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Influence of nitrogen concentration and form in the nutrient solution N 2 0 and N 2 emissions from a soilless culture system
Author(s) -
Daum Diemo,
Schenk Manfred K.
Publication year - 1996
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.1996.3581590606
Subject(s) - denitrification , nitrogen , nitrate , nutrient , hydroponics , ammonium , nitrous oxide , chemistry , agronomy , greenhouse gas , environmental chemistry , zoology , biology , ecology , organic chemistry
The influence of nitrogen concentration and form in the nutrient solution on the N 2 O and N 2 emissions from a closed rockwool system with cucumber crops was investigated. At optimum, nitrate‐accented nitrogen supply of plants (120 mg N l −1 ) on average 0.59 kg N per hectare greenhouse area and day was released. Comparable emission rates occurred with moderate sub‐ and supraoptimum nitrogen fertilization. Thus, in this range the N supply was non‐limiting for the gaseous nitrogen losses. Only in the case of severe suboptimum N supply (40 mg N l −1 ) the N 2 O N 2 emissions were clearly lower, probably as a result of diminished plant growth and therefore reduced root respiration and exudation of organic carbon sources for microorganisms. The proportion of nitrous oxide in the gaseous nitrogen losses increased on average from 5 to 13% with increasing N supply, possibly because of an impaired N 2 O reduction in denitrification due to high nitrate concentrations. Short‐term shifting with optimum nitrogen supply from nitrate‐ accented composition to pure nitrate did not affect the gaseous nitrogen emissions, whereas an exclusive ammonium supply resulted in a considerable decrease. The results indicated that the N 2 O emission and the total nitrogen losses from the soilless culture system were predominantly caused by denitrification.