three lakes and Tumochuan Irrigation) application of chemical fertilizer is very short history, the current promotion of the use of urea in spring wheat area, the general fertilizer has reached 10 to 12 kg per mu nitrogen, with nitrogen fertilizer for top dressing, N kg of wheat yield only less than 10 pounds of wheat, nitrogen utilization rate of 20 to 30%, the masses reflect the increase does not increase income, become an important issue on the production. The main reason for the low nitrogen fertilizer efficiency in this area is that the top dressing period is too late. The key period for spring wheat to need nitrogen nutrition is the tillering stage. However, most of the wheat fields in the region are limited by the irrigation water period and can not be timely topdolitized and irrigated before the tillering stage. In the past, spring wheat did not promote nitrogen fertilizer, especially urea as seed fertilizer, because it affected the emergence of more serious, but the area is located in the plateau, cold climate, short spring wheat growth period, sowing temperature is low, wheat growth period, especially the early rainfall less, Irrigation is not timely, so there is a need and possibility of developing seed fertilizers. Since 1964, we have been experimenting with wheat urea fertilizers in rural areas in the Tumochuan irrigation area. By the mid-1970s, about 3 million mu had been developed in this irrigation area and its vicinity, with 5 to 8 kg of urea per acre. Nitrogen per kilogram increased more than that of top dressing at the jointing stage