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Nitrogen Utilization and Balance of Raphanus sativus L.Production System in Greenhouse
Author(s): ZHANG Guilong, REN Tianzhi, QIU Jianjun, LI Zhihong, LIU Hongbin, ZOU Guoyuan
Pages: 1500-
1507
Year: 2009
Issue:
7
Journal: Agro-Environmental Protection
Keyword: Raphanus sativus L.; nitrogen recovery; nitrate; nitrogen balance;
Abstract: 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:N0,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 phospho(rP)fertilizer and potassium(K)fertilizer together,the N fertilizer rate should be controled below 200 kg·hm-2 for Raphanus sativus L.planted in autumn-winter.
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