夏秋反季节无公害甘蓝氮肥适宜用量研究

Rational N fertilizer application for pollution-free cabbage cultivation in the off-season

甘蓝氮肥适宜用量的田间试验结果表明:氮肥适宜用量为纯氮300～400kg/hm2。其中,基肥氮用量占40%,与磷、有机肥混合干施;追肥氮用量占60%,采用分次对水浇施,每次用量不超过50kgN/hm2。采用此施肥量和方法,可获得较高的产量(约55t/hm2)和较高的产投比(≥3 14)。硝酸盐含量和亚硝酸盐含量低于国家标准(GB/1840 6-2001)规定叶菜类硝酸盐和亚硝酸盐含量的限量标准。

The trials of suitable amount of N-fertilizer application for pollution-free cabbage cultivation was carried out in summer of 2003. The results showed that the suitable amount of N-fertilizer applied for no pollution cabbage cultivation was 300-400 kg/hm^2 (net nitrogen),which consisted of base manure (accounting for 40 % in all) mixed with phosphate fertilizer and organic manure, and additional fertilizer (accounting for 60 % in all),which was divided into four times and adulterated with water for top dressing. But it should not be exceeded 50 kg /hm^2 for each time.Based on this manure amount and method, the higher yield (about 55 t/hm^2) and higher output/input (above 3.14) ratio can be obtained in cabbage cultivation. The contents of nitrate and nitrite in cabbage leaves were below the permitted level of national standard (GB18406.1-2001).