摘要
氮肥作基肥是我国农业生产中获得高产的一项重要措施 ,但作物对基肥氮的反应取决于土壤肥力条件及氮肥在土壤中的转化。本研究利用田间小区试验研究了尿素一次基施对高肥力草甸褐土中无机氮动态的影响。结果表明 ,冬小麦播前尿素作基肥施入土壤后首先影响表层土壤 (0～ 2 0 cm)无机氮的动态。施氮4 d后土壤铵态氮达到高峰 ,随后的 10 d内迅速下降至对照水平 ;而土壤硝态氮一直平稳升高于施肥后 14d左右达到最大值 ,以后直到冬灌前均无明显变化。说明本试验条件下土壤中尿素的水解和硝化作用在 2周内基本完成。小麦生长期间土壤剖面中铵态氮的含量一直保持较低水平 ,几乎不受施氮水平的影响。而土壤 0～10 0 cm剖面中硝态氮的含量随施氮量的增加而增加 ,且硝态氮向下层土壤移动的趋势也十分明显。但从各处理 10 0～ 2 0 0 cm土层中硝态氮含量没有明显差异的结果判断 ,冬前基施的尿素在冬小麦季淋溶出
Nitrogen applied as basal fertilizer is an important measure to obtain high yield in agricultural pratice. However, the crop's response to N fertilizer mainly depends on the soil fertility level and the transformation of fertilizer N in soils. In order to study the effect of basal application of urea on N transformation and dynamics of inorganic N, a field experiment with four N levels (0, 75, 112.5 and 150kg·hm -2 ) was carried out in a calcareous cinnamon soil in the campus of China Agricultural University, Beijing. The results showed that the applied urea was quickly hydrolyzed into NH 4 N within 4 days then converted to NO 3 N in the following 10 days. Except a small change in surface soil (0~20cm) just after urea application, NH 4 N in soil profile remained at a very low level during the whole growing period of winter wheat. On the contrary, the change of NO 3 N in soil profile was far more than that of NH 4 N. After a heavy irrigation before winter, NO 3 N in surface soil decreased while NO 3 N in deep soil (below 20cm) increased respectively, showing the movement of NO 3 N from surface soil into the lower layer. After harvest of winter wheat, the accumulation of NO 3 N in 0~100cm soil increased with the increase of N rate even more than 75kg·hm -2 . However, the amount of NO 3 N in 100~200cm soil among N treatments was not obvious different. These results showed that the movement of NO 3 N mainly concentrated on 0~100cm soil and the possibility of NO 3 N leaching to 100~200cm soil was too small during growing season of winter wheat when N rate was less than 150kg·hm -2 . In summary, large dose of N applied as basal fertilizer should be avoided in order to reduce N loss in high fertile soil.
出处
《中国农业大学学报》
CAS
CSCD
北大核心
2001年第5期63-68,共6页
Journal of China Agricultural University
基金
国家自然科学基金 (39870 4 79)
北京自然科学基金 (6980 0 0 1)
