N2O emissions from a vegetable field as affected by ammonium depot fertilization and by the use of a nitrification inhibitor
- Publikations-Art
- Vortrag
- Autoren
- Reiner Ruser, Helena Pfab, Iris Palmer, Julia Spengler, Sabine Fiedler, and Torsten Müller
- Erscheinungsjahr
- 2010
- Tagungsname
- JKI-Symposium Fertilizer Injection
- Tagungsort
- Braunschweig
- Tagungsdatum
- 10.02.2010
<p></p> <p class="MsoNormal" style="text-align: justify;"><span>In order to test the effect of different fertilization strategies on the emission of the climate relevant trace gas N<sub>2</sub>O, we determined annual N<sub>2</sub>O fluxes from a vegetable cultivated field at an experimental site of the Universität Hohenheim. Annual flux measurements are a prerequisite for the reliable evaluation of the atmospheric impact of agricultural management practices because up to 70% of the annual N<sub>2</sub>O emission might occur outside the cropping season. </span></p> <p class="MsoNormal" style="text-align: justify;"><span> </span></p> <p class="MsoNormal" style="text-align: justify;"><span>Soil type of our experimental site near Stuttgart was a Luvisol derived from loess. The soil was planted with lettuce followed by cauliflower. The following treatments were tested: broadcast N application of solid ammonium nitrate sulfate (ANS), broadcast application of ANS with the nitrification inhibitor 2,4-DMPP (ANS+NI), and a depot-fertilization with solid ANS to cauliflower. The depot fertilization can be characterized as a Pseudo-CULTAN treatment. The depot was placed banded in 10 cm depth below the plant row. N-demand was calculated according to the KNS-Sollwert and accounted for 435 kg N ha<sup>-1</sup> (both crops) in each treatment. </span></p> <p class="MsoNormal" style="text-align: justify;"><span> </span></p> <p class="MsoNormal" style="text-align: justify;"><span>There was no effect of these three treatments on the yield of lettuce or cauliflower. The annual N<sub>2</sub>O emission in the treatment with broadcast ANS application was 8.8 kg N</span><sub><span style="font-size: 10pt;">2</span></sub><span>O-N ha</span><sup><span style="font-size: 10pt; position: relative; top: -2pt;">-1</span></sup><span><span> </span>yr</span><sup><span style="font-size: 10pt; position: relative; top: -2pt;">-1</span></sup><span>. The N<sub>2</sub>O flux rates were positively correlated with increasing soil moisture and nitrate contents of the top soil indicating, that denitrification was the main source for the N<sub>2</sub>O released. The emission from the soil with nitrification inhibitor was 4.9 kg N<sub>2</sub>O-N ha<sup>-1</sup> yr<sup>-1</sup>. As compared to the ANS treatment this corresponded to a reduction of 44%. The annual N<sub>2</sub>O emission from the soil with depot fertilization was not statistically different from the one with broadcast ANS application. It was 10.5 kg N<sub>2</sub>O-N ha<sup>-1</sup> yr<sup>1</sup>. The high emission from the depot treatment and the nitrification inhibitory effect in the depot suggest, that the high nitrate concentrations in the surrounding of the depot favored N<sub>2</sub>O release from denitrification.</span></p>