Agricultural Engineering Research, Volume 6 (2000)

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/7126

Browse

Now showing 1 - 3 of 3

Determination of Soil-Related Trace Gas Fluxes during the Cultivation of Renewable Raw Materials
(2000) Hellebrand, Hans Jürgen; Scholz, Volkhard
The emission of climate- and environmentally relevant trace gases af- fects the environmental balance of renewable raw materials. Depending on the intensity and the kind of nitrogen fertilizing, additional nitrous oxide or ammonia is emitted, and methane degradation in the soil is in- fluenced. These trace gas fluxes are measured using the flux chamber method in connection with gas chromatography (GC) and Fourier- transform infrared spectroscopy (FT-IR). The GC technology provides the advantage of higher accuracy for some selected trace gases. The FT- IR measurements show that the release of ammonia caused by fertilizing with calcium ammonium nitrate is below the detection limit. The nitrous oxide emission factor measured at a loamy-sandy location is based on GC results. The average quantity of all fertilizer-induced N2 O-N emis- sions only amounts to approximately 0.2 % of the annual quantity of N- fertilizer applied. In addition, the GC measurements show that the de- gradation of atmospheric methane in the soil depends on the soil tem- perature. The mean annual value of methane degradation at the exam- ined location amounts to 0.7 kg CH4 ha-1 a -1.
Emissions Caused by Manure Composting
(2000) Hellebrand, Hans Jürgen; Kalk, Wolf-Dieter
The evaluation of the nitrogen balance of biological farming included the measurement of gaseous emissions during manure composting under practical conditions. The results show that ammonia- and methane emis- sions subside within three to four weeks. Nitrous oxide emissions exhi- bited significantly greater variability with regard to time and place. Ma- xima of nitrous oxide emission were observed mainly after ammonia and methane had decayed. The mean total flux per compost period amounted to 1,322 g m-2 of methane, 76.9 g m-2 of ammonia, and 19.8 g m-2 of ni- trous oxide. The relation of these average values to the mean flux of car- bon dioxide per composting period was 4.6 10-2 for CH4 , 2.7 10-3 for NH3 , and 6.9 10-4 for N 2 O. Both the total average gas flux and the mean ratio of total gas emissions can serve to quantify the impact on the envi- ronment. The average gaseous nitrogen losses measured during manure composting amounted to 6% of the initial nitrogen content. Carbon los- ses account for 35% of the initial carbon content.
Possibilities and Limits of the Use of Thermography for the Examination of Horticultural Products
(2000) Linke, Manfred; Beuche, Horst; Geyer, Martin; Hellebrand, Hans Jürgen
As a result of complicated heat- and substance exchange processes be- tween the produce and the environment after harvest, the temperature on the surface of fruit and vegetables is generally lower than the air tem- perature. Infrared thermography systems allow the distribution of these surface temperatures to be measured. Temperature differences are made visible in the form of colour differences and evaluated with methods of computer image analysis. The present contribution shows the possibili- ties and limits of the use of thermal imaging systems for examinations of quality changes of horticultural produce at the postharvest stage. In principle, such thermal imaging systems are able to measure produce properties connected with thermal processes (transpiration, respiration). They may lead to qualitatively new insights and thus make a contribution towards quality maintenance. When interpreting the results, the interrelation between the produce and its environment must always be taken into account.

Browse

Browsing Agricultural Engineering Research, Volume 6 (2000) by Person "Hellebrand, Hans Jürgen"