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尿素是含氮最高的生理中性肥料,长期施用,对土壤无副作用。但作追肥时,应严格掌握以下几点: 一、追肥深施:尿素与碳酸氢铵相比,虽然物理性状好,化学性质稳定,但施入农田后,在脲酶的作用下,转化为碳酸铵和碳酸氢铵,其性质与碳酸氢铵一样,具有较强的挥发性,从而使氮素损失,肥效降低。为此,无论是旱地或是水田,尿素作追肥都应深施,以提高氮素利用率。水稻田深施,不仅可防止氮素的硝化淋失,而且能防止反硝化作用造成脱氮损失。二、提前早施:因为尿素施入土壤中,不能直接被作物吸收利用,必须转化为铵态氮后,作物才能利用,尿素转化除与土质、有机质含量有关外,与气温高低密切相关。在气温高的条件
Urea is the highest nitrogen-containing physiologically neutral fertilizer, long-term application, no side effects on the soil. But for top dressing, the following points should be strictly controlled: First, the top dressing fertilizer: urea and ammonium bicarbonate, although the physical properties are good, chemical stability, but after the application of farmland, under the action of urease into carbonate Ammonium and ammonium bicarbonate, its nature and ammonium bicarbonate, with strong volatility, so that nitrogen loss, fertilizer efficiency. To this end, whether it is dry land or paddy fields, urea should be applied as top dressing to improve nitrogen utilization. Deep paddy fields, not only to prevent nitrification leaching of nitrogen, but also to prevent denitrification caused by loss of denitrification. Second, early implementation: Because urea applied to the soil, can not be directly absorbed by crops, must be converted to ammonium nitrogen after the crop can use, in addition to urea conversion and soil, organic matter content, and the temperature is closely related. In high temperature conditions