摘要
在日光温室条件下,研究了不同氮素供应水平对白萝卜(Raphanus sativus L.)氮素利用和土壤硝态氮累积动态,并对土壤-作物体系的氮素表观平衡进行了评估。结果表明,随氮肥用量的增加,白萝卜产量和干物质累积量均没有显著升高,但根块内富集的硝酸盐含量显著增加。增施氮肥对白萝卜维生素C(Vc),可溶性糖和可溶性蛋白含量没有显著影响;随施氮量增加白萝卜根块氮素吸收量显著增加,当季氮肥利用率降低;当氮肥用量低于推荐施氮量(有机肥+200kgurea-N·hm-2)时,整个白萝卜生长期,根层(0～60cm)土壤硝态氮均处于耗竭状态。当施氮量高于推荐施氮量时,根层硝态氮下降幅度减小,并在播种30d以后呈上升趋势;土壤-作物体系中播前无机氮(Nmin)和氮肥投入是主要输入项,输出项中以土壤无机氮残留和作物吸收为主。随施氮量的增加,氮素表观平衡值和土壤残留Nmin明显增加。系统氮素盈余量随施氮量的增加而增加。结合当地地力条件,在有机肥和磷钾肥配施的基础上,秋冬季白萝卜施氮量应控制在200kg·hm-2以内。
In intensive agricultural systems, excess application of nitrogen（ N ） fertilizer has been a common phenomenon. Although N is an essential nutrient to crops, traditional N management is difficult to maximize crop yields while reduce its losses to the environment. One major reason is that the transformation and fate of N fertilizer in agricultural soils as largely affected by crop N uptake is still not very clear under specific production systems. The objective of this study was to analyze the effect of different N rates on Raphanus sativus L. N utilization and dynamics of nitrate in soil layers, then evaluate N balance in the soil-vegetable system. The trial included six fertilization treatments as follows：No, no N fertilizer and manure; N1, chicken manure 6 326 kg ·hm^-2, N2, chicken manure 6 326 kg ·hm^-2＋100 kg urea-N ·hm^-2; N3, chicken manure 6 326 kg·hm^-2 ＋200 kg urea-N·hm^-2; N4, chicken manure 6 326 kg ＋300 kg urea-N ·hm^-2 ;N5, chicken manure 6 326 kg＋1 015 kg urea-N·hm^-2, respectively. All treatments replicated three times and arranged in a completely randomized design. The results showed that the yield and the dry matter of Raphanus sativus L. were not remarkably increased with the N fertilizer rate, but the concentration of nitrate in Raphanus sativus L. increased significantly with increased N level. There were no obvious treatment effects on vitamin C, soluble sugar and protein contents in Raphanus sativus L. by increased N fertilizer rate. The accumulation of N in Raphanus sativus L. root was increased and the efficiency of N was decreased with the N fertilizer rate. When the N fertilizer rate was lower than 200 kg urea-N·hm^-2, the nitrate of 0-60 cm soil layer was exhausting during the whole growth period. When the N fertilizer rate was higher than 200 kg urea-N ·hm^-2, the decreased extent of the nitrate of 0-60 cm soil layer was reduced and began increasing 30 days later; In the system of soil and Raphanus sativus L., N input mainly came from the application of N fertilizer and the residual inorganic nitrogen before planting. Residual inorganic nitrogen in soil and nitrogen absorbed by Raphanus sativus L. were main part in N output of system. The apparent N balance and the content of residual inorganic nitrogen in soil were significantly increased with the N fertilizer rate increased. N surplus was increased with the N fertilizer rate increased; According to the native conditions, on the base of mixing organic fertilizer and phosphor（P） fertilizer and potassium （K） fertilizer together, the N fertilizer rate should be controled below 200 kg·hm^-2 for Raphanus sativuz L. planted in autumn-winter.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2009年第7期1500-1507,共8页
Journal of Agro-Environment Science
基金
农田污染综合防控关键技术研究与示范(2006BAD17B09)
农田污染过程阻断关键技术研究(2006BAD17B03)
关键词
白萝卜
氮素利用
硝态氮
氮素平衡
Raphanus sativus L.
nitrogen recovery
nitrate
nitrogen balance
